If you still have one of those unreliable 107 motors, you might as well get a new one cause those things were junk. Even the frames were horrible. I had one and the clutch fried in 3 months, had a bent frame too...
I bought a 125cc piranha motor after my SDG fried and it no doubt was more reliable and more powerful than the SDG107. I have bbr Exhaust, uni filter, 14 tooth in the front and 37 in the back. It just flys.