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.

Time- If 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

------------------