Originally Posted by
Maximo
smoothing the sleeve will not help the motor...exterior sleeve work adds zero power to these motors........... I would not touch the crank either........ my bet is you would lose HP not gain HP with the mods your propose.........Do not cut the sleeve, its a urban myth that sleeve mods add power !!!!
I'm not going to argue with your advise, as I've only been modifying my own motors for about 3 years. I'm sure you know whats up more than I. However I'd like to run something by you guys on the porting.
Its my understanding that when a sleeve is ported, tapered, smoothed and such.. that this increases flow at higher RMP. Also when the fuel charge is thrown from the crank upwards onto the sleeve, that their is a certain amount deflection off the bottom of an un-tapered sleeve. That being said, doesn't the deflection cause an inefficiency? If that deflection of fuel-air was reduced and the ports had a smooth clear path up into the sleeve, wouldn't that increase efficiency?! If you remove the inefficiency's of the motor however minor, you should be able to slightly lean the motor and keep the same performance, thus increasing fuel mileage. Fuel efficiency is the only reason to port a motor in my opinion, as power really isn't increased much at all. Is that an urban legend? Also I get 9-10 minute runs on my RB's at 230 after my mods. Before the mods its 8-9min I've proven this over and over and over again.
One more thing... how does a lighter crank = less power? In every kind of racing, drag racing through motocross, kart, F1, Nascar...ect etc... a lighter crank increases throttle response and efficiency, as it takes less fuel to turn a lighter crank. I do know from my own experience that too light of a crank can effect how an engine idles. Not enough mass to keep it turning... Timing, I rarely mess with except on the WS73 as it needs a bit of a closing side increase because the duration is a bit off on those motors and graet power increases can be made.
I don't know... could all this be BS... maybe

Anyways, this GRP will probably be done as do my others, and I guarantee I'll smoke the stock guys out their.
Peace...