Hi folks,

I currently have this setup:

2003 883 XLCustom
170-45 jets, stock needle, mixture screw at 2 turns
Cycle Shacks slash cut exhausts (slip-ons)
S-E air cleaner
S-E coil
S-E Spark plugs
S-E Wiring

It crossed my mind at several occasions and I'll probably do it soon. I would like to get the S-E piston kit (10:1) but keep my 883 heads stock. Other than reboring my cylinders and getting head gaskets, what else do I need ? Do I need to get a 180 jet an adjust the timing on the bike ? Anyone has the HD pistons ? Do you like them ?

Also, is someone would be kind enough to mark down the HD required part numbers for gaskets and other parts if necessary.

Thanks a lot !

Since I'm in the middle of the exact same conversion on my 02 custom, I'll just mention that HD gaskets suck (even THEY will tell you that). I'm using James gaskets...

Worry about the jetting AFTER the conversion (one step at a time), and someone else will certainly chime in here re: timing....

Hi folks,

I currently have this setup:

2003 883 XLCustom
170-45 jets, stock needle, mixture screw at 2 turns
Cycle Shacks slash cut exhausts (slip-ons)
S-E air cleaner
S-E coil
S-E Spark plugs
S-E Wiring

It crossed my mind at several occasions and I'll probably do it soon. I would like to get the S-E piston kit (10:1) but keep my 883 heads stock. Other than reboring my cylinders and getting head gaskets, what else do I need ? Do I need to get a 180 jet an adjust the timing on the bike ? Anyone has the HD pistons ? Do you like them ?

Also, is someone would be kind enough to mark down the HD required part numbers for gaskets and other parts if necessary.

Thanks a lot !



Lex..The best way to go. Bore the cyls, and use Wiseco pistons. I did it that way and the bike kicked factory 1200's asses.
Sure I'm prejudiced, but I got the idea from the 5 Harley Mags I have gotten each month for the last 8 yrs.
Every thing I ever read said that Wiseco's were the best. Their only drawback is that they are slightly more expensive the Harleys. BUT, they are forged which means stronger.

I would like to get the S-E piston kit (10:1) but keep my 883 heads stock. Other than reboring my cylinders and getting head gaskets, what else do I need ?

Thanks a lot !

What Maddog said about Wiscos. Also, get the cometic gaskets. They work great and are only .030 thick.

As far as your heads, try to at least get the 1200 valves and a valve job. You'll thank yourself after.

I'll just mention that HD gaskets suck (even THEY will tell you that).
Why do they suck?

Lex
I don't know a lot about this conversion stuff - but I know that when my warranty expires I'm going to contact this place regarding the conversion. They are a reputable vendor on this site and lots of people on here have dealt with them and given A+ reviews. Here's the link - http://www.nallinracing.com/ekit8831200.shtml

Why do they suck?


Paper...

Aftermarkets are SUGGESTED even by honest dealers when you start doing performance work.

The new HD gaskets are made by Cometic and are metal.... new HD's/Cometics or James are the way to go..

For street use on a basic 83-1200.... boreing your cylinders by a REPUTABLE engine reconditioning company that has torque plates is a good way to go.

HD pistons or KB's are a better way to go than the Wisecos as they are a Hypereutectic cast material and expand less... making them better for normal street use..

Nothing wrong with Wiseco's ... we tend to use them over here only because the importer has a REALLY good deal with Wiseco and they are the cheapest...


Nothing wrong with dished pistons and keep your 883 valves for bottom to mid range use. Get your valves and seats re-cut tho... so they're fresh..


Jetting and timing are tuning issues and are adjusted AFTER as or if NEEDED

The new HD gaskets are made by Cometic and are metal.... new HD's/Cometics or James are the way to go..

Sorry Stevo, I stand corrected.

Sorry Stevo, I stand corrected.


The old paper ones were crap compared to the new metal ones......

I never had any leaks from any that I did tho....although mine had then leak within the first month or so after I bought it, then I never had a prob after I changed 'em and that was on paper ones for years......with 518 tho

As far as your heads, try to at least get the 1200 valves and a valve job. You'll thank yourself after.


Amen to that Brother. As far as I'm concerned , a conversion is only half done without them.

Nothing wrong with dished pistons and keep your 883 valves for bottom to mid range use.

