I couldn

[Blue Duece]

The real difference is that the passion is hitting 27HP before 5000rpm.

 

.

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thats what ive allways said..... my bike has decent nuts right when it comes on, making it ideal for mx, and open racing....... not to mention the top end is all there

[Banchetta]

I understand Harmonics and I understand Phase consolation, but I can get my brain around what you are saying.

 

The harmonics from what forcing frequencies, are you talking about? I think you

[PUSH THE THROTTLE]

In other words, imagine this.....your exhaust is leaving the cylinder at a fast rate and all at once creating a wave effect. ONce that wave gets further away from the cylinder, it creates a small vaccuum by the cylinder since the exhaust opening is now closed and the wave is still exiting the pipe. Once the piston opens the exhaust port back up for the second time, the vacuum helps pull the exhaust out creating a turbo effect, so now you have exhaust being pushed out from the cylinder and the vacuum pulling it out from the pipe. Thats why port timing and pipe timing are so crucial...This is also probably why its so hard to get the strokers to work. ALL pipes are designed for stock porting and stock cranks.....Who wants to build a stroker pipe???   BTW, four strokes have the same effect, just not that dramatic since the 2-stroke pipes control the wave and the reeds are effected by that, where as the 4-strokes have mechanical valves. Thats why 4-strokes need backpressure, its the timing of the wave.....

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That makes sense to me. I don't really know anything about powervalves but how does an RZ motored Banshee compare on the dyno?

[RNBRAD]

In other words, imagine this.....your exhaust is leaving the cylinder at a fast rate and all at once creating a wave effect. ONce that wave gets further away from the cylinder, it creates a small vaccuum by the cylinder since the exhaust opening is now closed and the wave is still exiting the pipe. Once the piston opens the exhaust port back up for the second time, the vacuum helps pull the exhaust out creating a turbo effect, so now you have exhaust being pushed out from the cylinder and the vacuum pulling it out from the pipe. Thats why port timing and pipe timing are so crucial...This is also probably why its so hard to get the strokers to work. ALL pipes are designed for stock porting and stock cranks.....Who wants to build a stroker pipe???   BTW, four strokes have the same effect, just not that dramatic since the 2-stroke pipes control the wave and the reeds are effected by that, where as the 4-strokes have mechanical valves. Thats why 4-strokes need backpressure, its the timing of the wave.....

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Like Banchetta said this exhaust wave from the forces of hot gases creates a sonic wave down the pipe, then it reaches the diffuser channel and the wave reverses itself, returning back to the exhaust port. The TIMING of this resultant mixture of unspent gasses are further used to pressurize the next combustion mixture. Thats why pipes with the correct diffuser size and length is so important for the proper timing. So that this reversed wave hits the exhaust port at the proper time before it closes and you loose the benefit of this pressure wave. This is the most critical part of tuning a 2 stroke motor no doubt.

[Redlined]

Thanks guys. I understand what you are referring to now. I have heard a little about this in the past but need to learn some more.

 

So my research begins

[Banchetta]

That makes sense to me.  I don't really know anything about powervalves but how does an RZ motored Banshee compare on the dyno?

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I don't kow, never dynoed a powervalved shee. If I had some T-rex cylinders, then maybe that'll just solve the problems we've been looking for....

[boonman]

The only way to get a silky smooth powerband on a two stroke is with a powervalve. It is physics of a 2 stroke engine that limit it's prowess in this area. It's like variable valve timing in a 4 banger. (think "VTEC") It allows the engine to pull the exhaust out better at lower RPM when the powervalve opens, and lets the pipe work better at higher RPM's when the valve closes.... Or vice versa. It's late and I've had a few drinks..... Either way, it works...... (whichever way it is.... )

[D34]

It's late and I've had a few drinks.....

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me 2...