Kx65 Pipe

The header and first divergent section determine the rate of exhaust flow out of the cylinder and the headers dia and angle of divergent cone control the speed of that flow rate and reduce heat in the cylinder,then the belly allows for a low pressure area where the waves intersect then travel in different directions,the baffle cones (convergent) section determines the magnitude of the return wave with steeper angles being a harder hit,now the time it takes for that wave to exit the cylinder and travel through the pipe to the convergent angle and reflect back to the cylinder is the pipe timing and it's over all length determines where it starts to boost.Belly dia/volume ideally is matched to the displacement,the angles of the opposed cones control the speed and magnitude of the waves while the stinger controls the bleed off of pressure between waves.
 
I'm curious, what part of the expansion chamber determines the width of the powerband and why? My guess is baffle cone but not sure.
Length and width of the cones. That's why the jog scooter pipes work so well. They have a long expansion cone on the front half and a little shorter cone on the back half.
 
I'm probably gonna add about 7 inches or so to the header to change the powerband to mid rpms. The kx65 header diameter is 1 1/4" but my exhaust port is about 1". Should I add a reducer to the header to meet the exhaust port with the same diameter? If so, where should I reduce it, right after the exhaust port, should the reducer be the first thing I add to the header, or do it gradually (if I can, I'm not sure if I can 1/4" is a small amount to do gradually I would think.)?
 
Last edited:
I'm probably gonna add about 7 inches or so to the header to change the powerband to mid rpms. The kx65 header diameter is 1 1/4" but my exhaust port is about 1". Should I add a reducer to the header to meet the exhaust port with the same diameter? If so, where should I reduce it, right after the exhaust port, should the reducer be the first thing I add to the header, or do it gradually (if I can, I'm not sure if I can 1/4" is a small amount to do gradually I would think.)?
Right at the flange/port stepping up to the pipe's dia.
 
I was lookin up the 50cc jog pipe. I'm looking at the cones and stuff, and idk, I don't see how it would have a wider powerband than the kx65. Maybe I'm wrong, but the kx65 looks like it has longer/shallower angle cones than the jog and the header to diffuser cone transition is way more gradual. Wouldn't that mean the kx65 has a wider powerband than the jog? I just wanna figure this all out before I get it fabbed youtube
99229

99230
 
Last edited:
I personally find it's easier to feel and hear fuel mixture rather than plug chop. If I happen to take my plug out I do look at it and smile when it's chocolatey brown. But to start an engine, warm it up, run it under load, kill and let cool then check for color and try to compare and guess lol. Some people even use a new plug each time! This is straight ludacris lol. Ask the saw guys how they do it.
 
I was lookin up the 50cc jog pipe. I'm looking at the cones and stuff, and idk, I don't see how it would have a wider powerband than the kx65. Maybe I'm wrong, but the kx65 looks like it has longer/shallower angle cones than the jog and the header to diffuser cone transition is way more gradual. Wouldn't that mean the kx65 has a wider powerband than the jog? I just wanna figure this all out before I get it fabbed youtube
View attachment 99229
The belly section on the jog pipe is much bigger and the divergent cone's lead in is tapered and much longer than the kx65 pipe,the baffle cone on the kx65 pipe also is much shorter so steeper angle which has a stronger hit but less width.
 
Back
Top