I'm with Stevo on this one....no racing, no need for new valves....especially with only 6,000 on the bike to begin with.

Correct me if I'm wrong, but I understand there are distinct advantages to keeping 883 valves....

My .02

The new HD gaskets are made by Cometic and are metal.... new HD's/Cometics or James are the way to go..
How new is "new"? The reason I ask is because I bought a complete engine gasket kit when I did my conversion over a year ago, and I've had no problems at all with any types of leaks. And I've never heard the HD gaskets were crap. I've heard they would do the job, but some other brands like James' were better.

I don't think the stock H-D gaskets are any worse than lets say Cometics.

The reason I say this is because I bought complete set of Cometic gaskets when I pulled my engine apart for the heads, cams, and piston change a couple of weeks ago.

Just a couple of differences between Cometic and H-D for the 04.

The lower rocker box gaskets are metal on both Cometic and H-D, and are almost identical.

The upper rocker box gaskets are rubber and look identical on both Cometic and H-D.

The base gaskets are different. Single layer metal on Cometic and a regular paper type on the H-D (but never had an H-D base gasket leak on my 04)

Cometic uses a 3 layer metal MLS head gasket (avail in either .030" or .040" thickness). The stock H-D head gasket is graphite. I think there both good. Seems like some folks like a graphite head gasket and some think the metal MLS head gaskets are better for various reasons.

Don't know anything about James gaskets.

Correct me if I'm wrong, but I understand there are distinct advantages to keeping 883 valves....

My .02
If there is I have NO idea what it may be. I put 1200 valves in mine with the convo and performance was radicallyincreased across the spectrum. High mid and low range. I don't know what possible advantage you could get by starving 1200 cylinders with 883 valves.


In fact, let's cut through the bullshit shall we? I learned a lot over the course of having my conversion done and there are a few reasons people will tell you you don't need valves
1. They do not have the machine shop capacaty or an experienced machinist to do the the work in house. I know this because as I was going to several different places and those without a machine shop kept telling me I didn't need to do it.
2. They simply want to take your money with minimum effort. It only cost me an extra $200.00 for the valves and they did it in house.
3. NEVER go to a Dealer to have it done. They simply want your money and don't give a shit how your bike runs afterward.
If I stepped on any toes, I apologize. But if your going to sink a load of cash in an engine upgrade, do yourself a favor and do the WHOLE job. You won't regret it.

4. they're just too damned cheap or can't come up with the money for it. (probably reason #1 actually)

I'm with Stevo on this one....no racing, no need for new valves....especially with only 6,000 on the bike to begin with.

Correct me if I'm wrong, but I understand there are distinct advantages to keeping 883 valves....

My .02

However, if he WANTED to add add cams or something else LATER, he would already have the valves and not need to remove his heads again. 1200 valves with a good valve job would be enough if he wanted to do a few more upgrades later. Just a time and money saver to do them once instead of gaskets and stuff later.

I doesn't matter who you are, you will never have enough.

Exactly, I plan on cams later, and the head work is already set up for them.

If there is I have NO idea what it may be. I put 1200 valves in mine with the convo and performance was radicallyincreased across the spectrum. High mid and low range. I don't know what possible advantage you could get by starving 1200 cylinders with 883 valves.


In fact, let's cut through the bullshit shall we? I learned....<snip>

Ummm....just enough to be dangerous?

If there is bullshit to cut through, I don't know about it.....I'm not even qualified to tell you why its perfectly fine to keep your 883 valves, nor did I present it as fact, but merely mentioned it as fodder for discussion.

I happen to have much respect for the person who I got this information from...I have no reason to doubt it. AND I do my own wrenching....all of it.

You make an excellent point about the cams, etc., save for the fact that they are in the lower end, and you would be disassembling the top end to accomplish those tasks....

Now, having said that, who in their right mind would do MORE work without inspecting what they'd done already? (Depending, of course on the mileage between those two jobs).......thereby making the savings in time a non-issue IMHO.

I would ask if you measured performance before and after 1200 valves alone???

OK a few points here... no I havn't just talked to a couple of guys and done one conversion and seen the light...

