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Jetting reaffirmation

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Have an uncorked relatively stock XR4. Uni filter and other minor mods with stock pipe. Starts 1-3 kicks cold, no deceleration pops and zero complaints from 1000 to 5000 ft. Last year when I went up to around 10,000 on a ride it started to be a bugger to start w/o the choke and had a near stall at an in opportune time when I went to loft the front tire. This yr I'd like to clear things up a bit with a jet change. I have needle in the second clip down, 160/60 1 1/4 turns out set up. I don't really have a chance to "Prerun" to get the jetting right and am looking for setup recommendations. The FSM correction chart puts me in the .89 to .90 correction area for the main (160x.90=144) with current temp trends. Thank for answering another jetting question ahead of time.

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I would try 58 with 3 turns.  At the higher elevations, turn screw in one or two turns.  With your current jetting, did you try to crack the throttle open just a slight bit at the higher elevation when starting?  That can help the rich jetting.  Use mikuni's rolloff method to jet the main at your lowest elev. and it should be fine to 10,000 feet.  Main is less critical than pilot circuit.

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I bet it ran like a pig with that jetting. At those 10k elevations I run mine with 45-48 pilot and 145-148 main , needle 2nd from top. Tune the fuel screw for best idle and throttle response off idle after you get to where you're riding.

This jetting is with a UNI air filter, gordon modded exhaust, snorkle removed.

You need to state how your bike is set up in such regard, to get any accurate jetting suggestions.

Edited by Trailryder42

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I bet it ran like a pig with that jetting. At those 10k elevations I run mine with 45-48 pilot and 145-148 main , needle 2nd from top. Tune the fuel screw for best idle and throttle response off idle after you get to where you're riding.
This jetting is with a UNI air filter, gordon modded exhaust, snorkle removed.
You need to state how your bike is set up in such regard, to get any accurate jetting suggestions.

Only thing not done is drilled exhaust

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