You haven't even said which prop, fuel and plug are you using...give us more info about it, and then we could help you (try).

If you don't want to tinker with it and try to find what is wrong, it is just a waste of time (no offense is intended)... most people around here have experience and when someone have problems, normally a solution is found, but if you just want to replace it with the Saito... doesn't make much sense...

Saludos