I am a qualified tradesman that has been in this field for MANY years....I've built, machined and tuned hundreds of different engines over the years.
I have my own workshop that is nothing more than my own toy shop because I play with this stuff for fun........I read engineering papers for relaxation... (yeah I know I'm strange ;) )

With any engine it is nothing more than a hot air pump (although I see more hot air from some "experts")

There is many forces involved in where and how much power it makes...

If your 883 valves will feed your engine comfortably to 6000 rpm and you go to 1200 then they are still going to feed it well to around 4500, it will start to slow down in power delivery from here BUT it doesn't just fall on it's head it just gives a soft rev limiter.

The optimum port/valve/carby/exhaust size is the smallest one that will feed the rpm range you want...as keeping it small will keep the gas speed up and give better cylinder fill and fuel homogenisation thru the rev range..

Where do you want the power????? top gear roll on to overtake so ya don't have to drop a gear??????
That's around 2500 rpm....
How often or haw far do ya go up the rev range????
5000+ rpm once a month just to blow the cobwebs out????

Then why waste money building an engine to run from 3000 - 6500?????

For street use if you dan't intend racing and just want more for every day use there is NOTHING WRONG with going dished pistons and keeping the 883 valves..

If you intend racing and/or going bigger cams then I would recomend a different path.

I am loathe to recomend going to 1200 valves unless it's done by a shop that knows what they are doing as the ports need to be blended in to get the benefit out of it...If the seats are just cut to suit and 1200 valves plonked in ya not gainin much other than braggin rites to those that can't get out of your way at the pub.

Having said that if ya gonna keep your 883 valves blending the back of the seats into the port to remove the steps will reap large rewards and can be done by most people that are capable of doing the rebuild themselves.......


What is right for one person/engine/$$$ combo may not be ideal for another and trying to force your particular choice on everyone else as it being the "only" one doesn't give one much credibility.....this is where what I was talking about in the off topic area manifests itself in other areas.

If the seats are just cut to suit and 1200 valves plonked in ya not gainin much other than braggin rites to those that can't get out of your way at the pub.


It is absolutely amazing how often it's done like this. We see about everything come through the shop sooner or later, and sometimes it seems as though everyone who's ever installed conversion valves just cuts the seats and throws them in. Total waste of time and money, you're better off to leave your stock valves in.

The seat i.d., the blending job, and the valve job are all critical to the final result. This cannot be overstated. If all you've done is made the seat flare out in a cone shape from the base to the 45, you haven't done a damn thing to help the heads. Might've hurt them.

Hmmmm....seems there are a few more questions in line for you, Desertfox...

What say you?

;)

What Maddog said about Wiscos. Also, get the cometic gaskets. They work great and are only .030 thick.

As far as your heads, try to at least get the 1200 valves and a valve job. You'll thank yourself after.


Lex...No disrespect meant to Stevo, but there are many different opinions as to whats the best way to go. Stevo has his based on his experience.
But many well known Harley engine builders prefer the Wiseco's,like Joe MInton, Donny Peterson, and Buzz Buzzelli. They don't even mention piston expansion so they must not feel it is an issue.
They DO say that the Wiseco's are forged which makes them stronger than the Harley's cast pistons. Stevo says the Wiseco's are cheaper in OZ.
But here in America Wiseco's are more expensive.
What Barry say's about Headwork is spot on. But it's not necessary right away if money is tight. Do the Wiseco conv. (it will have the biggest power punch), and the heads down the line.
I did my Conv. at 4,400 mi. and the heads at 23,000 mi.

Stevo, Aswracing

You've sure Open my eyes on the valve question!!! :yikes

I'm getting ready to do the 1200 conversion myself and wondered about the heads?? But, I guess I'll leave them alone right now and see how it runs and if I want more, then I'll think about head work!!! BTW, I have a '03 883...

Thanks to Both of you for clearing up thing..

im interested in following thred by aswracing

http://xlforum.net/forums/showthread.php?t=2186

the process is just about spot on with the progress i'd take
one thing at a time as the budget can afford it.

cheers
crackers

Great Thread! Don't know how I missed it....

Thanx!

SportsterSpive ...

Just my opinion, but your Sporty is what the Sportster is all about .... Clean, fast, no-nonsense, and lots of power ....

Great dyno graph!

http://www.offroadrangers.com/sean/bike/bassbike2med.jpg

If there is I have NO idea what it may be. I put 1200 valves in mine with the convo and performance was radicallyincreased across the spectrum. High mid and low range. I don't know what possible advantage you could get by starving 1200 cylinders with 883 valves.


