powervalves

[hellride96]

im running a 400 cheetha kit and was wondering how exactly the power valevs

work. and also ive been reading some of the threads in here talking about block off

plates for the valves.

whay would i pay the extra money for the cheetha kit and then block off the power valves which give me my better low to mid range power????

thanks

[BenBB]

I'm not sure how the Cheetah powervalves work, but I'd like to hear it from somebody that knows. Aren't they vacuum-operated?

 

My RZ is electric; it's got a little servo motor that operates the powervalve via cables...

[sheefreak]

Are you asking what actually operates the power valve, or are you wanting to know what the powervalve does to enhance low end power. I am not positive how the cheetah is setup. Most powervalves change the volume of the exhast chamber to get power at the differnt Rpm's. As we all know, no 2-stroke pipe can be built to give extreme power from bottom to top on its own.

[Ruko]

What it does is... there is a plate that slides up and down in the exhaust port so at lower rpm's it closes off the port a little to make the engine think it has low end porting and give more low end power. As the rpm's increase the plate opens to allow the top end to sing. So you can get more aggressive porting and still have some low end power. That's why a lot of guys say the Cubs are more for drag racing. They have the aggressive porting of the Cheetahs but no power valves so they are dead in lower rpm's. The power valve Cheetahs have all the top end but also have good low end power as well. They work very well and give you the best of both worlds. As far as I know the only reason to block off the the power valve is if you are drag racing only and don't want to pay for the low end power if you're not going to use it. I would think that is not as common now that the Cubs are out on the market as you can just get a set of them instead. The only advantage to useing the PV cyl's and blocking off the PV instead of just using Cubs, is the PV cyl's have bigger intakes than the Cubs.

 

Now how it works is actually kinda simple... the exhaust pressure increases as the rpm's increase so the exhaust pressure itself is what opens the valve until it's wide open at wide open throttle.

[hellride96]

thanks ruko, awesome reply, sheds a little light on what exactly im running.

no complaints on the cylinders just like to know how exactly everything works.

[DonnG03shee]

Yea, stretch those cheetahs legs out Bro. Just put it back together and ride it like you stole it. See ya, Hellride96.