Тюнинг sportster 883 -> 1200

Перевод Александра Скифа. Chernyshov.as@gmail.com

Многие владельцы 883ccm Sportster’ов желают увеличить объем двигателей до 1200ccm. Это наиболее эффективный способ увеличить крутящий момент и количество л.с. Стоковый 883ccm Evolution выдает около 42 л.с. на заднем колесе. Подбором правильной комбинации апгрейдов возможно поднять мощность до 100 лошадок. Эта статья призвана внести рациональное зерно в выбор пути апгрейда вашего 883 Sporster’а. Она не претендует на всеобъемлимость и постоянно редактируется.
Почему я ее написал? Как и многие из вас, я имею некоторые знания о двигателях и Харлеях. Однако, я быстро понял, что картину вещей в целом я не представляю. По этой причине я начал изучать сайты типа Sportster.org для получения ценных технических знаний. Технари, которые обитают на этих сайтах, имеют многолетний опыт и могут дать быстрый совет. Ты сделаешь правильно, если послушаешь их. Вся информация содержащаяся здесь, взята с рассылки сайта Sportster.org.
Вернемся к вопросу, почему я написал эту статью. Как многие из вас, я не знал с чего начать при увеличении объема двигателя моего байка. Оказалось так много переменных, что такой новичок как я, мог быстро потеряться в терминологии … зазоры, завихрения, углы опережения, градусы. Я стал собирать интересные сообщения, относящиеся к апгрейду, в своем почтовом ящике. В конце я собрал все эти посты в один файл, который и стал основой этого ЧАВО.
Я взял на себя ответственность определить три различных варианта возможного апгрейда. Эти направления четко не определены и просто показывают возможные пути решения проблемы. Однако, как будет показано ниже, описанные комбинации реально используются людьми для апгрейда своих Харли. Так же в статью был включен раздел наиболее часто задаваемых вопросов касательно апгрейда и ответов на них.
Это обзорная материал, за прямыми инструкциями по увеличению объема с 883 до 1200 ccm советую обратиться к техническим архивам сайта  http://www.sportster.org/. Эта статья подразумевает, что у вас уже установлены фильтр нулевого сопротивления, тюнинговый выхлоп и доведен до ума стоковый Кейхин. Если это не сделано, то советую прочитать следующие статьи  http://www.sportster.org/tech/basic-perf/stage-list.txt http://www.sportster.org/tech/basic-perf/harley-tax.txt

Переходим к интересному.

Варианты апгрейда:

ВАРИАНТ №1: ДЕШЕВО И СЕРДИТО
Итоговая мощность: 62 л.с (прирост в 20 лошадок, по сравнению со стоком)
Итоговый момент: 72 Н•м (прирост в 20 Н•м, по сравнению со стоком)
Цилиндры: можно расточить существующие стоковые или купить от 1200 кубовой версии.
Поршни: Wiseco (http://www.wiseco.com/) #1655 (степень сжатия 9,5)
Кольца: производства компании Хастинг (http://www.hastingsmfg.com/)
Головки цилиндров: стоковые
Распредвалы: стоковые
Зажигание: стоковое
Цена вопроса: детали <500$ + доставка + работа.
Примечание: это самый популярный способ. Примерно 80% людей желающих проапгрейдить свой байк выбирают этот простой путь. Никакой фантастики и все можно сделать своими руками. Поршни Wiseco — хорошие и проверенные детали. Вы почувствуете реальный прирост мощности и момента. Большая часть людей покупает готовые наборы, содержащие два цилиндра, поршни и кольца.

ВАРИАНТ №2: ДЛЯ ГОРОДА ЛУЧШЕ НЕ ПРИДУМАЕШЬ

Итоговая мощность: 80 л.с (прирост в 30 л.с, по сравнению со стоком)
Итоговый момент: 80 Н•м (прирост в 37 Н•м, по сравнению со стоком)
Цилиндры: можно расточить существующие стоковые или купить от сторонних производителей.
Поршни: стоковые с Buell Thunderstorm
Кольца: стоковые с Buell Thunderstorm
Головки цилиндров: стоковые с Buell Thunderstorm (не модифицированные)
Распредвалы: стоковые
Зажигание: настроенный Screaming Eagle
Цена вопроса: 700$ + доставка + работа.
Примечание: этот способ апгрейда еще называется Thunderstorm conversion, так как в нем используются детали от заряженных байков марки Buell. Этот путь для тех, кто хочет оставлять позади более кубатурные твины.

ВАРИАНТ №3: ДЕНЬГИ НЕ ИМЕЮТ ЗНАЧЕНИЯ.

Итоговая мощность: 109 л.с (прирост в 58 голов)
Итоговый момент: 80 Н•м (прирост в 43 Н•м)
Цилиндры: никасилевые цилиндры 1250ссм.
Поршни: Nallin Hurricane (кованые)
Кольца: ???
Головки цилиндров: стоковые с Buell Thunderstorm (модифицированные)
Распредвалы: Screaming Eagle Bolt или Red Shift
Зажигание: Dyna 2000i
Карбюратор: Mikuni HSR45
Цена вопроса: более 2000$ + доставка + работа.
Примечание: ЭТО ПИЗ…Ц. Не обделайтесь. Есть другие наборы, дающие похожий результат. Советую посмотреть QC88 conversion на Sportster.org (http://www.sportster.org/tech/quad88/).

Цены довольно приблизительные. Во-первых, статья написана до кризиса, во-вторых, указанные цены скорей всего для Америки, т.е. не учитывается стоимость доставки в Россию.

Так какой же вариант выбрать?
Выбор пути апгрейда зависит от нескольких отличных друг от друга факторов.
Бюджет: как говорят, любую проблему можно решить, были бы деньги. Однако в реальной жизни, лимит по финансам ограничен. Есть хорошее правило: на апгрейд вы потратите больше денег, чем планировали. Обычно заканчивается тем, что вы поставите карбюратор, который давно хотели или задумаете покрасить головки цилиндров порошковой краской. Будьте уверены, бюджет апгрейда придется увеличить.

Ваш технический уровень: даже простейший апгрейд, требует инструмент и некоторые технические навыки. Если вы посещаете дилера всякий раз, как теряете открутившуюся гайку, следует рассмотреть вариант установки апгрейда в проверенной мастерской. А вообще, приведенные выше варианты не требуют наличия механического цеха или специального оборудования.

Время: я работаю с апгрейдом не торопясь. Если вы планируете закончить это за выходные, то можете быть разочарованы. Примите в расчет время, необходимое для обработки цилиндров и их головок в мастерской. Вариант №1 наиболее простой и поэтому самый быстрый. Вариант №3 наиболее времязатратный. Можно сэкономить часть времени купив новые цилиндры, а не растачивая стоковые. Это будет стоить вам дополнительно от 50 до 100$, но позволит завершить апгрейд быстрее, потому что не придется ждать изготовления деталей.