In fact, let's cut through the bullshit shall we? I learned a lot over the course of having my conversion done and there are a few reasons people will tell you you don't need valves
1. They do not have the machine shop capacaty or an experienced machinist to do the the work in house. I know this because as I was going to several different places and those without a machine shop kept telling me I didn't need to do it.
2. They simply want to take your money with minimum effort. It only cost me an extra $200.00 for the valves and they did it in house.
3. NEVER go to a Dealer to have it done. They simply want your money and don't give a shit how your bike runs afterward.
If I stepped on any toes, I apologize. But if your going to sink a load of cash in an engine upgrade, do yourself a favor and do the WHOLE job. You won't regret it.

4. they're just too damned cheap or can't come up with the money for it. (probably reason #1 actually)


IMHO Desertfox, having done conv. and heads at the same time, can't know how each feels when done separately. I can explain it.
JUST the 1200 Wiseco conv. on my bike resulted in a 50 % incr. in HP and a 65 % incr. in TQ. The 883 heads had excellent velocity and made the low end power so beastly that factory 1200's ate my smoke. All this for $ 650 out the door is one of the greatest bang for the buck deals you'll ever get. If you are just gonna run on the street, 4 pole's at a time, this is the deal for you. I was happy for 6 yrs like this.
But then, a few yrs down the road, the curiousity hits you...what would a cam and head work be like ?
I didn't do them together because it was all I could do to afford the piston conversion.
My head work and cams should give me a 25 % bump in HP and a little less incr. in TQ. for $1500.
Less of an incr for more money.. But that how it works.
Barry1967 got himself some J.E.T. Heads that specialize in TQ. He spent his money on the low end. The theory there is that the jump his TQ gives him will get him so far ahead that the guys with the HP set ups won't have enough time to wind out their motors to get that HP. And guess what.. on the street, light to light, he'll kill'em. They'll need a full quarter mile to pass him.
Desertfox is right...If you got the dough, do both. If you don't, go at it one at a time.

My 92 runs just under 3000 at 55 now i did the t-storm and put the buell light weight flywheels in now that is perfect because that is right where my torque curve and hp curve meet and where i make massive power

Lex...No disrespect meant to Stevo, but there are many different opinions as to whats the best way to go. Stevo has his based on his experience.
But many well known Harley engine builders prefer the Wiseco's,like Joe MInton, Donny Peterson, and Buzz Buzzelli. They don't even mention piston expansion so they must not feel it is an issue.
They DO say that the Wiseco's are forged which makes them stronger than the Harley's cast pistons. Stevo says the Wiseco's are cheaper in OZ.
But here in America Wiseco's are more expensive.
What Barry say's about Headwork is spot on. But it's not necessary right away if money is tight. Do the Wiseco conv. (it will have the biggest power punch), and the heads down the line.
I did my Conv. at 4,400 mi. and the heads at 23,000 mi.


A few points here..... Joe and Donny know their stuff... but I was under the impression Buzz was a writer NOT an engine builder...

Strength is relative....it's a waste of many things to use a 1" diameter bolt when a 1/4" one would suffice...

Clearance is not an issue ... it's a fact...

A forged piston runs wider clearance... typicall 0.0025" for a Wiseco forged and 0.0009" for a cast Hyper...fact

A short slipper skirt forged piston will wear more under normal daily use than a full skirt Hypereutectic piston..fact


Here's the KEY
Everything in an engine is about compromise and balance... couple this with how many $$$$$ you have to spend and it becomes more complicated...


I will stand by earlier statements ... for street use on a daily basis a Hypereutectic piston is better suited..

If you wish to run Nitrous then use a forged piston as it's better suited

Anywhere in between ...take ya pick... there's nothing wrong with either...I reuglarly build 883-1200's with Wiseco's (3 in the last month or so) and I've run nitrous on Hypers with no probs.

Which ever way one chooses to go it MUST be done correcty to achieve the MAXIMUM benefit......guess work has no place in engine building (development, yes, but that's educated guesses by knowledgeable people, hopefully :rolleyes: different thing)

It's not about what's right or wrong but the best compromise for YOUR application.

Hmmmm....seems there are a few more questions in line for you, Desertfox...

What say you?

