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Jetting issues on VM28 Mikuni


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Mikuni VM28 and bored to 30mm. Bike is a 94 all stock internals with FMFs and some K&N pod filters compression is at 120psi on both. I have been working and researching trying to get the jetting figured out. No luck. Top end is great but the bottom end and midrange hardly exists. Warm weather makes it act up. I just changed the pilot jets to 30 and I can't even back out the air/fuel screw more than half turn or it will die. The stock carbs had 25 pilots and it ripped so I figured for the bigger carb a 27.5 or 30 would work. Nope same problem. This thing had 50 pilots in it originally and still half turn out on the air/fuel screw was all I could get. Actually seemed to run better with the 50 pilots but had no mid range at all with wet plugs. I have changed needle positions still with no luck. The only thing I think it could be is the "jet valve" or the upper portion that the needle rides in may be an issue. Any input is greatly appreciated. I am not too far from taking it to the local dyno and let them deal with it. Thanks

Edited by BluBanshee98
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