А что с надежностью?
Вариант №1 очень надежный – я не слышал о каких либо проблемах с ним, хотя встречаются сообщения о повышенной вибрации. Чем более радикально вы вмешиваетесь в конструкцию двигателя, тем более вероятна его поломка, но некоторые индивиды с конференций тюнинговали свои байки по второму и третьему вариантам, и, не смотря на то, что они постоянно ездят, не сообщали о каких-либо существенных механических проблемах. Однако у последних двух вариантов есть один побочный эффект: увеличение размера камер сгорания влечет за собой увеличение тепловыделения. Проблема решается установкой масляного радиатора с термостатом.
Какие поршни использовать?
Ed Greenwald пишет: устанавливайте кованые поршни Wiseco и забудьте про остальные варианты – наилучшая трата денег и никакой головной боли.
С другой стороны Axe пишет: я связался с поршнями KB – заэвтектический алюминиевый сплав менее подвержен тепловому расширению, поэтому можно работать с более жесткими допусками. Я установил допуск в 0,001 дюйма и сделал срез в 5 градусов на седлах клапанов, для улучшения потока. Результат великолепный! Скорость возросла, улучшился разгон, надежность не пострадала. Из-за течи в прокладке, не связанной с апгрейдом, цилиндры снимались два раза с момента его установки – задиров не обнаружено. Примите во внимание, что пробег на тот момент составлял 38000 миль, а апгрейд был сделан на отметке в 6000 миль. Лично я советую поршни KB. Один важный момент: особые требования к кольцам.
Crim пишет: облегченные поршни хорошая идея, если вы строите высокофорсированный двигатель. Если вы собираетесь пойти по этому пути, купите поршни для Buell Thunderstorm (поршни Wiseco легче, чем оригинальные).

Продолжение статьи читайте в английском варианте.
http://www.steele.com/dan/faq2.htm#_Toc9307749

Оригинальный текст.

883 to 1200 Conversion Guide and FAQ http://www.steele.com/dan/faq2.htm

Written and compiled by Dan Ratner

Version 1.6

Updated 4/15/2002 10:06 PM

Introduction 1

Upgrade Paths: 2

Upgrade Path One: BEST BANG FOR THE BUCK 2

Upgrade Path Two: STRONG STREET PERFORMANCE 2

Upgrade Path Three: MONEY NO OBJECT ! 2

Which path should I choose? 3

What about reliability? 3

What pistons to use: 4

What Cylinders should I use? 4

What about cylinder heads: 4

What cams should I use: 5

Regarding Ignitions: 5

What are these stage I,II and III mods that you refer to in this article: 5

What carburetor should I use? 5

So what do the terms compression, timing and octane rating mean and why should I care? 6

So why do I want a high compression engine? 7

What is the squish band? 7

What is Dyno Tuned Mean? 7

List of Suppliers: 8

A motley collection of unorganized posts regarding 883-1200 conversion topics: 8

END OF THE FAQ 18

Introduction

Many 883 owners choose to upgrade their stock engine to the larger 1200 cc version. This is the most effective way to increase your torque and horsepower. The stock 883 engine makes around 42 horsepower at the rear wheel. It is feasible to increase the horsepower to over 100 HP with the right combination of upgrades. This document is designed to enlighten and provide some rationale for choosing to upgrade your 883. It is by no means comprehensive and is a work in process.

Why did I write this document? Like many of you, I have some knowledge about engines and Harleys. However, I am quick to admit that in the overall scheme of things, I really don�t know shit. That is why I rely on the Sportster mailing list and sites like Sportster.org for valuable technical insight. The wrenches that inhabit these lands have years of experience and are quick to give advice. You would do well to listen to these sages. All of the information contained herein was culled from the XL-Mailing list sources.

Well enough ass kissing, lets get back to why I wrote this. Like many of you, I didn�t even know where to start with the whole conversion thing. There are so many variable that dumb asses like myself can quickly get lost in the terminology like gap, squish, angle, degrees. I started off collecting interesting posts in my inbox that were related to the upgrade. Eventually I cut and pasted these articles into a MS Word file. That file was the basis for this FAQ.

I have taken it upon myself to create three different profiles of possible upgrade paths (UGP�s). These paths are far from being perfect and simply represent possibilities. However, that being said, these combinations are installations that people have actually used in upgrading their Harleys.  I have also included a section that has some of the more frequently asked questions regarding an upgrade and some responses from people on the XL-Mailing list.

This document is designed to give you an overview. For detailed instructions on how to complete a 883-1200 conversion check out the technical archives at http://www.sportster.org/. This FAQ assumes you have done the basic Stage I upgrade to your 883 (ie, air cleaner, pipes, CV carb upgrades) [i] . If you don�t know what a stage one upgrade is or the �Harley Tax� then check out these articles http://www.sportster.org/tech/basic-perf/stage-list.txt and this article http://www.sportster.org/tech/basic-perf/harley-tax.txt

Upgrade Paths:

Upgrade Path One: BEST BANG FOR THE BUCK

Estimated Horsepower:       62 (20 over stock) [ii]

Estimated Torque                 72 (20 over stock)

Cylinders:                               Bore out your existing stock 883�s or buy 1200 sized cylinders

Pistons:                                  Wiseco #1655 (9.5:1 Compression)

Rings:                                     Hastings style (included with V-Twin kit)

Heads;                                    Stock 883 heads

Cam:                                       Stock 50 state cams (you may want to upgrade if you have a CA ver.)

Ignition:                                   Stock

Cost:                                       Parts <$500   + Labor

Notes: This is your bread and butter conversion. About 80% of people converting will choose this simple conversion. Nothing fancy and definitely a do it yourselfer. The Wiseco pistons are a tried and true system. You will see an undeniable increase in performance. Most people buy the V-Twin combo kit that includes 2 cylinders, pistons and rings. See the list of suppliers below.

Upgrade Path Two: STRONG STREET PERFORMANCE

Estimated Horsepower:       80 (38 over stock)

Estimated Torque                 80 (37 over stock)

Cylinders:                               Stock cylinders bored out or aftermarket cylinders

Pistons:                                  Buell Thunderstorm

Rings:             ?

Heads:                                    Thunderstorm (unmodified)

Cam:                                       Andrews N2

Ignition:                                   SE adjustable

Cost:                                       Parts $700     Labor ???

Notes: This conversion is commonly known as the Thunderstorm conversion. It uses parts from the high performance Buell (HD�s racing sister company). This is for the person who wants to blow most big twins off the road. You wont be the king of the hill but you will be pretty damn fast.

Upgrade Path Three: MONEY NO OBJECT !

Estimated Horsepower:       109 (58 over stock)

Estimated Torque                 86 (43 over stock)

Cylinders:                               Nik-a-sil 1250

Pistons:                                  Nallin Hurricane(forged)

Rings:             ?

Heads:                                    Thunderstorm after Nallin stage 3 modifications

Cam:                                       Screaming Eagle Bolt or Red Shift

Ignition:                                   Dyna 2000i

Carb;                                      Mikuni HSR45

Cost:                                       Parts $2000+            Labor ???

Notes: This is a monster. Prepare to be scared. There are also other packages that have similar figures. Check out the QC88 conversion on Sportster.org. This makes your sporty 1400+ cc�s

FAQ Section and Considerations:

Which path should I choose?

The upgrade path you choose depends on several different factors:

Cost � It is often said that any problem can be resolved by throwing money at it. However in a real world situation you won�t have a bottomless checkbook. A good rule of thumb is that you will end up spending more than you originally planned. Projects like these always end up influencing you to purchase that carb you always wanted or powdercoating your heads. Make sure to pad your upgrade budget.

