question!!!
i had the cylinder oversized to 67,50mm
do i have to change jets ?
i currently use standard for MK2
Main Jet 128
Pilot Jet 48

i assume you would.
You will need to check the plug colour by doing a plug chop. for the main jet you need to take bike out for a run keep it at top revs for couple of mins then kill engine. now check you plug if its white it will need a bigger jet it needs to be a nice tan colour