The owner of the engine just turned up with it and said "see what you can do". He even threw another crank in the box and two sets of carbs.
I've looked at making it bigger using modified NSR150 cylinders. Absolutely no where near being even a bad fit! And on top of that it's only a 2mm increase so would give about 415cc. Not enough.
Paul gave me a b
llocking for even thinking of such a ridiculous thing, and said that it HAS to be over 500cc or there's no point!
Oh well, back to the old drawing board.
Yamaha TZM150 cylinders are 61mm, so that would give us about 444cc, which is getting closer.
The crank looks like it was made just before the invention of the wheel, but I think it could be stroked. Let's say we could stroke it 5mm (possible?...maybe), we would get about 488cc. Still not at the magic number.
Anyway, I could waffle on but it won't get the job done. If it was easy then everybody would have a massively oversize NS400.
If it's any consolation, I bored the carbs out