The late John Pratt wrote: «The V-Twin kit #11-0473 includes 9.5:1 Wiseco reverse dome pistons, rings, pins and clips, 2 new 1200 cylinders with the pistons fitted and the head and base gaskets that set the proper deck height.» «The V-Twin kit lists at $460.39 Both kits will require a James top end gasket set #DS174303 that lists at $30.95.�

Your technical skill � Even the simplest upgrade requires tools and some mechanical skill. If you�re the type of person that freaks and runs to the dealer every time a nut rattles loose on your bike, you might want to consider having the upgrade done at a reputable shop. That being said, these upgrades are bolt on. That means that you don�t really need to have access to a machine shop or require specialized equipment to complete [iii] .

Maurice wrote:

[you need a]

3. A top end gasket set

4. Assembly lube, neverseize, and loctite.

5. Basic mechanics tools and a torque wrench.

You don’t even need a ring compressor that

disassembles if you install the pistons in the

cylinders on the bench and install them on the

rods together.

Yes, SURELY it IS that simple. Anyone who

has the most fundamental mechanical skills can do

it in a weekend, even taking two or three times as

long as a pro to be careful.

TimeIf you are like me, you work pretty slowly on upgrades. If you plan to do this in a weekend, you may be disappointed. Make sure to take into account time required to send head, cylinders etc to the machine shop to be worked. UGP1 is the easiest and therefore is the fastest. UGP3 would take the longest. One way to cut your time is to buy new cylinders rather than have them honed. This may only cost you an additional 50-100 dollars but will be able to complete the project faster because you have all the parts right in front of you.

What about reliability?

UGP1 is very reliable. I haven�t heard any problems with that upgrade. Some people do report a higher vibration. The more radical you make the engine, the more prone it is to breakdown. Not withstanding, several individuals on the list have bikes that are UGP2 and 3 that are daily drivers and they do not report any significant mechanical problems.

One common side effect of UGP2 and 3 is heat. Anytime you increase combustion chamber size you will increase heat. Most people combat this by installing an oil cooler with a thermostat.

What pistons to use:

Ed Greenwald wrote: Put in Wiseco reverse dome forged pistons and forget all the rest of the hop up ideas…Absolutely the best bang for the buck and you will NOT be disappointed.

On the other hand Axe wrote: I went with KB pistons, The hypereutectic alloy resists expansion so you can work with closer tolerances. Mine are set tolerance at .001″,and did a 5 angle valve cut (grinding down The hard seat for better flow) on the heads. Great results. Bike is fast, runs great, and is reliable. Due to (non-related) gaskets leaking, the jugs have been off twice since I did the conversion and there has been no scoring of the cylinders. And bear in mind that the bike has 38K miles on it, 1200 Conversion was done at 6K. Personally, I say go for the KB pistons. One note of caution, there are special specs for the rings.

Crim writes: Lighter pistons are probably a good idea [when building a high performance engine].  If you want to go that route, buy Buell Thunderstorm pistons (the Wiseco ones are lighter than HD [stock]) and have them mated to the quench band in the combustion chambers and port the heads.  This combo could very well be over 90 HP.  Definitely mid 80’s at least.

What Cylinders should I use?

[still need info]

What about cylinder heads:

Julie K. Balassa wrote: Whether your off the shelf T-storm heads make 90 hp depends on how they came off the [assembly] line.  Many stock heads, T-storm or other, are far from perfect — ports are not straight or have other imperfections, etc.  Depending on the combination of heads and cams, stock T-storm heads can make hp in the low 80’s into the 90’s. If you want to be sure that you get the most out of them, take them to a reputable head person [someone that modifies cylinder heads] and have them cleaned up prior to installation.

Crim writes: 1200 heads are pretty lame from a performance standpoint. No one uses them at all.  TS heads are definitely the way to go BUT you MUST get pistons to match.  A less expensive way might be to buy a set of SE heads. These heads are basically Buell Lightning or 1200 Sport heads.      Don’t get the dual plugged ones. N4s or N8s will work well with these.

Another route is to buy used 883 heads and send them off to HeadQuarters.  They’ll do a great job of porting them and you can still use your stock pistons.  They even have a set of cams that are specially designed to work with their heads.

If you want a REAL rip snorter, buy a set of Nallin Racing TS heads and pistons and use SE kit cams.

Crim also wrote: Don’t waste your money on dual plugs.  They are very effective on the ironheads because of the deep combustion chamber and high piston dome.  But Evos use flatter pistons and have chambers that don’t shroud the spark.  Dual plugging an Evo Sportster is a waste of money.

>I have been told that the Screaming Eagle Heads and the

>Buell Thunderstorm heads are made from the same cast.  Is

>this true????

They are very similar but different.  The combustion chambers both have a quench shelf.  When used with a piston that mates up to that shelf, they are very efficient heads.

Problem is the SE (same as 1200S or Buell Lightning) heads are typically used with flat top pistons and therefore don’t take advantage of the design.  None the less, SE heads can easily support 80+ HP.

Thunderstorm heads have bigger valves than SE/Sport/Lightning heads and a bigger combustion chamber as a result.  Therefore, domed pistons must be used to maintain a proper compression ratio.  All in all, the Thunderstorm set up is much better for a true «bolt on» set up.

883 heads may produce better low end power because the valves and ports are smaller than those on the T-storms.  If you want all out, big top end numbers, I think ported T-storms are he way to go.

What cams should I use:

Choose a cam that is appropriate for your purposes. Personally, I don�t feel there is any point spending money on a cam if you aren�t going to see a noticeable �seat of the pants� improvement over what you have already. For many of the exotic cams, you won�t feel any improvement unless you drive beyond 5000 rpm. In fact, some of these cams actually lower your low RPM performance to increase the top RPM performance. Since most driving occurs at the low RPM range, I am sure you can see why these cams are reserved for owners who are looking to wring every possible HP out of their engine no matter what the cost.

The stock 50 state cam is somewhat restrictive due to emission controls. The N2 cam by Andrews is the most popular aftermarket cam that is available for Sportsters. It works very well with the UGP1 and 2.

Mose Levy wrote: The N2, IMO, is the best street cam available for STOCK / STAGE I applications. It is NOT, however, compatible with high compression applications.

For UGP 1 you can get away with using the stock cam. If you are one of those unfortunate souls that has a �California� cam then you might want to upgrade to the N2.

John Nelson wrote: I noticed on your 883-1200 FAQ page you state that California models

have different cams. I researched this before I did my conversion and I

concluded that all (49 States and California) year 2000 883 and 1200 models

use the same cams. The 1200S models uses a different cam, but the same all

50 States.  I believe that some early 1990’s California models had

California only cams, but I don’t know the exact years.

Regarding Ignitions:

Crim writes: As for the ignition, HD ignitions are pretty good as long as you get the SE module with the correct curve for your set up and riding style.  Check the archives for that info. I’ve never messed with ignitions……. yet

What are these stage I,II and III mods that you refer to in this article:

These modifications are standardized upgrades for your Sportster. Check out the technical section in at Sportster.org and click on the link �What are Stage 1/2/3 modifications?