;)
I dunno the whole argument is really getting tiresome. I mean if your going to go through the expense of converting, why are you doing it? To go faster. If your going to have an engine gasping for breath at 1200, 2000 or 4000 rpm, why bother? Just leave it an 883. There is NOTHING wrong with an 883. I mean there are some engineers at H-D too. Guys whose workshop is not a hobby either, who have built thousands of engines, and THEY put 1200 valves in a 1200 motor. I wonder why they go through all the bother?

Just an interesting point on that too.....

HD has increased the capcity of the big twins from shovel on BUT the size of the valves has stayed the same or DECREASED... yes the Twin cam exhaust valve designed to feed a larger engine than the EVO is SMALLER than an EVO one...and both inlet and exhausts are SMALLER on the 1450 Twin Cam than a 1200 shovel made in the late 60's


The 1100cc EVO Sportster engine made in the 80's has larger valves than the 1200 sporty made now.... HD engineers went SMALLER again.....


hhhhhmmmmmmmmmmmm... might be something in that after all then????? ;)

Maybe one should ring up the HD engineers and tell them they're going the wrong way :shhhh

I dunno the whole argument is really getting tiresome.

Interestingly, it never really WAS an argument until you decided to share your strong opinions, which have since been refuted by (or at least challenged with) some interesting facts. As the one who decidedly knows the LEAST about any of this.....a novice trying to make sensible decisions and get the most bang for my buck ( because I DO have a family to support too!), I notice you aren't really able to back up your opinions with any real factual or even comparable empirical evidence.

You mentioned how much more power you had after your conversion WITH 1200 valves, but you have nothing to compare it to. From my observation, it seems to be a reasonably irrefutable fact that the most horsepower gained per dollar is with a "bread and butter" conversion. I have increased my displacement by approx. 26%, resulting in approx. 50% horsepower increase? (This hp % is based on dyno sheets I have seen, ymmv)

I mean if your going to go through the expense of converting, why are you doing it? To go faster..

True, but most of us need to balance what we do to our bikes against the dollars available in the household for our hobby. I will have spent about $600.00 US when I'm done, and will have a 1200 to show for it....not bad...

I'm not a speed freak, nor do I give a crap about a dyno sheet, save for the evidence it shows in other projects as a comparator. I wanted some more power for roll-on and for hill climbing, especially 2-up, which I do a lot of.

Forgive me for saying so, but to say that the argument is getting "tiresome" indicates one of two things:

1. You have no real evidence for your claims.

or

2. You don't want to spend the time to explain your stance other than to use a logic-based argument and expect those of us who don't know better to just accept it as fact.

Some posters have given us some VERY interesting facts and history regarding this very subject. We novices, who depend on the experience and opinions of those who have gone before us, need unbiased information...and those of us who actually have brains would like a little back up....especially in the face of conflicting opinions..

With all due respect...put up or shut up. Certainly don't let facts get in the way of your opinions..

Compromise and balance -- with an eye to the rule book -- I built B and C sports racers for 15 years (built them -- didn't have them built) --Compromise and balance -- the essence of engineering. Its a whole different process than the " "magazine racer" mentality, with arbitrary goals and lack of a big picture view. Bigger is not always better -- the most power you can make is not always going to make you faster. The latest and greatest is not always the best solution. AND MARKETING IS NOT ENGINEERING.

All this stuff can be calculated, y'know.

The port velocity that delivers maximum cylinder fill is a well understood number.

Knowing the airflow requirements of the motor (a function of bore, stroke, & rpm), you can calculate the minimum port cross sectional area that results in the target velocity.

From there, knowing the distance and much taper you want from the minimum pcsa to the valve, you can calculate the ideal valve size. Again, these numbers are well understood.

The execution is far more difficult than the calculations.

Whether or not a valve size increase is helpful has a huge amount to do with how it's done.

I dunno the whole argument is really getting tiresome. I mean if your going to go through the expense of converting, why are you doing it? To go faster. If your going to have an engine gasping for breath at 1200, 2000 or 4000 rpm, why bother? Just leave it an 883. There is NOTHING wrong with an 883. I mean there are some engineers at H-D too. Guys whose workshop is not a hobby either, who have built thousands of engines, and THEY put 1200 valves in a 1200 motor. I wonder why they go through all the bother?


