My initial setup on my PX125 disc was Polini177 (no porting) Sito plus exhaust,20/20 carb, 108 main jet and BH7s spark plug, built by MSC and ran without problems, done about 8000 miles.
I then upgraded the carb to 26/26 and upjetted main jet to 120 and same again ran fine even at top speed.
I have now went for Simonini and upjetted to 125 main jet but on my first run out at full throttle and roughly 70 mph the piston siezed and I pulled the cluth before I was thrown of the scoot, I started her back up 5 mins later and all was OK, and ran her for another half hour to see if any damage and she ran fine but I did not go up to full throttle and I was shitting it. I still had the BH7s in but I have just changed it to a Bosch WCA3 which is equivilant to BH8S, could this have caused the seizure?
Is the main jet to lean?
Should I go back to Sito plus, the Simonini seems a big improvement I must say but do not want to ride my scoot every day with my fingers on the clutch feeling nervous, I would like to keep the Simonini if anyone has any suggestions
I recently decoked the Cylinder and did not use a torque rench to tighten the head back on, could this cause piston seizye? help please…