What carburetor should I use?

A lot of people on the list ask questions about carburetors. Advertisers would suggest that you should upgrade your carb immediately. My suggestion is that you save your money. The stock CV carb is a pretty good carb by most accounts.

A lot of aftermarket carburetors are designed for high performance engines. Similar to cams, the more performance oriented the carburetor the less it helps you on the low end of the RPM spectrum. If you choose UGP1 or 2 keep the stock carburetor.

Read these tech articles for more info about the CV carb:

http://www.sportster.org/tech/basic-perf/poorman-mod.txt

http://members.aol.com/roundr1/CVK40.html

Crim wrote: The only thing you’ll gain from the Mikuni is throttle response.  It’s nice to have but kind of expensive.

So what do the terms compression, timing and octane rating mean and why should I care?

By choosing UGP 2 or 3 you will modify your compression. UGP 1 keeps your compression similar to stock.

The following was shameless plagiarized from another website and was written by Christopher Martin. It is an excellent overview of the concepts:

Compression is exactly what it sounds like, the reduction of the volume of the intake mixture by a certain mechanical ratio. The ratio is dependent on the construction of the engine incorporating the bore, stroke etc. and final volume of the combustion chamber. A 9:1 engine reduces 9 volumes to 1 volume. This compression creates heat -called the heat of compression.

The fuel-air mixture is intended to withstand this increase in heat without self igniting or detonating in a gas engine; instead undergoing controlled ignition by the timed introduction of a spark. A diesel engine depends upon the intake mixture igniting solely due to the heat of compression. The higher the compression ratio the greater the utilization of the energy released by combustion.

Octane rating is intended to quantify a comparison of the particular gasoline to pure octane -the liquid form of straight chain eight carbon saturated hydrocarbons. This liquid was given the rating of 100 (100% octane) early on in the research of internal combustion engines and fuels because of its excellent ability to resist detonation due to the heat of compression. A given gasoline motor fuel is given a rating (as compared to a mixture octane) based on the average of two «measures» of it’s ability to resist pre-ignition. The research method -what all the equations say should be it’s «octane rating»- and the motor method -an actual test of detonation due to mechanical compression of the mixture- are averaged to create the octane number posted on the pump labeled R+M/2. Ether, used as starting fluid, self ignites all the way down to 3:1 compression -the practical lower limit in construction of an internal combustion engine.

Timing refers to the adjustment of the points during the compression stroke at which a spark is introduced to ignite the intake mixture. If the fuel-air mixture could ignite instantaneously and fuels with precise octane ratings were available to run in our perfectly constructed engines timing would be permanently set to top dead center «TDC», where the piston is at the exact top of it’s stroke and the charge is fully compressed for maximum power and efficiency. But in our less than perfect world it takes an imprecisely known amount of time for the flame front to propagate throughout the mixture of less than perfectly rated fuel and air compressed at something close to a 8:1 ratio. Therefore we are forced to set our timing for something in advance of TDC in most cases, and then use various measures (vacuum, centrifugal force) to determine engine speed and farther increase the «advance» and higher RPM.

Uncontrolled or improperly timed ignition reduces efficiency and can destroy an engine. Detonation/pre ignition can occur at odd locations inside the combustion chamber creating stresses for which the engine wasn’t designed. Pre-ignition or improper timing also can cause the force of combustion to peak while the engine is still trying to compress the mixture. Excessively late ignition lowers engine power and causes too much heat to be transferred to the cylinder walls.

Summing it up;

The greater the compression the greater the heat of compression and need for fuels resistant to detonation or pre-ignition.

The greater the speed of the engine the farther in advance of TDC the spark must be introduced to have ignition occur at the correct point in the piston’s motion for maximum efficiency.

The higher the octane rating of a fuel the slower it ignites.

The lower the quality (or reliability of the quality rating) of the fuel the farther from peak efficiency timing should be set for controlled ignition.

So why do I want a high compression engine?

Art wrote: You don’t, necessarily.  However, higher compression will (usually) give you more bottom end power & quicker acceleration w/ less ignition timing advance. Realistically, 10.5:1 is the  limit for street engines, due to the octane of available pump gasoline.  10:1 gives a better safety margin, although a very well designed street engine «can» run up to 11:1.

What is the squish band?

Art wrote: The squish band is the area around the outside of the piston which is relatively flat, or closely matches the shape of the head.  That’s where the distance from the head to the top of the piston  is significantly less than in the center.

«Squish» does 2 things:

1) helps improve fuel-air mixing on the compression stroke as it forces most of the mixture into the combustion chamber and;

2) cools the burning mixture & gasses on the exhaust stroke.

The popular reverse-dome pistons increase the combustion chamber area, while decreasing the squish band around the edge of the piston, concentrating the mixture closer to the spark plug while still providing a decent compression ratio.  For more compression, flat-top or domed pistons are used, but care must be taken to not raise the compression ratio too high, unless you’re dealing w/ an all-out race engine on race fuel, where octane rating is not a concern.

Also, different cyl. heads require different pistons.  The reverse-dome pistons work fine w/ stock or modified 883 heads, but when using 1200, SE or Thunderstorm heads, matching pistons must be used as well, or both the compression ratio & squish area will be wrong.  For example; using reverse dome pistons w/ Thunderstorm heads would result in a very low compression ratio & almost no squish, as the T-Storms have a much larger combustion chamber, while using flat-top pistons w/ stock 883 heads would result in too much compression & a large squish area, as the 883 heads have a much smaller combustion chamber.

Both compression ratio & squish area are the direct result of the match (or mis-match) of the piston top to the shape of the inside of the head & the distance between the 2 @ TDC.

What is Dyno Tuned Mean?

When individuals want to find the maximum horsepower they can achieve given a particular set up they turn to the professionals. Here science takes over and the motorcycle is placed on a machine called a dynomometer that is half treadmill, half computer. The motorcycle is run through a series of tests under stress or load that simulates real world conditions. Results of these tests are graphically displayed on a two graphs sharing the same chart. The curves are referred to as the HP curve and the torque curve. By manipulating air/fuel ratio, a professional tuner can graphically see what produces the most power and torque. This takes the guess work out of trying to figure out what jets you should use in your carburetor.

Dyno�s are very expensive so you just can�t go out and buy one. However larger repair and performance shops have them and will usually rent you time on them by the hour.  Make sure to find one that �standardizes� it results.

List of Suppliers:

The V-Twin conversion kit is available at major independent Harley shops everywhere. You can try Zoom Cycles at 888-316-1994 if you want to do mail order.

Wiseco web site is www.wiseco.com . Look for the Harley catalog on the bottom of the page. The catalog is in PDF format so it may take a while to load.

Screaming Eagle products are sold through Harley Davidson dealers. Very few dealers have online shops. Try Van�s HD in NY www.vanshd.com, Surdyke www.surdyke.com or Chicago HD www.chicagoharley.com/ . Order online and you will usually get a discount.

.

Info on Andrews cams can be found at www.andrews-products.com.

Thunderstorm heads are available through Harley dealers. You may need to refer to them as Buell heads.

