Choose your motorcycle brand and model from the sales drop down list or if not listed choose another brand or model you’d presume to have a similar engine for a good tuning starting point. Please contact our office by phone for advise if needed. Please note that when comparing with American specs that our Australian fuel which comes out of Singapore has completely different performance characteristics in comparison with with that from the US hence why their jetting specs often don’t work here.
Tuner jet kits consist of the suggested jets for changing that are not matching those factory fitted in the VM20-273, they include an extra one size up and one size down main jet for tuning the main circuit due to fuel quality variations, altitude and climate. Testing and conformation of correct main circuit jetting can only be done by physically changing jets and WOT testing.
These tuner jet sets have been determined from thirty years of experience, customer feedback, plus research and development as the Australian Mikuni distributor. From time to time these may not be exactly right for every engine, usually due to changes to porting, compression or numerous other things that contribute to the requirement for additional fine tuning but as a rule our kits are spot on or a very close and useful starting point, but we give no guarantees and sorry do not release kit details or jet size information. If you have your own spec simply purchase the carb and buy any other required jets from the jet pages. This also applies to replacing jets in other VM20’s as the 239 and 332 series needle jet and others items may not match and fit.
Keep in mind that these are suggested specs, and all tuning procedures, as found in our Tuning Tips section must be adhered to for the confirmation of any supplied jet’s compatibility with your engine.