After delivering the TSM last Tuesday the bike seized, apparently at fast top speed going up hill and returned to the shop that same night for a check up. That was a first for me in 2 straight years of building engines.
I’m not sure what caused the engine to seize but it happened on a very hot day. It might have been of combination of overheating, the 19mm 4 stroke carb slightly too lean, the 70cc kit revving too high up hill with the launch lever pressed for too long, points ignition rotor slipping, or probably an air leak from the old 50cc head gasket unevenly cut by the previous owner to fit the 70cc cylinder… I could have probably saved the cylinder but the piston was ruined.
I got new parts from Treats Friday night and rebuilt the engine with a new polini 70cc kit + head, bigger 21mm 2 stroke carb and MVT Millenium cdi ignition. I also toned down the engine with a smaller rear sprocket, heavier variator weights, doppler exhaust extra spacer, no porting and retarded the timing to keep the temperature down.
During the summer season most air cooled moped engines suffer a lot, especially peugeot kitted engines because of their small fins matching the stock engine’s look. It’s probably safer not to hold top speed for long period of time.
I’ve been riding and breaking in the new polini kit the entire weekend. The bike feels good with less rpms but still plenty of power and hopefully more reliability under any riding conditions, traffic, top speed, hills, high temperature, excessive use of the launch lever, etc…
The bike is ready for take two.
Test run on Hollywood Blvd.