Headquarters is a performance shop that specializes in high performance heads. http://www.head-quarters.com/

Zippers, another high performance machine shop. http://www.zippersperformance.com/

A motley collection of unorganized posts regarding 883-1200 conversion topics:

[thanx Dave in VA for compiling the majority of this info]

—————————1200 CONVERSION ( AND PISTONS)————————————

Listers, I was emailed by some members about a piston thread. I will attempt to answer the questions. First, KB is a subsidiary of United Engine and Machine, also known as Silvolite, DuAlloy and  Claimer since 1922. We do cast, forged and hyper pistons. We do 20,000+ a day here in Carson City, Nv and Mexico. Some of you use our pistons and don’t even realize it. Amoungst internal combustion engineers, it is a well known fact that a forging does not belong in an air-cooled, street bike. Absolutely no OEM, from harley to Ford uses a forging. Every OEM in the world of any size uses a hyper piston. A hyper is a cast piston with a silica content over 12%. Silica dissolves in aluminum up to 12% then it migrates in to the matrix as tiny particles. These particles act as a thermal barrier and the bearing surface because of their hardness. Hypers conduct heat at a rate 60% less than any other alloy and expand 15-20% less. These thermal properties are highly prized by designers and good tuners. The downshot of a hyper is the manner of the destruct mode. It will last almost 300 degrees longer than any other alloy but when it gets within 100 degrees of the melt point it will get weak and crack into pieces. Hypers have no ductility. Forgings, on the other hand, have ductility and no thermal properties. Regular cast pistons have very little ductility and just a little thermal advantage. I design forged pistons for the automotive industry also. A forging in a water cooled motor acts totally different than one in an aircooled. This can be explained by just looking at the thermodynamics of  the cylinder. In a harley cylinder, most of the heat is at the top of the cylinder, near the combustion chamber. This is also where all of the cylinder mass is at.

To try to counteract this problem, harley went with the aluminum cylinder that achieves torque with heat. It proved helpful but not a complete fix, the cylinder still expands more and faster at the top. The next step was to use a full hyper piston and piston oilers in the twincams. The oilers do not lube the piston, they cool them. This made the motor highly tunable for Harley. Finally, as with us, forgings are necessary in both the MC and automotive world. The current need for forgings is their ease of manufacture. Out of one die, 20-40 different piston types can be made. KB could not survive without making forgings for the auto market but I refuse to make them for the aircooled market. It has been said, «those who chatter a lot learn nothing, those who listen a lot learn much». I say this because I have seen experts, incuding me, raked over the coals on this and other sites. The above FACTS cannot be disputed. It is my job, not my hobby. Most of you ride a bike with motors I had a hand in designing. Some of you know who I am. This is my last attempt at adding some insight to this site, hope someone appreciates it. Logic should be used when someone tells you that they got bad gas, kept riding with it, destroyed a piston and then fixed it with another brand. I showed that post to a friend at harley and it got quite a laugh. I could quote thousands of high performance builders, auto and MC, that would swear by hypers. If a builder ‘NEEDS’ forged to get his motors to survive, it proves he’s not much of a builder and needs a very ductile piston to make his motors survive. I have 1 out of 14 pans that has forged pistons. At the time I built it there were no hypers of that size(4″). I used long rod chevy forged and it runs as expected and I won’t switch them to hypers till it needs rebuilt. One problem in this industry is the fact that KB is not the only company making hypers. KB does make the highest silica, T6 hypers around but several companies make hypers. Even the company that owns that other company(starts with W) just bought the premiere hyper piston company in Europe-Vertex of Italy. Sorry, got a meeting to attend.

Ron McBroom(Panman)

D-Ron

Enterprises KB Pistons

———————————-

-Date: Fri, 13 Oct 2000 16:01:50 -0700 (PDT)

From: Maran Wilson <>

Subject: Considering the 883>1200 conversion

all right, since I need to take off my rocker boxes to fix the leak, I figured that I might as well make a weekend (or three) out of it and do the 883->1200 conversion while I’m in there. Still gotta get permission from the wife to spend the $ (wish me luck) but here’s what I’m planning at this point:

1) V-Twin 883->1200 kit that comes with wiseco «no head

work» 9.5:1 pistons, cylinders, and gaskets.

2) Andrews N2 cams. (NOT using bartel’s thin base gasket.)

Unless someone wants to sell me your stock, model year

2000, cams from a non-california bike.

From what I can read in the archives, this setup should

give me the best possible torque numbers in the low to

mid rpm range. That is how I ride, and I don’t give a

f**k about what happens after 5000 rpm cause I’m pretty

much never gonna be there. The only reason for changing

cams IMO is to get rid of those «special» California

cams. In fact, If someone has a set of non-california

model stock cams that were taken off a 2000 model without

many miles, I might be willing to just buy those for a

good price instead. Anyone? Pre 2000 models need not

apply since the cams ARE different for 2000.

Anyone know if the heads are different for California

bikes or not?

Could you ping me off line or otherwise if you have done

this same conversion (especially using the V-Twin kit)?

I’d like to get a little more info before I start ordering

parts. I understand everything else on the bike can be left

stock including lifters, push rods, valve springs, heads,

ignition module, coil, etc.

Thanks,

-Maran

’00 chrome yellow 883

—————————————-

Personally, I’m gonna hold off on ignition upgrades until after the

conversion and then see whether I need to upgrade or not. I don’t think the ignition adds much, if anything, in terms of Hp or Torque but it may be needed to smoothen out the engine and possibly curb pinging. As for deciding on cylinder/piston kits, I went down the following

road: v-twin 883>1200 kit — $392 (comes with cylinders, pistons, rings, gaskets, etc and

no head work is required.) rocker gasket set — $35 andrews n2 ’00 cams — $230 (since CA

models have «special» cams) *all parts were ordered from at those prices. For me the

decision was easy since it is cheaper than all the other options that require new or

modified heads AND the smaller flow of the 883 heads increases low end torque. Thunderstorm

and other high flow heads will get you sexy high rpm HP numbers, but I don’t

think they do as well in low to mid (i.e. 2000-4000) rpm range where I spend almost all of my

time driving. On the other hand though, if you routinely rev her up to 60 mph in

second gear, then you might want to choose the T-storm heads since they pack a bigger

punch at those rpms.

——————————————

Noface sez:

I’ve been thinking about adding T’Storm Heads, w/

Wiseco, JE, or Keith Black pistons, Andrews N8’s, and

a Crane HI4e single fire ignition.

<SNIP>

There are a few T-storm conversions running around out there that are

EASILY over 80 HP. Not too shabby. I wouldn’t put a high priority on

the ignition unless you get BAD pinging.

There are several reputable head porters that are really impressed with

the results they get from ported 883 heads. This guy (Doug) from

Headquarters in Toronto Canada claims to get 90 HP from his ported 883

heads, stock cams and stock 1200 pistons. Larry Hardy at Performance

Techniques in CA also really likes the 883 heads.

It seems the small 883 ports lend themselves to handcrafted porting.

They can be made into what ever shape/size the porter wants.

Interesting idea…

Crim & Diablo Debbie — ’99 Sportster 1200S

——————————

Date: Mon, 23 Oct 2000 13:09:45 -0400

From: «MarkB» <>

Subject: Re: 1200 heads

> Contemplating doing the 1200 conversion this winter. Should I bother

buying

> 1200 heads or having the 883 heads ported with 1200 valves installed? I

> prefer more torque than horsepower. Also is replacing the cams worth it

> without doing any headwork?

