So i bought a piaggio typhoon for really cheap. Once i got it home and started it it whould run but it whould not rev out. the prev owner had drilled a hole in the exhaust so i bougth a new one. Ive tried main jets from 75 - 98. Rigth now it runs but it wont reach high rpms. It will rev out if i have it on the stand with the wheel in the air. So so far ive tried. New exhaust. Main jets from 75-98. Looked for air leaks around the intake. Changed sparkplug. any ideas.??