Mikuni TM40 Pumper Carb


I've just recently got my hands on a Mikuni TM40 Pumper carb. It has a 165 main jet and a 17.5 slow jet. I'm currently turning up a couple of Aluminium sleeves to fit the manifold and the airbox.

My XR is a 600 which has been taken out to 628cc with a Wiseco high compression piston. I'm running White Bros oversize header pipes and an Arrow Aluminium race can. The inlet tract has been widened and slightly straightened and completely smoothed. The airbox has the usual mods and is running a K&N filter.

Can anyone give me an idea of what jetting I should be using?

Any help would be appreciated

Looks like this was setup for a stock Harley. You won't be able to move the same amount of air. There is an air jet in the air intake side (air filter side). It's at the bottom it is real small and screws out. You will have to go with at least a 1.2. If you can get a 1.3 (that would be better maybe even a 1.4) I haven't seen one yet but, I haven't looked ether. This will supply the extra air you need to make this work. The bigger the air jet the leaner the bottom end, between the pilot and needle curcit. The pilot you have up to a 20 & 22.5 will be good to have on hand. Y-4 needle jet for shure, (maybe a Y-2) you probably have a Y-6. A 9oij-1 needle ( I think you have a 9DHY1-4)and a 135 main or there abouts. This should get the bike to run and give you a place to start. :awww: If you have a few jets (up and down) it will work. I have gray PVC sleaves on mine and they work great. They are glued on and don't move or leak even with sick air time.

It takes some time but, it will be worth it :lol: that's alot of caruretor :lol:borynack@hotmail.com this will be good for others that fallow your foot steps :thumbsup: use the force :lol:

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