Barney,

I did the conversion last winter and ended up with a very

torquey motor — which is what I wanted.

I kept the 883 heads and had only valve work done. No

porting, same valve size. Ping me off list and I can send

you a ZIP file with the parts I used, prices I paid and

before and after dyno results (883, 1200, 1200 w/ THeader).

I believe that 1200 heads or reworked 883 heads w/ 1200

valves *may* give you higher numbers, but they will be

more toward the top end. Likewise with the TStorm heads.

Just a matter of personal preference, really.

Bernie

1999 XLH 883->1200

LSR Team Member

—————————————-

Is there anywhere you can buy a kit to do the conversion. I can get it done

>at a local shop for $650 and I was wondering if I did it myself if I could

>save a little money..

I had this saved way back when I was thinking about the conversion. This

information was posted by John Pratt: «The V-Twin kit #11-0473 includes

9.5:1 Wiseco reverse dome pistons, rings, pins and clips, 2 new 1200

cylinders with the pistons fitted and the head and base gaskets that set the

proper deck height.» «The V-Twin kit lists at $460.39 Both kits will require

a James top end gasket set #DS174303 that lists at $30.95. The XL list cost

is 15% off the list price for any of the kits and gaskets.»

So, it seems that you might save yourself a couple hundred or so. But

you’ll need to buy a torque wrench if you don’t already have one, which will

add anywhere from $25 to $125. I’d say do the conversion yourself if you

like to wrench. Nothing beats the satisfaction of riding a bike with a fresh

conversion, knowing you did it yourself!

Bob O 2K Hugger >1200 Lightning ( did it myself ) UP of Michigan

—————————————

I have a 94 883, mostly stock w/ exception of Screamin Eagle Hi-Flo Kit

And Python pipes. I am considering doing the conversion (or paying to have it

done). How much more horsepower/torque can I expect? I am planning on

using the Custome Chrome Kit w/wiseco pistons, and I do not wish to put in cams

at this time. Will I see a significant difference? I have heard many

diffrent opinions on the conversion. Some say use «cast» pistons and bore out my

883 cylinders, some say get the new piston and cylinders to match (wiseco).

Some say you have to put in cams or it will not run right. What is the least

expensive and most efficient way to do this?

Thanks for any answers..

Kevin my freind

Put in Wiseco reverse dome forged pistons and forget all the rest of the

hop up ideas… Absolutely the best bang for the buck and you will NOT be disappointed.

I used to liken my 883 to a sowing machine. It kinda nicely moved downt

the road with a smooth acceleration. Now she moves like a Singer with a rocket up it’s ass.

Don’t waste money on new ignitiion.

Ed Greenwald

——————————

From: «Moshe K. Levy» <>

Subject: Re: Cams and drag pipes

Message-ID: <>

Content-Type: text/plain; charset=us-ascii

— Steve Lange <> wrote:

>>>I usually cruise between 2000 and 3000 RPM, with

the super slab seeing around 3500 (~ 70 MPH). So my

question is: Would there be any advantage to changing

cams on my bike when I convert it over to a 1200? I

figure a new ignition module might be nice, but not

necessary. It just needs a little more power, and I’m

not planning on racing the bike.<<<<

You were correct in the «tradeoff» analysis with

regards to cams and pipes. Drags produce power in the

high rpm band, AT THE EXPENSE of your low and

midrange. Many cams produce high end power, AT THE

EXPENSE of your low and midrange. The latter can be

offset with a bump in compression. There is one set of

cams, however, designed to work with stock compression

applications, which REALLY wakes the engine up under

3,500 rpm — the Andrews N2. See

— that’s the N2 vs. the popular N4 / SE bolt in cam.

Notice WHERE the power is produced. The N2, IMO, is

the best street cam available for STOCK / STAGE I

applications. It is NOT, however, compatible with high

compression applications. I would definitely spend my

money and time on cams before swapping ignition

modules…

-MKL ’98 1200C

—————————-

«Seems to me that this would be a really

trouble-free bike if it weren’t for that idiot that keeps working on it…»

Those push rod tubes are a bitch until you get the hang of them. One gave me

a rough time when I did my conversion back in Sept. Once you get it leak

free you’ll appreciate your accomplishment. I hear where you are coming from

Dave. Good luck!

Here’s a tip I got from Dale:

«A new lower seal is really tough to get seated..it

almost takes 4 hands. With the seal pushed up into the

lower collar, the metal piece that seats the lower

pushrod,…get the alignment hole lined up & seated in

the little pin..as you push down to seat this side

where the alignment pin is, you will notice, an

opposite side of the lower collar raising up..& this

is where the seal will get pinched & leak if you go

ahead & torque the allen bolt of the lower collar.

While holding one side, usually where the alignment

pin side is, then start the allen bolt in & screw it

down by your fingers until it contacts the lower

collar, without going further. Then take a 3/8 drive

extension & with the square end, push down on the

opposite side of the lower collar that is trying too

raise up. The other side where the alignment pin is,

should stay put once you finger tighten the allen

bolt. While pushing down with the extension, go ahead

& tighten down the allen bolt with your other hand

using an allen wrench or hex drive or whatever you use

or prefer. I use Ball end allen wrenches too spin

these type of fasteners down, then torque with a hex

drive. You will find the lower collar should stay in

an even position where one side does not raise up

while trying to torque down the allen bolt. This

should let it all seat even on the seal without

pinching a corner or section of it causing a leak.

It may take a little experimenting too see this &

what I am describing, but I think if having done

these, you will know what I am talking about.»

ride safely, RED

southwestern, CT

99 883/1200 XLH std.

Motorbreath the corner carving tractor

—————————————

Milling the heads does NOT improve squish.

Because the chambers are domed shape,

milling does SLIGHTLY, and I mean VERY

slightly, make the chamber diameter smaller,

which increases the squish area, but once again,

that is VERY slightly.

As it is, you’ll have a 1/4″ wide band of squish

around the 3 1/2″ bore. Milling .025″ would make

that squish band maybe .001-.002″ wider. And

it would raise compression significantly without

really improving the squish.

The important factor in squish is the height, the

distance between the piston and the squish band

on the head. Assuming a flat head deck, this is

determined by the thickness of the head gasket

and the deck height of the piston… i.e. how much

it is above or below the cylinder when the cylinder

is bolted down and the base gaskets are smashed.

There’s a manufacturing tolerance, but on average,

the piston is pretty much level with the cylinder when

it is snugged down finger tight, so when all the torque

is put on it in final assembly, and the base gaskets

crush .002″ or so, the piston will be above the cylinder

by .002″. If the head gasket is the stock .052″ one,

the squish height is .050″.

This is unacceptable for good squish. It should be in

the .025″-.035″ range when cold (the cylinders grow

when hot). If you use a .027″ copper Bartels head

gasket with the stock base gaskets, squish, ON AN

AVERAGE engine, should wind up about .025″.

With a .032″ gasket, it’ll wind up about .030″.

