CBR RR throttle bodies

[jtopiso_imp]

doesnt matter really, and yes, its liquid cooled, and th erevlimiter is around... 11k? or so. BUT.. we were talking about efficiency per cc, right? were talking 30% displacement but 50% of the power. efficient. and whats the advantage: better flowing head and compression. it was a stock bike i daily rode for years... so, taking some compression out available with the liquid cooling from 14: 1 (stock) to lets say, 11;1 and aircooling the same motor, i would guarantee that it still made more hp per cc than the cb is stock tune to stock tune. I also know, that a power commander, open air filter, and aftermarket exhaust showed a 9hp increase on the 390s. they do come with really good heads out of the box, on those, it was fueling and exhaust..

lets get more apples to apples but scale it down. doing nothing more than big bore (170cc) head change, an aftermarket exhaust, and a freer flowing air filter, a grom which is aircooled 125, made by honda at the same time the cbs were/are made, so it has all the same restrictions, etc, will take an 8hp bike to 23-25 hp. with bolt ons. the biggest difference is the head. with just going to a bigger bore and a cam, you might see 12-14. Ive seen a gps verified 95mph a few times on mine. (with a stock lower end). With porting the head, which i have not yet done, there are multiple cases of other ones dynoing up over 30 hp at 180cc on an aircooled honda single and breaking 100 mph.


just because nobody has done it on this platform, doesn't mean it isn't feasible or true.

Well, just to clarify my point:

With volumetric efficiency I am refering to how much air comes into the engine per cycle vs the theoreical maximum. This is about the losses the engine has as a pump (per cycle).

Simplyfying a lot, that (with fuel, of course ) gives you torque.

Then, the quicker you can do that per minute, gives you more power.

So the CB maybe is getting as much air as it can -per cycle. I don't think there is a significant restriction in the TB if by improving this, Honda would have got the same performance with better economy: they wan't as much air in as possible without restrictions, and then they make it "driveable" with smart engine control.

Can you get more power per cc? Yes, making the "pump" to work quicker, i.e. more revs. That probably implies cooling problems, more consumption, worse reliability, or some other things that made Honda decide not to rise the redline a bit more. But I don't think the TB is the limiting factor, as it must be pretty much optimised.

Perhaps on older vehicles, due to manufacturing limitations for mass production, there were several ways to improve induction (e.g. cleaning mould split-lines on casting intake manifolds was an easy way to improve the output on the old Citroën AX ), but with modern vehicles, I don't see much marging there.

(Can you put the redline on the CB 2K rpm higher, like the "Duke"? Probably yes, but, probably honda can't do it safely without hitting emissions problems, or reliability... unless it was liquid cooled, but then, it wouldn't be the CB, would it?)