This has the big exhaust from 50cc.nl, can't remember what model it is we had two off them, but it is the one with the bigger expansion chamber, a malossi carb kit which we took 7 hours to tune up, but you have to drop the engine out each time, which is a bit of a pain.
We have taken out the starting clutch assembly, we start it with a power drill which is a lot more reliable at the race track as we learnt to our horror, when the belts we had stretched and we couldn't bump start it.
We are running ball bearings in the gear box at the front now instead of rollers, they happened to be the right size and weight to allow the engine to rev out more before changing up and keeping the top gear down a bit for still max acceleration, with a bit of loss off top end, but on the race track it is about getting out of the chicanes, so thats cool.
Next step is to use a flywheel that has had the magnets and the magnets cage removed, and go for a total loss, we will still use the existing points at this stage, but we will be going for optical after the first race when we have more time.
PS. He wasn't trying to get the wheel up at that point, you do sit quite far back and coming off any rise with power is now enougth to get it up, we were both giggling like girls the first couple of times it started doing it, it really is impresive now!