Foxy..883 conv's do not gasp for breath till about 6k rpm's. My 883 stock heads with the Wiseco Dished Pistons gave me 81 lbft of tq @ 3100 rpm.
HP was 60 @ 5500 rpm. It stayed there to 6k.
The ass kicking TQ was due to the smaller ports in the stock 883 heads. Ask Barry1967...His J.E.T. Heads were 1200 heads with material welded IN to make the ports smaller and thereby increase port velocity.
My conv. with the stock heads gave 113" S&S BT's fits for about 3 gears. Then cubes ruled.
I had the heads and cams done because I...

A-Had the money
B-Was curious what is would be like to GAIN power from
5500 to 6500 rpm instead of tailing off.

I might decide after running these N-4 cams for a while that I miss that extreme low end TQ and have a set of N-2's installed.
You may not be aware, but years ago it was a hot rodding trick to put 883 heads on a 1200 motor.
Don't dis the stock heads. For the street they give excellent responce for the RPM range that street riders spend the most time in.

Now I don't profess to know much about this stuff, but from what I understand, in simple terms: when you bore out your cylinders, you increase the distance that the flame front has to travel to get across the piston. Would this not mean that you naturally need bigger valves to handle the job?

Someone mentioned Donny Perterson. I've been to his shop and my buddy has had all the work done on his Softail by them, they do good work. I spoke to them about doing a conversion, just to price things out, but never got into details. They have a machine shop and never said a thing about new valves for a straighforward conversion. BTW, he is one of the premier engine builders in Canada, along with Headquarters.

Now I don't profess to know much about this stuff, but from what I understand, in simple terms: when you bore out your cylinders, you increase the distance that the flame front has to travel to get across the piston. Would this not mean that you naturally need bigger valves to handle the job

You still have the stock 883 combustion chamber. Valves have nothing to do with flame. They just have to closed for the event. Larger jets and accelerator pump are what's needed for the bigger piston to be adequately fueled.

The 883 valves will move the mixture into the cyl FASTER (velocity).
The 1200 valves will move more mixture, BUT NOT AS FAST.
The former improves TORQUE, the latter HORSEPOWER.

With all due respect...put up or shut up. Certainly don't let facts get in the way of your opinions..
Admittedly my evidence is ancdotal, based on my own experience. But so is everyone elses. So my opinions have no more or less weight than anyone elses. It's worth exactly what you paid for it. As far as any kind of "empirical "proof" goes (whatever that may be) I haven't seen any here nor can any be presented here. Lighten up. I didn't mean anything personal.

The former improves TORQUE, the latter HORSEPOWER.

Cylinder fill is the goal, and more cylinder fill always increases torque, regardless of how you accomplish it.

Horsepower in the other hand is torque times rpm, i.e. the combination of how much torque you're making and how fast you're making it. Make more torque at the same rpm and you make more horsepower. Likewise, make more rpm with the same torque and you make more horsepower.

But it gets harder and harder to fill the cylinder as the rpm goes up, because there's less and less time to get it done. Hence the torque wants to drop. When it's dropping faster than the rpm is rising, you're done.

What you're looking for with the port and valve size is the blend of velocity and flow that gives the most cylinder fill. You're right, the ideal dimensions change with rpm, and they grow in size with rpm. But more torque at the rpm of interest is always the goal. That always equates to more horsepower at that rpm, because horsepower is the combination of torque and rpm.

Like I said, the ideal velocity is a well understood quantity and the port & valve sizes that deliver it can be calculated.

The ass kicking TQ was due to the smaller ports in the stock 883 heads. Ask Barry1967...His J.E.T. Heads were 1200 heads with material welded IN to make the ports smaller and thereby increase port velocity.


I might decide after running these N-4 cams for a while that I miss that extreme low end TQ and have a set of N-2's installed.


MADDOG

Alas, I now have 883 "JET" heads. As soon as I pay for them and pick them up. :D I also have N3s, Kind of in between N2s and N4s. I will post my dyno runs after I get it together. It may be a while though. More snow on the way :frownone . I may switch the N3 ex lobes to N2s if the TQ is a bit low. There are reasons for the N3s that I won't go into now but I will be dure to let you know the results.

