Quieter exhaust's

Would the oil from a 2 stroke exhaust eventually clog the fibreglass? This would make it solid to sound and hence reduce it's absorption.

John

Yes it does - and quickly too! I wish I had a quid for every Japanese 80's two stroke silencer from which I have removed the disgustingly full fibreglass padding. Fine to sell them with and - one assumes - important in getting the thing through type testing procedures, but a poor idea longer term.

On a simple two stroke (especially one with a ramp piston) the best thing is a cast iron (or heavy steel made from an old air bottle etc) expansion chamber to deaden the high pitched note which exits into a fairly long pipe. The addition of a removable baffled tube is even better.

Regards,

Kim Siddorn,

Kim, What you describe sounds like the kind of design I already had in mind. I think I will use a thick walled tube and machine a removable endplate (the exhaust comes in at the side) with a perforated steel liner and pack the outer void with fibreglass, then I can replace it when it gets gunged up. I had a DT250 years ago and chopped the box open and ripped out the fibreglass and baffles, it went a lot better after but had the same tinny note to it as my allen scythe has now. Regards, Kev