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Buell Forum » Knowledge Vault (tech, parts, apparel, & accessories topics) » Engine » Big Mechanicals: Head, Cyl, Piston, Rod, Crank, Flywheel, Cases, Bearings » Archive through July 16, 2008 » Buell vs. Sportster engine difference « Previous Next »

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Buell_bert
Posted on Tuesday, March 18, 2008 - 01:25 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

What if any is the difference between a say 2000 Buell and Sportster engine. HP, torque, internal parts. I've heard the Buell engine puts out a bit more. Thanks for any feedback.
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Mikej
Posted on Tuesday, March 18, 2008 - 08:39 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

There were both carb'd and fi'd Buell engines in 2000, not sure about the XL. Cams were different between the Buell model V-Twins which made a bit of difference in the hp/tq curves. Exhaust and air cleaner systems also made a difference between the Buell and XL bikes. I don't have the hp/tq comparisons handy, maybe someone else will.
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Sportyeric
Posted on Wednesday, March 19, 2008 - 10:15 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The Sportster used the same head design from 19869(?) on, until the rubber-mounts came out a couple of years ago. Except the Sport model, which used a dual-plugged version of the S1 Lightning head.
The Sportster uses the same cams as an M2.
A lot of the power difference is from the intake and exhaust restrictions that are a result of styling choices combined with noise reduction.
Heavier flywheels, too
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Rick_a
Posted on Friday, March 21, 2008 - 12:18 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

2000 Buells had Thunderstorm heads and pistons, XL1200's had the standard squishless hemi chamber used since I believe 1988. The Buell used a bolt-in performance cam in all models but the M2. Buell flywheels were much lighter (I believe around 12 lbs). The compression ratio on Buells was to 10:1 VS 9:1 on XL's. The Buell rev limiter kicks in at 6800 rpm, a Sportster signs off at 6500.

Newer Sportsters ('04 up) use XB heads (on 1200's only) and higher compression (9.8:1), but are still down on power due to styling restraints (small, restrictive aircleaner, stylized dual exhaust).

The Buell's intake and exhaust alone (larger airbox, header, large volume muffler) accounted for about 25% more power.

Buells also got a revised 2nd gear ratio as well that year.

I think most stock Sporty's at that time were around 55 RWHP and 60 ft-lbs and Buells were around 85 HP and 75 ft-lbs.

The S2 was the last Buell to use stock Sportster internals.


(Message edited by Rick_A on March 21, 2008)
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Medic352
Posted on Sunday, April 27, 2008 - 04:18 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

From 2002 HD Sportster Service manual:

883 rated 57 HP @ 6000 RPM
1200 66 HP @ 5200 RPM
1200S Sport 69 HP @ 5500 RPM

From 1999/2000 Buell Lightning Service Manual:

2000 X-1 101 HP @ 6200 RPM
1995-96 S-2 76 HP @ 5200 RPM
1997-98 M-2 83 HP @ 5800 RPM

To my knowledge, the XB 12's were to be 104 HP. My '04 XB12R, with a stock muffler, stock ECM and K&N air filter made 94 HP to the rear wheel. On the same day my old '03 XB9S made 80 HP to the rear wheel with the Buell race ECM, air filter(K&N) and race muffler. The 2000 1200S Sport I had made 69 & 70 HP on several dyno pulls the only change was from a V&H SSR2 system to a Super Trapp.

Buell's use the Screamin' Eagle 'Bolt-in' camshafts (except for th M-2), same with the lightened flywheels (also not in the M-2).
In my experience and part numbers the S-1 Lightning head is the same as the Thunderstorm head, but they went from a flat-top piston to a dome.

The heavier flywheel in the M-2 and XL's will 'feel' torquey-er. Buell's also gain from having an excellent exhaust system from the performance stand point, where as XL's get stuck with drag pipes and street sweepers, more for looks than go.

Buells also get to operate at higher RPM's thanks to rubber mounts, Sportsters were solid mount until 2003. As for HD using Buell hot rod stuff, look no further than the Sportster Nightster with XB heads, pistons, and cams(and much more HP).

As for all the dyno data, in the summer time, there is a shop here in Tulsa that had a summer long dyno shoot out, it had several classes like 1200cc Buell/Sportster, Imports, 80 inch V-2, Twin cam, etc. It included Saturday night dyno pulls(two pulls for $20), with beer and sometimes a band, and usually lot of girls and tons of bikes of all kinds.
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Djkaplan
Posted on Monday, April 28, 2008 - 01:49 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

2000-2002 M2's have the same lightened crank as the 2000-2002 X1 and S3.
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Blake
Posted on Monday, April 28, 2008 - 06:42 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Further clarifications to the above:

Thunderstorm heads are quite different from their predecessor Lightning heads.

