Exhaust info

Hello to all, I am a long time Bantam owner (amongst other bikes) and am currently trying to restore a 125 (1955). As it has already deviated so far from production I am going to try and get a little extra out of the engine. One of the first items I am working on is a new exhaust incorporating expansion chamber. I will be fabricating one but would also like to have a fall back option of a manufactured unit. Does anybody have any information regarding a suitable donor unit, I was imagining some sort of jap 125 system. All help would be gratefully received.

I am looking for best power increase rather than a broad band.

A D14 header pipe (with barrel port adaptor) and a Suzuki GT250 X7 RH silencer works quite well

i will post an old print that george todd did on porting and pipe good to 7500 yo 8000 rpm drawing he sold to many

great info

but a little out of date for current racing but a big improvment with the correct exhaust port profiles.

regds
Derek

Many thanks to both of you for the help.