Dear Mr. Know-It-All,

I’m having grief with my 2021 KTM 300XC. For no apparent reason, it started bogging and running a bit rough at all throttle openings. I’ve changed the inline fuel filter and cleaned the air filter. Not having a carb to clean, I don’t know where else to start. Please help!
Lyle Durst
via [email protected]

There are several items to check, and while it could be something electrical, one of the easiest places to start is the brass nipple and tube coming off the cylinder for the crankcase pressure sensor. Basically, with a decent amount of trail time, the brass nipple and tube can become clogged with debris, carbon, oil and dirt, and the bike’s sensor will be getting a bad reading, and the ECU won’t know how to compensate. Remove the exhaust and take off the black tube, then use an 8mm-deep socket to remove the nipple. Blow some contact cleaner and compressed air through both as if it were a jet in a carburetor. You should see some black gunk come out of them and, with luck, your TPI machine will be happy and reward you with a smooth and potent bark.

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