Jet Sizing Info

motorcycles with stock engine and with stock air intake and stock exhaust system . stock Pilot Jets, one size larger Main jets and optional one needle shims for each carburetor.

motorcycles with stock or lightly modified engine with improved air intake using stock air intake box and baffled aftermarket exhaust or lightly modified exhaust. one size larger Pilot Jets, two sizes large Main jets and one needle shim for each carburetor.

motorcycles with stock or lightly modified engines with individual air intakes and baffled aftermarket exhaust system. one size larger Pilot Jets, three or four sizes larger main jets and one needle shim for each carburetor.

motorcycles with lightly modified engines with individual air intakes and non-baffled exhaust system. two size larger Pilot Jets, a set of five or six sizes larger Main Jets and one or two needle shims for each carburetor.

A size larger jet is the next available size. example: one size larger of a 105 is a 108, one size larger of a 40 is a 42, two sizes larger of a 150 is a 155.

Needle shims are used to raise the stock needle to allow for better mid range RPM performance, perfect and cost effective compared to expensive aftermarket needles.