yes, the rules were written that way, but a long time ago when the 2 strokes began dominating. Hell, you could have a 540 cc 4-stroke in the 250 class up til just a few years ago. When the 125 class rules were written, nobody was worried about the hottest bike out there, an XR250. And up til the YZ250F, the most technologically advanced 4 stroke 250 was the KLX, but it was still a pig.mtk said:. . . Rules that were written to try and make the aforementioned turds competitive. The rules give an unfair advantage to the four-strokes, which is why the 450s all make more power than the 250s. It's even worse in the 125 class. But peak power is only a small part of it. Not only do they make more power, but they have a larger spread of power, making them easier to ride.
XRpredator said:and I think we've also seen that guys who ride 2 strokes are whiny crybabies. :nener:
mtk said:The 2-1 displacement relationship ignores the increased thermodynamic efficiency the four-strokes get from their higher compression ratios.
noddy barber said:The General Feeling Is That Although 4strokes Are Easier To Ride,:think:
noddy barber said:The General Feeling Is That Although 4strokes Are Easier To Ride
Rich Rohrich said:Thermodynamics has little if anything to do with the power differences. It's just a matter of BMEP averaged over a spread of RPM. A 2:1 ratio was probably fairly logical at a time, but recent results have shown that it's probably time to re-factor things in the 125 class.
mtk said:Sorry, Rich, but you're wrong. They're not called "Thermodynamic Laws" for nothing. They don't take a day off, ever, and this is no exception. Thermodynamics IS the study of engines (among other things); it most certainly is relevant to this discussion.
What you've said is simply the practical, measured application of the aforementioned laws of thermodynamics.
Brake Mean Effective Pressure is derived from the operation of the engine, it's not some magical number you pull out of your butt. Drop the compression ratio of ANY engine and BMEP WILL drop. More importantly, BMEP is an idealized concept in itself and has no actual relation to the actual workings of an engine.
The simple, idealized models place upper limits on what you can get out of an engine. Thermal efficiency increases as compression ratio increases. There's no two ways around it.
Well, then you'd REALLY hate me! :rotfl:BigLou, yes, I hate fart bikes, for no other reason than the awful noises they make.
Micahdawg said:The last thing we need to do is "punish" the big 5 for their hard work.
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