WR-450 Fine Tuning Jetting

'03 WR-450: I have done the airbox mod, grey wire, jetting ,main 160,pilot 48, idle jet 72, jet needle clip 4, zip-ty pilot air screw, breather vent hose to airbox. I have not de-octpused the carb yet. It has great power, excellent snap, plug looks nice. The problem I'm haveing is at intermediate or crusin speeds it stumbles irreg. Need help!! 850' MSL

RNS, where do you live ? A 48 pilot it seems too low and would definietly be for sea level. Either up the pilot jet or adjust the pilot circuit via the fuel screw to eliminate popping at cruise speeds (lean). I live at 5800 ft. and the stock 48 pilot could not be rich enough, went to a 52 and lightened up on the fuel screw. Go figure.

I live in West Central Georgia, LaGrange area. So you think I'm still to lean on the pilot circuit? Thanks for the reply!! : :)

I would leave the pilot alone and try a 155 main jet and see if that leans out your needle slightly. I think you may be rich with the main and it effects the needle somewhat. :)

The humidity went down considerably the last couple of days and I gave it another 1/2 turn on the pilot screw and it runs like an electric motor. Thanks for your help. :)

You are in need of part #5TJ-14916-D1 (OBDUQ Needle) or if you only ride at 800' asl go one richer #5TJ-14916-DP.


I'm not too far from sea level. I had a 48 pilot and I had to open my fuel screw quite a bit. I put in a 50 and it runs alot better on the bottom. If you are running funky at about mid throttle, and running ok on bottom, you may want to tweek your needle, or, try a different one. :)

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