Nothing about a heavier flywheel will make an engine feel torquey-er. The opposite is true since the heavier flywheel absorbs/stores more energy during acceleration.
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Rick_a
Posted on Saturday, May 10, 2008 - 09:40 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Lightning heads 16703-96YA, 16704-96YA
Thunderstorm heads 16797-98Y, 16798-98Y
I believe the casting numbers on the heads are the same, but they are definitely very different otherwise.

The Blast! head is basically the same as a Lightning head with a Thunderstorm piston.

It's the milder cam that makes XL's and M2's feel torquier.

'03-prior Sportsters were limited in their RPM only by application. 6800-8000 RPM modules have always been available. The 04+ Sportsters still use the same rev limit despite the rubber mounts.

The XB-style heads have been used on 1200 XL's since 2004, and the cams and pistons are not XB spec (pistons are flat-tops; hence the 9.7:1 C.R., the cams have much less lift and duration).
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Bombardier
Posted on Friday, May 16, 2008 - 04:30 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Blake,

The enduro and motorcross fraternity have, in recent times,been installing larger flywheels to their engines as they have realised what the manufacturers of Harley/Buell have known for many years that torque is the key.

A larger flywheel though needing more energy to get it to a certain rpm will resist attempts to reduce its rpm due to the energy it now posseses.(Objects in motion tend to stay in motion.)

I believe that Medic is correct in what he states about a larger flywheel motor being torquier.
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Pammy
Posted on Friday, May 16, 2008 - 05:05 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

It's called momentum.
A heavier flywheel will make more low RPM torque. It will also make the engine seem smoother.
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Rick_a
Posted on Saturday, May 17, 2008 - 11:28 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Heavy flywheels in offroad racing is not to increase torque per se but to improve tractability on loose terrain.
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Djkaplan
Posted on Tuesday, May 20, 2008 - 12:53 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I agree with the tractability issue with a heavier flywheel. If a heavier flywheel is producing more torque on a dyno, it's not the extra flywheel mass that's creating it, it's probably a result of the damping effect the mass has on crankshaft motion.

A heavier flywheel has actually been shown to produce more peak horsepower on some engines as well. The larger mass works as a damper (for valvespring harmonics too) and helps keep valves in contact with cam lobes at a higher rpm.

Kevin Cameron touched on the subject just recently in his CycleWorld column. He never mentioned specifically what engine though...
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Bombardier
Posted on Thursday, May 22, 2008 - 08:50 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

How would a larger flywheel affect valvespring harmonics Dj?
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Jeffreyh
Posted on Friday, May 23, 2008 - 10:58 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

"A heavier flywheel will make more low RPM torque."

Sorry Pammy that's wrong. If that was true we'd all have 500lb flywheels in our motors.

Torque comes from cylinder pressure and bore and stroke not from more load. All a heavier flywheel does is store more of the energy from the motor.

In fact, on a Dyno Jet type dyno (inertia type) heavier flywheels will show LESS torque because the motor has to not only accelerate the drum but the flywheels as well. Hence the acceleration is slower and acceleration rate is how the Dyno Jet makes it's measurement.

Torque is what causes acceleration. More flywheel weight means less torque available to accelerate the bike.
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Panic
Posted on Sunday, June 22, 2008 - 01:25 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Re: "Nothing about a heavier flywheel will make an engine feel torquey-er. The opposite is true since the heavier flywheel absorbs/stores more energy during acceleration."

True - but a heavier wheel will allow more aggressive clutch operation at low speed without stalling, pull away with less throttle opening, run at walking speed without chain snatch.
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Bombardier
Posted on Monday, June 23, 2008 - 06:52 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Torque is a twisting force.

I would rather try to stop a bicycle wheel from turning at 100rpm than a motorcycle wheel at the same rpm.
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Reepicheep
Posted on Monday, June 23, 2008 - 09:38 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I'm with Bombadier... a flywheel is an energy storage device, so it will absolutely give transient (not steady state) torque boosts.

So when you dump the clutch at moderate revs and light throttle, a bike with a light flywheel will lurch and stall, and a bike with a heavy flywheel will wheelie and loop.

The difference will feel significant to the average street rider, and is consistent with the normal misuse of the term "torque" in the motorcycling community.

Steady state though, more flywheel
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Djkaplan
Posted on Monday, June 23, 2008 - 12:40 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

How would a larger flywheel affect valvespring harmonics Dj?

By damping the variations in crank rotation... no matter how cams are driven or where they are, they are driven off the crank rotation. Smoother crank rotation = smoother cam rotation.

I suggest you read the article if you can find it. Any explanation I could give would be second hand from the article... it's better to get clarification directly from the source.
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Petebueller
Posted on Tuesday, June 24, 2008 - 07:07 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

This thread has explained to me why the '07 XB12 holds a wheel stand through gear changes better than an '08, even though the '08 has seemingly more on tap.
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