puch sleeper exhaust

has anyone made a sleeper exhaust with a decent powerband out of a stock puch exhaust. If you have, how did you do it. I have been trying tio think of ideas to create a decent expansion chamber in one and I was wondering if your ideas were close to mine. Also, for my calculations, does anyone here know the exhaust-open period, in degrees for a stock 2hp puch cylinder?

Re: puch sleeper exhaust

Don't puch have those removeable baffles? You could try hiding the espansion chaber in a stock pipe kind of like this:

wrong tags

Re: puch sleeper exhaust

brandon eliason's older brother in souix falls south dakota built something like this. he does all kinds of crazy stuff with stock puch parts, he has a bike with a hi-torque puch cylinder that supposedly does like 55 or something sick. it can be done, people who do it are spending their time working on bikes and not on stupid forums. ha.

Re: puch sleeper exhaust

That is too cool.

Re: puch sleeper exhaust

Would you just fabrcate a cone out of sheet steel after calculating all lengths and angles? also, To figure out the lengths of everything, I need the exhaust-open period, in degrees. Does anyone know this for the stock 2hp puch (specifically a Newport L)?

thanks,

Eric

Re: puch sleeper exhaust

What someone else has for a stock puch 2hp cylinder could be different from yours. the exhaust open duration is mainly dependent on the port map, something could be varied between engine model years, so its not a sure thing.

why not just measure it?

the best way probably to pull the head and the flywheel cover, Spin the flywheel until the exhaust port opens, mark both the flywheel and the crankcase. Spin the flywheel in the direction of rotation until the exhaust is just covered back up. Mark the flywheel at the point indicated by the mark you put on the crankcase earlier. Draw a line from each point to the center of the flywheel, measure the angle between the two lines. Voila, your exhaust open duration in degrees.

Re: puch sleeper exhaust

its about 150 degrees stock for a hi-torq, sorry i didnt notice that question earlier. about 160 for a 'old style' aluminum cylinder. One of the main reasons that jug revs a lot higher than the cast-Fe.

also, javapipe comes up with some crazy shit for moped engines with less that 170 deg exhaust duration, not sure why. he says it was written using blairs forumlae (which are crap anyhow) but i've run it with the blair equations and it comes out totally different. I would either use the blair or gordon jenning's formulas. not sure if thats where you were going with this or not, just an important consideration.

Re: puch sleeper exhaust

I am using the Jennings formula. Sorry I didn't specify. I have a hi-torque. I have almost all the calculations done. now how fast do I want to go...?

75 mph, duh!

Re: puch sleeper exhaust

calculate the numbers for the hi-torq around 6000-8000 rpms, thats all the faster you'll be able to push that thing without loosing all your midrange.

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