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Old 05-20-2003, 10:17 AM   #41
12er
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Default Re: AMA Superbike rules will prove to be better over WSB.

Even with restrictor plates that suzuki is all over hodgsons @ss... Who'd Ducati blow at WSB?
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Old 05-20-2003, 10:27 AM   #42
Jason523
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Default Somewhat useless write-up

I don't think the test was needed. Seems like MO just is straining super hard to find things to chat about just to keep you other fellas on here from crying about your 11 dollars you spent.



Just kidding........
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Old 05-20-2003, 10:30 AM   #43
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Default Re: '03 Best of the Best Feedback

gixxer 370

kawi 355
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Old 05-20-2003, 10:49 AM   #44
Abe_Froman
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Default Re: Any Chump Can......

Just as any chump can highside (or wash out the front due to driveline lash) a 600 while trying to keep up with the liter bikes out of corners on a public road.



The street is not the place to explore the limits of your bike.
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Old 05-20-2003, 11:14 AM   #45
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Default Re: Johnny.... you missed a great opportunity.

No. I am saying that AMA rules that weigh displacement very heavily, while ignoring other equally salient features like valvetrain configuration, number of cylinders, type of cooling, or type of combustion cycle (two stroke versus four stroke) are at best patently stupid, and at worst a result of graft.



A four stroke should get about twice the displacement as a two stroke, no problem, the math works. Along those same lines, I don't think it would be unreasonable to see a bored out 1200 cc Buell XB9s (air cooled pushrod 45 degree V Twin) racing against 600cc water cooled overhead cam inline fours. I think the math supports it, or something close to it. And maybe a SV-650 (water cooled oversquare OHC 60 degree twin) at closer to 850cc's.



These bikes (600's, SV-650, XB9) are about being quick, light, and maneuverable, not about breaking the sound barrier while handling like a truck. Think of them being classified by the kind of track where they thrive.



People hung up on power versus displacement as their only (or primary) metric for "quality" are only showing their ignorance of physics (IMHO).
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Old 05-20-2003, 11:43 AM   #46
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Default Re: AMA Superbike rules will prove to be better over WSB.

"The 250cc advantage of VTwins" is not some sort of arbitrary "we love VTwins" bonus rule, it is the result of simple physics. Four smaller pistons will *always* be able to make more power then two larger pistions. The math is simple and well known. Just like a two stroke will always make nearly twice the power of a four stroke. It's simple physics.



Ducatti may have been dominating the races with their VTwin, but it was not the extra 250cc's of displacement, it was optimized piston geometry (very oversquare) and the desmo valvetrain. Add that same desmo valvtrain to an inline four, watch it get less valve float at higher redlines, and watch it walk away from a non-desmo 4. If you don't believe me, check the lap times of the new desmo V fours. Ducatti was winning because it had a more sophisticated valve train.



If the AMA wanted to make a displacement adjustment for the physics advantages gained by a desmo valvetrain, I have no beef. But they effectively nuked every V-Twin.



The RC51 was doing well because honda dumped buckets of money into it. And watch it get eaten alive by the new Honda V5's of equal or less displacement.



You are right, nobody makes two strokes for the (U.S.) mass market, they suck as street bikes. Power is peaky, maintenance is high, pollution is bad. So you are saying that the race bikes should mirror what makes a good streetbike, right? Then we agree! The bikes that race in these types of classes should reflect the bikes that are being ridden on the street.



But then you seem to be asserting that the only valid sport oriented streetbike engine configuration is a watercooled overhead cam inline four!?!? That is just plain stupid. For the streetbike type classes we are talking about, the rules should be based on physics, and should exist to try and equalize all valid and reasonable commercial offerings.



As written, the rules effectively mandate a liquid cooled, four (or more) cylinder, desmo or overhead cam engine. Any other configuration is at a HUGE disadvantage.



And I reiterate. Claiming that the only measure of "quality" of a sportbike engine is simply power produced versus displacement simply demonstrates ignorance. I can think of a half dozen or so more significant metrics off the top of my head. That measure of "quality" would mean a two stroke would be the ultimate sportbike street engine, which is obviously false.



And if you want racing classes to be built around "most popular streetbikes", then how many pushrod twins got sold over the last few decades versus inline four OHC's

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Old 05-20-2003, 11:54 AM   #47
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Default Re: AMA Superbike rules will prove to be better over WSB.

Missed one



Tweaked but still *very* streetable Buell Firebolts (bumped up to 1200 cc's) are being built today by Nallin Racing in Colorado. Dyno's have been posted nosing right around 110 horses, with a torque curve that is to die for. With that setup they won't be dominating anything, but they could be competitive on some tracks, and would make for some entertaining races, and it would be nice to see at least one American Motorcycle racing in that American Motorcycle Associating Professional Racing series.



I don't know what people are doing to SV-650's, but I would be suprised if it were not possible to massage that into a competitive platform as well. That would be another great bike to see mixing it up.



Don't give it advantages the physics don't warrant, but dont pick some stupid rule like "displacement is the only valid metric" and base an entire "professional" series around that. Is the AMAPR that stupid? If that's the best they can do, what good are they?



Even the stock XB, which is way down on power, was going toe to toe with an F4i on tight and technical tracks. You know, the kind of tracks that the inline four 600's like to race on...



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Old 05-20-2003, 11:57 AM   #48
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Default Peak HP vs Torque (Ftlbs, Newton Meters) be clear what you are talking about

Actually you should clarify by power do you mean horsepower or torque. You assertion that multliple cyclinder makes more power is true if you are talking about peak horsepower. If you are talking about torque the 2 cylinder bikes have an advantage at low rpm levels. At higher rpm levels the advantage goes away (given the same displacement). As an engineer I think it wrong to make a blanket statement that " Four smaller pistons will *always* be able to make more power then two larger pistions. " Are you talking abut Peak HP or Torque (which arguably wins races at least that is what Ducati thinks) ????
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Old 05-20-2003, 12:05 PM   #49
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Default Who won last years WSB?

Colin Edwards with a Honda RC51 so much for Desmo valves. I think you overstated that point.
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Old 05-20-2003, 12:05 PM   #50
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Default Re:Correction

<blockquote>Four smaller pistons will *always* be able to make more power then two larger pistions.</blockquote>



You should add: "at the same displacement."



The rules were in place so that the amount of air that an engine can pump per unit time would be close to equal. 750cc Four vs. 1000cc Twin = about the same pumping speed given the differential between maximum piston speeds. As reepicheep sez, it's not favoritism, it's physics.



One other reason for the advantage of the twin is not only the midrange power availablity but also the traction advantage gained by the power pulses of a V-Twin over an I-4.



"The twins also put the power on the ground differently than a four. With most fours, one piston is usually on its power stroke at any given time, so a four will feel smoother but it will also spin the tire easier for that same reason. With a twin, one cylinder fires then the other so you have the effect of turning on the motor then turning it off. The tire will actually start to spin then be off of its power stroke so it will regain traction. This pulsing effect gives the twin an advantage in the traction department. In the Grand Prix two-stroke class a couple of manufacturers produced what was known as a "Big Bang" engine, where all of the cylinders would fire almost simultaneously to give this same traction advantage."

-http://www.boldbikes.com/techie/no99tech.html
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