Originally posted by Cartman
you will need to change piston/liner crank and also the CARB if its not 5.2mm
Carb is easy. You can use whatever you have just as long as you make sure you use the insert and you're legal.
For crankshaft, EFRA has a crankshaft restriction which is max 7mm bore, no scoops joining into the bore unlike IFMAR. For the piston / sleeve liner, both IFMAR and EFRA does not have any exhaust port restriction either.
p/s: I may be wrong but I thought the exhaust pipe diameter outlet should be 5.2 mm max and that the carb is 5.4 mm max...