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2 vs 4 Stroke


fastkid

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I been reading up about pro stock motorcycles last night and seen the they use 1500-1650ish cc 4 cylinder motors (4stroke obviously) and they are putting out around 350 horsepower on gas. Now I'm not sure if this is at the crank or wheels but sill... And they rev up to 15,000. How is this possible? Why can't even little banshees rev this high? And that's crazy power for the displacement, even on gas. I'm not sure what dyno numbers the 4 cylinder banshees put down but they couldn't have been much more then that, and that's on alcohol. So what am I missing here. Thought two strokes were unbeatable vs 4 stroke with the same displacement. Discuss

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They don't make a production 2-stroke streetbike.

So there is no class to race them against 4-strokes.

A basic YFZ450 can out rev a Banshee. How? Well on a Banshee the piston is very tall and has mass.

The 4-stroke piston looks like somebody mounted rings on a QUARTER and then fitted a wristpin to the bottom.

Raptor 700 = Banshee 350

350×2=700 so you see a 2-stroke makes the same power with 1/2 the cc's.

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I'm no expert but I think they can rev higher because of the short stroke. It allows more piston speed which is what limits the rpms that a engine can turn because oil will not protect a piston above a certain feet per second. I was told that in a diesel engine piston speed is nearly the same as a formula one car. Please correct me if I'm wrong.

 

 

Sent from my iPhone using Tapatalk

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But lets do some math

 

your pro street is making .211 hp/cc. (350hp / 1655cc)

 

a 4mil cub has a ratio of .238 hp/cc (100hp / 421cc)

there is a 4mil cub making 200hp, that is a ratio of .475hp/cc, so your shit is way off.

Who mentioned a 200hp 421?... If that was directed towards me, I said 4 cylinder, not 4 mill banshee. As in the 4 cylinder cougar banshee that a few people had that were in the 1600cc range. Hence the reason for the comparison. As for the other math you did that was actually correct, even that is comparable to two stroke numbers. Just didn't get it is all, r&d I guess. Nsr500 made 200+ hp on gas so I guess enough money can get you there.

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