You have to remember that doing this also raises the

compression. In the case of the .027″ head gasket,

compression winds up about 10.2:1 and with the

.032″ gasket, it’s about 10.0:1. This should give good

low end torque as well.

Maurice

—————————-

> After I upgraded my engine to 1200 and kept the original heads. I feel

that

> the engine is shaking and vibrating much more than before.

Did they retard the timing when they did the conversion? With the higher

comp. ratio and bigger bore, the 883 ignition would be way too far advanced.

If you have a timing light, try retarding it 3 or 4 degrees and then going

for a ride. If it feels like it’s vibrating less, have the timing set on a

dyno or by an expert, and you may have found the culprit. I have heard lots

of people say that they ended up needing the 1200 module to get the

vibrations to stop, but others who had good results by just retarding.

Good luck

Dave

—————————-

The 1200 cranks are balanced for the weight of 1200 pistons. Wiseco pistons

weigh about the same as stock 883 pistons. I use stock 1200 pistons in a

883/1200 conversion. No ill effects. These motors aren’t very presicely

balanced anyway. The main source of vibrations in a conversion are a result

of the 883 ignition curve. Turn the timing back, look for a cast off 1200

module (that’s what I did, or buy a Dyna igntion.

Sportyeric

92XLCRS1

——————————

Date: Sun, 9 Dec 2001 12:55:08 -0500

From: Maurice Riggins <>

Subject: Re: 883/1200 conversion pricing

Message-ID: <>

Content-Type: text/plain;

charset=»iso-8859-1″

> S.E. cylinders

That’s fine… you can also have your

883 cylinders bored for a little bit less

> 1200 cc Teflon coated piston kits

Bad. These are the stock 1200 pistons…

they are WAY heavier than your 883 pistons,

and will increase vibrations and lower the

rpms at which they occur. You will probably

resort to higher belt gearing to help

relieve them.

> S.E. Performance heads

If you don’t ride over 4,500 rpm,

(see

to find out what mph that is in each gear)

these are a waste of money. If you do ride over

that speed a lot, Buell Thunderstorm heads are

a lot better for about the same price.

> S.E. bolt in hydraulic cam set

These are also high-rpm cams. Waste of money

if you don’t ride over 4,500 rpm.

> Tappet assemblies (4)

Stock tappets are fine, but the one’s on an ’86

are probably pretty tired by now… depends on

the mileage.

> Top end gasket set

That’s fine.

> S.E. adjustable pushrod kit

Huh? You sure you aren’t looking at a Big Twin

setup. I didn’t know SE made adjustable pushrods

for XLs. At any rate, you don’t need them.

> S.E. ignition module

(includes harness for earlier bikes)

If you’re doing the high rpm setup, fine. If

not, keep the stock module.

> Oil & filter change

Should do on an engine rebuild.

If you don’t ride over 4,500 rpm, just do the

typical 883/1200 conversion. Keep your stock

heads, carb, pushrods, cams, and buy SE cylinders

for $260 minus 20% mail-order at Chicago HD and

HD top end gasket kit (about $60 mail-order) and

use the K1655 Wiseco 883/1200 conversion piston

kit, $230 retail… less than $200 mail-order.

The labor for the conversion, without doing cams,

should cost about $400.

If you do ride over 4,500 rpm, a cheap bolt-on

setup would add the Thunderstorm heads, and SE

bolt-in cams and ignition (and cam cover gasket

and seal)… all available at 20% off at Chicago

HD, substitute Wiseco K1700 Thunderstorm pistons

for the K1655 883/1200 pistons, and add about

$100 to the labor to install the cams.

To whoever was concerned about piston noise…

when the piston to cylinder gap is no greater

than the range Wiseco recommends, .002-.0025″

there should be no significant noise once the

engine has warmed up. They do run more gap

than cast pistons (.0015″) but expand more, so

wind up with the same when hot.

DON’T do the old-style flat-top piston/grind the

883 head Harley conversion! You wind up with NO

squish and higher compression for an engine that’s

more likely to ping, not to mention will vibrate

more.

Maurice

——————————

I like mine.

Wiseco reverse dome 9.5:1 pistons, bored cylinders, stock 883 heads, N2

cams.

You might want to keep stock cams. I get a few more ponies and lbs (70/70),

but I had to retard the timing a bit to keep pinging at bay.

Vibration is LESS than stock 883. It used to begin to bother me at 65-85

MPH in fifth gear; now I cruise at 80-85 with no complaints, even with stock

883 gearing.

-Jake near Nashville

—————————-

<<If I do a Wiseco 9.5 to 1 1200 swap will I have to

upgrade to an XHL-1200 ignition module? If so will

any of the aftermarket modules (Crane, Compu-Fire,

Dyna) work in my 2002 Sporty. All the mail

order people cannot tell me yay or nay! My local

Harley place was nice but completely ignorant. HELP,

thanks.>>

No you will not have to go to a 1200 module. Lots of

folks are riding around with 883 modules in 1200

conversions. You get more RPM also with a 883 module.

It’s limiter is 6000 compared to 5200 of a 1200. Try

it as it is & se what you think. You can always

install another ignition later after conversion.

I have a bunch of ignition curves graphed out at my

webpage. See the link below to get to the webpage.

=====

Dale A.

Rattler..95 883-1200

01 883-1000 Hugger aka «Mystery EVO» 1000 cc P/PP Record holder @ 143.079

MPH

«When everything is coming your way, you’re in the wrong lane!»

—————————

I’m not a tech-head, so please clarify for me. If I

have installed a

custom

chrome 10:1 conversion kit (wiseco dished pistons new

cylinders, and

gaskets) in a stock 883 head set-up (stock cams too)

do I have a 10:1

compression set-up?

Keep in mind, all vendors are using «mechanical

compression» when they talk about these set-ups being

a certain compression set-up. This is a non changing

physical»value’ based on cylinder volume in cc’s, head

volume, the cc’s of the gasket slice — the space the

gasket is occupying, & the distance the top of the

pistons are from the top of the cylinders, wether this

is a neagtive value or positive depending on if the

piston deck sticks up out of the cylinder at TDC or

are recessed below the cylinder…otherwise known as

«deck height». Changing cams affects the «corrected

compression» or for lack of a better term that escapes

me right now, the «real compression» that is actually

making power.

In your case see below:

1. 3.498″ standard cylinder bore

2. with Wiseco K1682’s(10.0:1) with a dished dome of

— 8.5 cc’s

3. assuming standard HD head gasket = .052″

4. assuming deck height of .003 with stock HD base

gaskets(pretty standard for stock 1200 flat tops)

although you have Wiseco’s, should be near same, if

base gaskets are stock HD.

5. 883 head volume = 49.5 cc’s

Then your mechanical compression is: 9.9953…yep, I’d

say you have 10.1:1 mechanical compression.

Your «corrected compression» with stock cams is:

9.1607…..you have a good screamer here IMO!

<<I can pick up a used set of 1200 heads for $250,

with 1k on them. Would this be cheaper then having the

883 heads fitted with 1200 valves, and do I need to

have the 1200 heads tweaked?>>

Changing to stock HD 1200 heads with it’s wide open

combustion chamber would induce a detonating nightmare

engine at this mech. compression IMO with stock cams.

