Mikuni VM Series (VM38-21) - Carburateur de Motoneige 38mm - VM38-21

Hi Bryan, For the correct fitment information and recommendation please contact Mikuni directly: 818-885-1242. ~Danielle, Customer Service, Canada's Motorcycle

This carb will work-- I presume your application is a single carb. You could even move down to a 36mm unless you are interested in maximum performance. You must purchase the appropriate adapter to mate up to your manifold to spigot mount the Mikuni and maybe some cables (throttle and choke). Going from memory, I think the 38 comes with a #40 pilot jet and a 360 main jet. These will likely have to changed to get the proper running in all rpm ranges. I ended up using a #35 pilot and a #340 main in my 1975 Mercury SR 440 but this tuning varies considerably depending on the porting, engine timing ,exhaust and compression. If your machine does not have a temperature gauge , I suggest an inexpensive digital type with the sensor that mounts under the sparkplug. On fan cooled machines proper jetting will yield average cylinder head readings of about 300 degrees F. I do not like to see readings over 340 for any long periods of time -- usually means jetting too lean or load factor too high. Mikuni has excellent online tuning advice but playing with two stroke jetting without cylinder head temperature readings is an expensive gamble that keeps piston retailers and mechanics in business. The properly setup Mikuni gives great fuel economy and the enrichner (choke) atomizes the gas well for good starting and much less chance of flooding , especially when hand starting in extreme cold. Regards rbm

This carb will work and the standard jetting should be fairly close. Follow the Mikuni Tuning Guide which is available from multiple sources online. I am assuming your 500 has a single carb-- if not , two of the 38s would be way too much. If your machine has oil injection there will be issues with cables or linkages unless you eliminate the pump and pre-mix the fuel. regards rbm

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