crf 100 plug black!@#$%^&*

for a few weeks my brother crf 100 wouldnt start. so today i went down to the shop. and bought a spark plug. so i put it in and rode it for about 5 mins when i toke it out it was black, when i was riding it would back fire a couple times. i warmed it up for couple mins and rode it around. within 5 mins it was dark. what should i do?. whats wrong with it. its been ridin 10 hours. toatal, and its 04 model.

Its running rich. Make sure the air filter is clean and not oiled to much as that can cause it sometimes. Other than that you are going to have to rejet it, probably go down a size on the main jet.

Turn the choke off.

LOL good point, but I sure hope that isnt the case. I dont think so as if they kept thte choke on the bike wouldnt run very good at all, he just said the plug is getting black.

LOL good point, but I sure hope that isnt the case. I dont think so as if they kept thte choke on the bike wouldnt run very good at all, he just said the plug is getting black.

My point was just to always start with the obvious. :-)

Your right, it was something pretty obvious, didnt even cross my mind either.

My concern would be, "what's up with the backfire?"

When and what are you doing when it backfires?

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