So we should be more concerned with where the engine starts making torque? Then at that point, is it more beneficial for 4 stroke engines to be modified for torque engagement at a higher rpm, or will that not make a difference?
essentially yes.. but that might not pay out.
belt drives do not like torque, it makes the belt slip.
they like rpms more (inertial difference is small..less slip on the belt)
30hp @ 13000 rpm isn't impossible on two strokes,
getting to 20 horses @ 8000 rpm is quite a task for a industrial engine already
So the only way to increase power further would be to go bigger in volume
and that always also increases low end torque.
To a point where it might again be beyond what the TC can handle
at those lower speeds...
And while a torque@rpm table would be nicer to have as a TC rating
in order to be able to make the best decision.
the more general 4stroke vs 2stroke hp rating is essentially what it boils down to
and the less inclined user is still able to follow along.
Okay other way around example:
the series 30 is rated 8hp (both actually, 2 and 4 strokes IIRC)
slap a gx200 on it modded and pushing 10 or 11 horses @ 7000 rpm
since all the horses are in the upper rpm band
and no real torque improvement had been done, the TC will not care
now instead get the compression ratio up as high as you can
grind yourself a torquer cam and retard timing by a few degrees
to get the best bang at just 2800-3000 rpm
and you'll have a nasty low end torque and no noteworthy hp gain
staying below the 8hp rating even
but the series 30 belt will likely have to be replaced every other time
because the low end is just above what the tc belt can handle.
and more compares to the low end of a gx390 13hp engine
than a say gx240 it'd still be rated for
Correct me if I'm wrong, but from my understanding of dirtbikes, four strokes make lots of low end torque, while two strokes make lots of high end power and can rev. That's why four stroke bikes can take the inside line, while two strokes take the outside of a turn.
I wouldn't say that 2strokes cannot take the inside line
(2 strokers need to shift more during a race usually.. but that's about it)
and while 2 strokers likely need more rpm in a turn,
they are unlikely at significantly higher speeds in that turn
same speed = same line is fine to assume
(the rider is the most important variable really)
And past the apex all riders prefere the 'faster' outside anyways
'sid