It would also drop your mechanical compression to

around 9.5:1 due to more cc’s of the 1200 combustion

chamber. I would stick with going with the 1200 valves

in the 883 heads. The 883 head chamber is better

designed for this, the 1986 model 883 bathtub head

chambers are better yet. A local machinist charged me

150 bux for this on a set of 883 heads, your cost

should be near this I would think. You would gain a

cc or two in the 883 head chamber doing this as you

would want the 1200 valves «unshrouded» some to take

advantage of flow. The machinist would cut back into

the 883 valve seats to install 1200 valves thereby

«shrouding» the edges of the 1200 valves by the head

chamber metal. The gain in head cc’s should be offset

by the gain in head flow. Increasing head cc’s would

change the mechanical compression slightly to a lower

value.

Dale A.

Rattler

———————————

John Casale wrote:

> I am in the middle of my base gasket job and have a few questions:

>1. On page 3-14 of my FM it says » Rotate the crankshaft until both

>valves are closed on the head being repaired.» How do I do this?

>2. On page 3-24 the FM says » Turn engine over until one piston is at

>bottom of its stroke.» How do I do this and if the piston is at the bottom

>of its stroke will I have a hard time removing the ring set?

><SNIP>

>Any finally, are there any tips for easily removing the damn shifter lever?

<SNIP>

Hello John,

Best way to rotate engine so both valves are closed is following:

Lift bike so rear wheel is off the ground. If you don’t have a bike lift,

you can use a floor jack with the bike on the kickstand, lifting very

slowly and carefully and only high enough to be able to rotate the rear

wheel. Put the bike in 5th gear, and remove the sparkplugs. Do one head

at a time. Doesn’t matter which one you start with, but say you start with

the front. Bump the rear wheel in the direction of rotation. Piston will

rise twice during each 4-stroke cycle, once on the exhaust stroke to top

dead center overlap, and once on the compression stroke to top dead center

compression (TDCC). At TDCC, both valves are closed. You’ll know you’re

on the compression stroke because as the piston rises, you can feel a

strong burst of air if you put your thumb over the front sparkplug hole.

You can also use something non-intrusive like a plastic straw, insert it

through the sparkplug hole to rest on the piston crown, and watch it rise

with the piston as you bump the rear wheel. This is a good way to determine

when the piston is at the very top of its stroke. Just be careful to not

et the straw get stuck or break off. I’ve done this often and never had

anything go wrong. In order to remove the cylinder, the piston must be

down a ways or you won’t have enough clearance to get the cylinder off, but

up enough so you can hold onto it and stuff some rags into the crankcase

bore. This is crucial as you don’t want any debris, broken rings etc.

dropping down into the crankcase. You also need to hold on to the piston

so it does not bang against the cylinder studs. This is also crucial as

the studs are fragile and can easily develop indescernable stress

cracks. Before you remove the cylinders, cut 8 pvc or rubber hose pieces

to slide over the studs. IF you use rubber hose, I find it helpful to

split each piece, makes it easier to slide over the stud. Rock the

cylinder gently to pull it off the piston and studs. As soon as it’s up

high enough to expose the crankcase bore, check that there’s no debris on

the crankcase surface and then stuff some rags into the bore. As soon as

you have the cylinder off, slide the pvc or rubber hose pieces over the

studs. If the piston is too high or low to work with at any time during

the job, you can always bump the rear wheel to move it, just be sure to

hold onto it so it doesn’t flop around. Repeat for other cylinder. As

soon as both cyls are off, let the bike down off the jack. If you have a

lift, you can leave the bike up off the ground for reassembly. In the

interest of keeping this reply to some reasonable length, I’ll let someone

else reply about head inspection and cleaning. Your service manual has

pretty good instructions for how to inspect the various parts. To remove

the shifter, gently tap the tip of a large flat screwdriver into the slot

in the arm. This will spread it enough to get it off the splines of the

rod. Be gentle or you’ll crack the arm or damage the splines. Good luck!

——————————

— General Jinjur <> wrote:

<snip>

> Do you have to buy the cylinders and then very

> carefully measure them in

> order to select a piston? I’m sure I don’r have

> anything that will

> measure that accurately.

John,

Wiseco makes standard size pistons that will fit the

stock bore.You could buy the stock bore pistons and new

cylinders, and more than likely the tolerances will be

fine. Wiseco recommends tolerances for piston to cylinder

wall fit to be .002 — .0025 What I think would be a better idea is to buy the std

bore Wiseco’s and bore your 883 cylinders to 1200

spec.

Your current cylinders have been heat cycled. Meaning

that they have «cured». This usually will produce a

better cylinder.

I’d recommned what another lister advised if you don’t

want or have access to a reputable machine shop to do

the boring. Send the cylinders to Wiseco and have them

bore them to fit std size 1200 pistons.

That’s my $.02

Noface

———————————

— Roger Greene <bigbadrogg@home.com> wrote: >>>I am trying to plan my

883/1200

upgrade. I want to keep it simple but strong.<<<<

That’s a GREAT idea — SIMPLE IS GOOD.

>>>New heads, Screaming Eagle / new cylinders / new pistons / HSR42 flatside

carb, SE bolt in cams, SE ignition and SE coil. I figure I should expect about 70-80

hp. My goal is moderately high hp and low to mid range torque, and high reliability without

above average maintenance.<<<

Yes, not getting Thunderstorms because they’re black IS lame, but not as

lame as spending good money for underperforming S/E heads, or needlessly spending

money on the HSR carb when you’re still not sure if it’s necessary. The Crane

ignition idea was also a waste — remember, KEEP IT SIMPLE. Here’s what I would do, if I were you:

1) Heads: The foundation of the upgrade. You’ve got great heads already! Take the 883

heads you have and send them to a REPUTABLE PRO for a port & polish, like

Head-Quarters up in Canada. DO NOT let your local backyard mechanic and his dremel do this,

trust me. Anyway, with a set of HQ 883 heads and matching components, you should be in

the high 80s, possibly 90s HP with good torque to match — for not much more than

you would have spent on the sloppy, cast S/E heads. And the heads stay silver and look

stock!

2)Other components: Use what HQ recommends as far as pistons go, and take

their advice on buying vs. boring cylinders. You can likely stick with the S/E dual-fire

6,800 rpm module and S/E coil too. Cams are up in the air, but I guess the S/E bolt

ins / Andrews N4 would give you what you’re looking for, as would HQ’s own cams. No need

for the Mikuni carb unless you just can’t get the CV to run right, though it IS a

great carb and offers more tuning options. As for reliability, if you correctly build a

high performance engine with quality parts, it will need no more care or maintenance than a

stocker would. Happy shopping!

-MKL ’98 1200C (…94+ reliable, daily driven HP…)

END OF THE FAQ


[i] Make sure to check out the �technical� section at http://www.sporster.org

[ii] There is some controversy as to exactly how much HP a stock 883 makes. I am using the figures of 42 HP and 43 ft/lbs of torque. After completing stage I upgrade these figures would obviously be higher but not much.

Version History:

Version 1.6

Added index

Revamped Intro including some links

Minor updates to Upgrade Path section

Added Heat problems to Reliability Section

Minor wording changes to Cams Section

Added links to Supplier List Section

Added sections on dyno, squish and compression

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