Originally Posted by Desertfox
I mean if your going to go through the expense of converting, why are you doing it? To go faster..
not nesisarily true. I have not really gone any faster as a 1200 than I did as an 883. Now I get to speed a lot quicker, but over all I can't say that I'm any faster.
Now as to the point of 883vs 1200 size valves, I definantly do not know as much as stevo or arron have forgotten, but the key point as to wich way to go seems to be where do you want your power, 2000-3500 for day to day riding, or 4500 on up. One thing I will add is that after my conversion I have noticed that I like to ride in the upper rpms moor than I used to. So in conclusion if your just looking for 70 hp cruiser and $$ are short do the basic conversion and keep your 883 heads stock. but if your ultimate goal is 90+ hp do your heads initialy so you don't buy 2 sets of pistons.

Some food for thought ...

http://img.photobucket.com/albums/v248/Turbota/Stage1DynoChartb.jpg

This is Turbota's taxes-paid '04 or '05 1200. Correct me if I'm wrong Ron, but this is the stock "W" cams, stock heads, SEII slip-ons, SE air cleaner, right? Also an ignition, but I really doubt that's doing anything for you. Stock carb that's been jetted.

http://www.nrhsperformance.com/pictures/883%20to%201250%20SE%20Air%20Cleaner.gif

Here's my '04 883 in similar state of preparation. It ain't a perfect comparison, but it's the closest configuration I tested it in. It's got a 1250 kit and SE air cleaner. Stock "D" cams, heads are stock, with stock valve sizes. Pipes are stock but later when I went to a CS system it didn't add any bottom end (see sheet in Project '04 Sportster thread). Stock carb but it's been jetted properly.

The 883->1250 motor is 4% bigger and it's got little valves and ports. Recipe for a lot more torque, right?

Keep in mind, too, that when people talk about putting 1200 sized valves in 883 heads, they're really talking about 91-03 1200 sized valves, i.e. 1.715" intake/1.480" exhaust. The new 1200 heads like Turbota's actually have 1.810" intakes and 1.575" exhausts. The new 883 heads still have the little 1.585" intakes and 1.350" exhausts like the 91-03's. So Turbota's valves are actually BIGGER than what we're talking about here with conversion valves. Putting his sized valves into 883 heads is major surgery.

Anyway, how do the charts actually compare down low?

Interesting comparison.....not much in it thru the middle... although I thought the 883's would nose over more up top, 'specially compared to the new 1200 heads...even though the restriction is still noticable

The much larger valves and W cams are giving a bit better cylinder fill, as I would expect..... but certainly not enough to warrant the extra expense for most people....and there in lies the key...

If you consider that a bad tune and dirty air cleaner could cost you up to 10 horses....they're pretty close.


It would be interesting to see how much is gained down low from attention to the missmatch between seat and port...and wether those particular 883 heads are good ones or bad ones....I gather that will be addressed on your Stage 1 set up.

personally I pay most attention to the actual seat area shape and into the bowl, looking at low lift numbers, as I'm of the opinion that if I can start that gas column moving earlier I can get more in, I'm also of the opinion that larger valves help in that area as well as right up top.
Every engine builder tends to have his own particular opinions. ;) :)

IF Ron has a different ignition with a steeper advance curve then that would help in the under 3000 area too...... I'm not familiar with the curves on the new sporties to pass any serious comment tho.

Aaron is right about the combination in my 04 1200 graph. It is a 'taxes paid' 1200 with the stock W cams.

The ignition module was changed to an SE unit with a 7,000 rev limiter just because I was about to install the .551" SE cams after I made this dyno pull. (This dyno pull was to establish baseline before modiftying the motor internally). I figured I would need a higher rev limiter with the new cams I was about to install, so that why the SE ignition module.

BTW, this SE ignition module has the [same] timing curve as the stock module. The only difference is the increased rev limiter and it also reduces timing 5 degrees while at wide open throttle (WOT)

Again ... The graph was for my "Stage 1" taxes paid 04 1200R.

See, there you go Stevo, you're hitting on exactly the point I've been trying to make.

When you talk about a valve size, that's only one piece of the puzzle. It's much too general. Everything you said is exactly correct, there are good heads and bad heads, how the seat blends, the valve job, the taper of the ports, the minimum pcsa, etc, all of those things have a huge effect. So when you just talk about valve size alone, it's too general. If you stick a bigger valve into an 883 head, you may hurt bottom end, or you may help it, depends on where you were and where you went with all these other things. If your 883 heads are typical, and you do the valve size conversion right (i.e. properly size and blend the seat and do a good valve job on it), I submit that you're more likely to help bottom end than hurt it.

