Motorcycle Repair: Fouled Spark Plugs, stroke cycle engines, ktm 250

Question
Hi Mark, I recently purchase a 2003 KTM 250 (2stroke) It appears to have been well maintained by the prior owner, he kept detailed records completed by the dealer.  The first time I took it to the track it fouled a spark plug within :30 minnutes of riding.  Since I had just purchased the bike I just replaced the plug with the manuf. recommended replacement with the correct gap.  With the new plug installed, I go riding 10+ hours in the california desert - no problems even with many restarts.  I get the bike home off the trailer, start it, a foul the plug in 1 minute.  Are 2 strokes this sensitive to spark plugs?, Do you think something else could be wrong? and What is the recommended replacement time frame for replacement.  Thanks in advance + best regards,  Russ

Answer
Hi Russ,

Two-stroke cycle engines may foul a plug on once in a while. Usually they are dependable and have no problems.

Some riders lug the engine when riding and load up the plugs. If the carburetor needs tuning or if there's an ignition problem, plugs may foul.

Check the air cleaner for intake restrictions.

Check the igniton system including the engine control modlue (ECM) or black box.

Basic troubleshooting should resolve the problem.

I return tech information files by email. There was no email address with your question as requested.

Respectfully,
Mark Shively