Bottom line is that when tuned for max power the disc valve does make more than a reed - those flapper things are always "in the way" to some extent..
But there are many trade offs.The disc will have NO power at all under the tuned for range, as it cannot suppress reversion at low rpm, and you cannot tune out the fact that the intake waves are telling the main jet signal all manner of lies,repeatedly.
Thus a reed engine can have much wilder exhaust timing and pipe design without giving away a heap of "under the pipe" power, and this exhaust tuning can have plenty of overev power as well, if that's what is needed.
An example would be the pipes I did for the fastest,and record breaking Honda RS250 on the salt last year, it had over 90RWHp between 12000 and nearly 15000,so would simply keep revving till the aero drag stopped it.
The peak power was "only" 96 I think, but it had plenty everywhere else it was needed.
To get that sort of overev power from the RV would mean it would be all but impossible to get it to carburate off the pipe, as the closing timing needed to get to 15000 would be mentally wild ( like 98*+ ).
And the last thing to consider is that despite what the supremely clever Frits and Jan say and did - in the last year of 250GP a Honda reed valve engine kicked Aprillias arse in the title - with a guy who cant ride a MotoGP bike to save himself.
The newer RSA engine is probably an unbeatable combination in 125GP, but for many other less demanding applications the reed has real, and useable, advantages.
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Originally Posted by TZ350
(Alongside the fat spannies on the Metrallas)
(in the kitchen)
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