Have you looked at many 04-05 1200 or XB heads? They're doing a much better job on the ports and on the seat blending than they've ever done. Every seat overhang I've seen on these things has been in the correct direction, i.e. exhaust seat smaller than the port, intake seat bigger than the port. Hell, some porters do that overhang direction intentionally, for anti-reversion. It's the other direction that kills you, and was very common to find in the older heads.

So your point is exactly right, the variances alone in the heads may be making sense out of this.

aswracing, would those XB or 1200 04-05 heads work on a older (pre 2004) 883.

Yes, assuming you make it into a 1200. You CR would fall through the basement if you stuck'em on over an 883. There are a couple of issues to deal with but it's nothing big. See http://www.nrhsperformance.com/partsoemheads.shtml for the details.

I was into the Pontiac Trans Am and Chevy Camaro crowd for a few years. One of the tricks that I learned while being around them is to use 305 heads on a 350. The reason that they do this is because it keeps the compression up and creates a lot more torque than using the 350 heads. It's a cheap and easy way to create a competitive car for the track but is limited. I never did this myself but the guy that taught me this is a mechanic for GM and had a Camaro that ran low 11's. It wasn't the fastest out there but was fast enough to stay ahead of most while keeping an economical budget.

With my Sportster.. When I did the first conversion, I used flat top pistons and a set of modified heads. Work was done by the previous owner of the heads but what I noticed done to them is the combustion chamber was opened up some and the ports were opened up and polished. Also running stock cams. Never dyno'd it but it has impressed quite a few people.

One of my last races before I broke a piston was against a slightly modified Dyna. Every single time I beat him by quite a few car lengths. After getting back with the group he told me about his friend that also owned a Sportster and did the 883-1200 conversion. He admitted that his friends bike was pretty quick but was no where near as fast as mine. I don't know what was done to his friends 1200 but what it does show is that you can build a Sporty using 883 valves and still have respectable power at the bottom end. I have ended up running a similar setup with the rebuild I'm doing now except for using a S&S carb, single fire ignition system and V&H SS2-R pipe. I think the carb is going to be overkill but will find out more on the dyno this time.

The Keihn carb does a great job with creating power when it's tuned correctly. Something that I think helped a little is that I took it apart and polished the inside of the carb and the slide and matched the intake to the cylinder head and carb. I also used a lighter spring for the vacuum diaphram with jetting and a different needle(don't ask me specs on this.. it's been forever since I did the work). All little things but I think it helped at the end.

Check out the link below.. Pretty interesting info on head porting.
http://www.cycledoctor.com/JohnsonArticles/JET.html

See, there you go Stevo, you're hitting on exactly the point I've been trying to make.


Have you looked at many 04-05 1200 or XB heads? They're doing a much better job on the ports and on the seat blending than they've ever done. Every seat overhang I've seen on these things has been in the correct direction, i.e. exhaust seat smaller than the port, intake seat bigger than the port. Hell, some porters do that overhang direction intentionally, for anti-reversion. It's the other direction that kills you, and was very common to find in the older heads.

So your point is exactly right, the variances alone in the heads may be making sense out of this.


I havn't seen any new style heads yet.... there a few Buell guys pesterin me but I've got a bit on my plate at the moment and I don't want to start doin any real performance stuff untill I've got my bench made and have tried a few things on some sets of heads I have here on my sporty...

I noticed an improvement in the core placings on newer castings.... I did a set of early 90's 1200 heads the other day and there was a fair bit of work involved just getting the steps out and port matching....
Most of the work I'm doin these days is just based on years of experiance and tryin to not get too carried away as most customers here don't use it far enuff up the rev range for the port to become the restriction....

Mind you quite a few of the guys I've done mild improvement work on are regularly at me to go further :D unfortunately I detest mistakes and I'm not going into port reshaping untill the bench is made. I don't have the time to try something and then go and test it at the drag strip each time like I did on mine last time, and will be doin this time too....time cards don't tell lies.. but I need the bench to measure it so I can replicate it and do it in a day instead of 2 weeks :rolleyes: