C15 Tuning/make it go faster

I know this is the Bantam forum, but just wondering if anyone has any ideas or knows a C15 racer who could make some suggestions for my sad discouraged young friend James whos ceefer is slower than my longstroke Bantam. He paid a good price for a good looking race bike (Roger Chalks #3, #1 was on a par with Ginger Molloys works 250 Bultaco and Rod Coleman on the Thomas 250 desmo Manx) that only did 15hp on the brake. I gave him the CR MP article test and he has fitted a B50MX cam and lengthened exhaust, polished ports etc, but no faster. Our pre 63 <250 class leader is on a similar bike, but he is 18 secs a lap faster round Pukekohe. Me thinks he needs some flow bench work or something. Any help greatfully appreciated. Roger was using methanol, James still on avgas.

Hello John,

My first thought on reading this was - fit SS90 cam and appropriate high compression piston. I dont know what the B50 cam will be like, but may not be the right way to go.

So, we know we are running on Avgas, and are only getting 15 bhp. Even if there was a high comp pistion fitted, I would be putting in as much advance as it would take - 102 MON avgas is notoriously slow vburning and you have plenty of pre-ignition saftety with that fuel.

Dont worry about posting this subject on t'website. Theres not much else going on at the minute!

Has the cylinder head been modified to give squish?