Xr400r jetting

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Re: Xr400r jetting

Post by 4Strokes » Wed Mar 08, 2017 12:46 pm

If the bike seems to be running fine throughout the throttle range chances are it's close enough for your elevation. One last step I would do, would be a spark plug reading: How to Read a Spark Plug

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Location: Corvallis
Rides: 1999 XR-400

Re: Xr400r jetting

Post by JMerrell46 » Mon Dec 25, 2017 1:18 pm

Hopefully you got your bike jetted and figured out by now. But in case you haven’t, I just had he same problem with my 99 XR400. Plug was black (indicating too rich), but all other indicators were saying too lean (backfiring/popping, hard to start, rough idle, better on choke, Gordon’s mods complete). Put a 160 and 60 in, runs like a CHAMP!! Forget the plug, listen to the other indicators and richen up your jetting. Happy Trails!

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