Originally Posted by
NJA82
Although i will agree with you that the "current" 4 stroke 450cc moto`s are superior in power to the older gen 250 2 strokes, i have to say that the reason you dont see them anymore on the track is emission laws, they outlawed 2 strokes for racing a few years back hence why every manafacturer jumped into 4 strokes.
The very first production 450`s werent as powerful as they are now and a well setup 250 2 stroke was still a faster, lighter and more nimble bike for racing, 4 strokes make it easier for the novice rider to go fast, making the sport more freindly for new comers, 2 strokes are an experts engine when you start making big power because the powerband tends to be narrower. But they are a lot cheaper to rebuild, have a lot less moving parts and weigh a lot less, the current 450 bikes are a bit over 100kg, whereas the factory 250`s of the late 90`s and early 00`s were more around the 90-95kg mark, thats a big difference in the air and under braking etc.
All these comparisons work hand in hand with R/C, the motocross industry were forced into engine changes from laws getting tougher, our industry hasnt got these laws and the cheap, light, simple nature of a 2 stroke IMO will be the reason we will stay that way for a few years to come, unless something comes along that forces change... although fuel and emissions arent a problem with alcohol fueled engines.
just to clear a couple things up: sure, the government was going to get its way with the emission laws....however, yamaha jumped the gun waaaay early with their 400. these early big bore 4 strokes (specifically 426) were VIOLENT with power. they only continue to smooth them out year after year.
as for the weight, you don't even notice it. the reference to braking isn't really applicable since the engine-brake of the 4 strokes is so crazy. as you go through acceleration bumps, the bikes track so much better too, which makes them feel 10x lighter (you don't have the bike swapping all around under you). also, they are much easier to jump.
Originally Posted by
Davidka
A current 250cc 4 stroke would eat a 2 stroke 250 on the track, not with peak hp, with drievability (though I imagine at this point they're pretty close in HP). 4-strokes were first driven into motocross by the manufacturer
exactly
in RC, it's awesome to watch a little 4 stroke rip around. however, for all those ex mx-ers at the track, nothing beats the current sound of 1/8s racing. the sound is as close as you can get to the old mx days
