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Help! Bog at 3/4 Throttle!

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I just got a new 05' LTZ400 with the new Mikuni 37mm carb. At this time, no one has any jet kits available for this. I am stuck playing with this myself. I was able to pick up a Alba racing needle and am now at a 155 main middle clip of the needle and 25 PJ. Stock was a 130 Main and 22.5PJ. I have added a Muzzy exhaust and Uni air filter and removed the snorkle and lid.

The quad runs great upd until 3/4 throttle then immediately bogs down like it wants to stall when I hit it further. Am I running too lean or too rich on the MJ?

Before switching out the stock air filter and needle with the uni and alba needle, I was sputtering at 3/4 throttle and up. Now I am popping on decel which I know means it is running too lean, I think I will need to pull the needle up one notch. But the MJ is really throwing me for a loop.

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It's probably rich, but you won't know for sure unless you test in big steps. Try a #145 and #165 main jet to see quickly what direction to move towards.

This is a separate issue from closed throttle jetting, which could still be lean and needs pilot jet/fuel screw or needle clip adjustment.

James

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