I have a Italian GP 200 engine all standard spec. except for 12v Varitronic.
Total rebuild original GP200 cylinder, stub no6. rebored to 66.6
N.o.s. 3 ring Asso piston from Rimini.
Started running in, at 340 miles riding at 40 mph she locked up.
Cylinder off piston had nipped up by exhaust port.I had fitted new high tensile cylinder studs which i thought had caused the heat seize,
so i had the shaft reduced to 7mm.
Continued running in and at 970 miles riding at 40mph up a 1/4 mile long hill locked up again.
Cylinder off piston had nipped as before, but the underside of piston is black with heavy build up of carbon. the conrod small end and bearing are showing overheating colour.
It looks like i have been riding for the last 600 miles at the point of heating seizing.
My question is would it be safe to use 2 piston rings (less friction less heat)
Spec. Piston to bore .003
Ring gap .012
Squish 1.1
Scootopia sh2/22 carb
choke 50
pilot 45
main 123
jets are Delorto.
regards phil.