What is the weak link in an evo sportster drive train,any of you guys 1/4 mile race your sportsters,the were and tear on an engine and drivetrain must be tremendous:wonderlan ,wounder what breaks first,some thing in the motor or trans or clutch area,what areas would need to be beefed up.:rolleyes:
Thanks,Glen:geek

I've only been on the 1/8, but so far so good. Got over 100 runs on my 01 bike with no problems. Ride it to the track have some fun and ride home. Even running the same oem belt and clutch assy when it was new in 2001. Got 25K miles on her.

I am going to go with a chain conversion one of these days just incase plus I'll be able to change my final gearing to get in the high 7's in the 1/8 next year.

You got to remember these's bike don't make that much HP so there's not as much wear and tear say like on my Suzuki dragbike with 1395cc, delay box, 7 inch slick, launching at 7K shifting around 10-11K. I got about a thousands runs on this bike and have broke a crank, case, ring gear on the clutch basket, bent valves, starter clutch, etc.

When I go racing with the Sporty I'm slowest bike there, even the 600's are faster but that doesn't matter, what counts in consistency and that can get you to the final.

I'd like to build a Sportster only dragbike that would do 100 mph in the 1/8 and be done with it. I don't see many HD's at my track racing besides me and think it would be cool to have something that's different.

Right now my Sporty will do 8.40's in the 1/8 at 80-81mph all day long and the only problem I have is the red light. It's alittle harder to cut a good light once you cross over to the darkside and cross back :banadanc

I've raced mine 3 seasons. The first month and a half I broke 4 belts. Everyone says that shouldn't happen but it did with me repeatedly. Changed to a chain and never broke anything else. Did put a new extra plate clutch in after the first season but the original one had a lot of miles on it.
When we tore it down to do the new conversion I sent the tranny off to be back cut and checked out. They suggested I change 2 gears and one fork due to wear.
The bike had, before the conversion: 94.2 hp and 85.8ft/lbs of torque with S&S Super stock heads and HQ cams on a stock 1200 bore(.020 overbore for cleanup)
1/8 mile time 7.55 to 7.72 between 90 and 92 mph. I weigh 225 with leather jacket and helmet.
The thing that gets the most wear, of course, the rear tire.:smoke
Hope that answers you question.
Dana
P.S. This an '01 with over 61,000 miles.

6.2 ish 1/8th
at this point there are some things that show up. Mid sevens in the 1/8th and 11 and twelves in the 1/4 and these motors are tough enough. But once you are into the 10's and even the nines things are pushed beyond the envelope. So stay away from the 10's and you will remain healthy and wealthy. My motr ran all year long in the elevens...and even got a full season in the mid tens.

6.2 ish 1/8th


Oh now you're just being a smart a$$ Kerry. I'm a full second behind that and I thought I was doing alright. Even at 8000' (7.23 1/8th)
When you get sick of your engine and want to give it away, let me know. I'll be quite happy to pay for shipping and if you're undecided about giving away the complete engine, i'll offer the same deal for those new heads you have. :smoke :smoke

You are doing alright friend. Stay away fromthe sixes ,thats where stuff starts breaking.

IOP the belt will be the weakest link. Keep an eye on the rear pulley & belt for wear. The clutch & tranny are rock solid bellow 100 HP. http://i101.photobucket.com/albums/m54/cwissler/th_wheelie.jpg (http://s101.photobucket.com/albums/m54/cwissler/?action=view&current=wheelie.flv)

The clutch & tranny are rock solid bellow 100 HP.
No problems above 100 so far. Just broke two belts on the strip with hard launches.

No problems above 100 so far. Just broke two belts on the strip with hard launches.
I hope I can say that some day. Man you must have a rocket!

I hope I can say that some day. Man you must have a rocket!
NRHS buddy. they rock. Although I do feel i need more right now.:tour

next comes the bottle. I have to tell you if we got together I would let you ride either of my bottle bikes...it is the nicest feeling when the bottle comes on hard....highly addictive. At the track though I have it come on softly and ramp up pregressively to avoid tire spin like this run...it just kept spinning and pushing to the center line . Click on the image.
http://img.photobucket.com/albums/v700/Narley/Harley%20racing/th_dragraceslip005.jpg (http://smg.photobucket.com/albums/v700/Narley/Harley%20racing/?action=view&current=dragraceslip005.flv)

So what's involved that? I assume dropping the CR and differnt port work. Maybe even smaller valves??
Damn, it would be nice if i could keep the heads i've got. They're expensive to replace.
That run was awesome BTW. You were fighting that thing 3/4 of the run. Bet you puckered just a little. :p

A little pee came out , But I had heard its best to stay in it so I think i kept it pinned. No cr change needed less you are over 12-1. Just get the edelbrock kit and start with small jets. Take out a little timing and or check to see if your ignition has a retard trigger. Nitrous is really simple...we can talk more, buts it pacific coast bed time.

You're killing me. No mods from where i'm at?? So which kit did you get? You got a part number?

Another thing Kerry. Why did you go with Edelbrock as opposed to the other kits that are available?

The Edelbrock kit is a very simple kit to install as it does not require the intake to be drilled, etc. I am running an twin fogger nozzle setup. The parts are made by Holley (NOS Brand). I am using an Edelbrock side cover (because it hid the solenoids and fuel pump nicely) and and Edelbrock bottle because it is a little bigger than the NOS brand bottle. I have a complete "how to" in the carb section, just do a search for Nitrous and you'll find it. I am not running a nitrous retarding ignition and have not had any problems, but I am only at 10:1 compression.

sorry for the delay but I am away for a few eeks...we will talk lots soon.

we sheared a wrist pin and bent a rod in our bike, we run mid tens. i personally think that the rods are the weakest link in the sportster. ive known several people bend a rod runing compression ratios around 13to1 and higher

Have got around 500 passes on mine and over 80,000klms..

It has spent many hours going around the race track at full noise as well..


DId a belt at 40,000 ... stripped bottom end and resized rods at 30,000... then threw those rods away at 82,000...

Everything else holds up fine...


That was doin high 11's @ 113 and mid 7's on the 1'8th


All in full street, daily transport trim on pump fuel...

since we are on the subject,how much horse power roughly are we talking to get in the mid 12`s.

Correct me if I am wrong someone please, because I am new at this, bu in response to the question above, it would take around 80 hp. I am a beginner at this. I don't know what I have for HP, but I think, just by testing last night, I can run 12 flat at 110 and I have maybe 86-88 hp, maybe I am pushing 90-95 with a good two into one and tuning. :dunno Just my thoughts. I weigh 230 with full dress and a helmet.