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Posted

Ok I have tried googleing what they are as well but the only thing it shows me is where to buy one at . I wanna know what makes a cheeta a cheeta or a cub a cub, and what is the diffrence between them. Any help would be grealty appericated thanks.

Posted

The Cheetahs have power valves, the Cubs don't. Also the Cheetahs use a bigger intake and reed cage, while the Cubs are made to use all the stock parts.

Posted

The Cheetahs have power valves, the Cubs don't. Also the Cheetahs use a bigger intake and reed cage, while the Cubs are made to use all the stock parts.

 

Power valves ? Hmm But 2 strokes dont have valves so what is a power valve.

Posted

Powervalves are basically an exhaust valve that is actuated using either electricity or vacuum, since the banshee has no cam to run the valve. That's the best description of it I can give you, if someone else can do better, please feel free to jump in and do so.

Posted

I got you a better explanation from Eric Gorr's website.

 

 

How Exhaust Valves Work

 

An exhaust valve system is designed to increase the engine's low-end and midrange power. There are three different designs of exhaust valve systems. The first-generation design uses a variable-volume chamber mounted to the head pipe to change the tuned length of the head pipe. A butterfly valve is used to separate the surge chamber and the head pipe. At low rpm, the valve is open to allow the pressure waves in the pipe to travel into the surge chamber and effectively lengthen the pipe and reduce the pressure wave's magnitude when it returns to the exhaust port. These systems were primitive and not very effective on 125cc dirt bikes. Honda and Suzuki used this type of exhaust valve system in the mid to late 1980s.

 

The second-generation design features valves that control the effective stroke and the time-area of the exhaust port. These valves are fitted to the sub-exhaust ports and the main exhaust port. The main exhaust-port valves operate within close proximity to the piston to control the effective stroke of the engine. The effective stroke is defined as the distance from TDC to when the exhaust port opens. At low rpm, the engine needs a long effective stroke, which results in a high compression ratio. At high rpm, the engine needs a shorter effective stroke, longer exhaust duration, greater time-area, and a lower compression ratio. Yamaha used this system starting in 1982 on the YZ250. Honda's HPP system is similar and was used on the 1986

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