CR125 fouling plugs

My 04 125 Which I have had no trouble with till now is fouling plugs. Its running a standard jet. 40-1 yamalube 2r. Had a new plug and fouled it after 40mins of trail riding. It had sat for 4 months (with fuel in carb):wacko: I drained carb, new fuel off I went. Done 22 hours on piston. Its not been nana riden either. Carb overhaul?

My 04 125 did the exact same thing. I could put in a new plug and after 30-45 min of riding it would foul. Turned out to be worn rings/piston. Oil would get past the rings and just cover that plug and it couldn't burn fast enough. Check your piston.

Clean the carb. Might not hurt to replace the jets too.

Is it smoking any more than normal? It could be a right side crank seal

Mates following me said it smelt rich like un burnt fuel and it was smoking a bit

I dont know why you would run 40:1 in a 125, i suggest run 32:1.

I've got the exact same bike as you. Mines started that brand new off the showroom floor. I do a lot of trail riding and went through around 4 plugs every time I rode. Called the local honda shop, shop tech told me to adjust the carb needle down one notch, and put a one size hotter plug in it and I've never had a problem since. And I also run my bike 32:1.

hi mate

i bought a 07 cr125 about 8 months ago and right off the bat i was fouling plugs like crazy !

After alot of research i fount out that it wasnt the size of the just but the tape of the throttle needle.

I bought a JD jetting kit, installed it and havent had a problem since!

follow this guys instructions, go to about the 3 minute mark and watch from there, see if ur problem is the same as this guys was having.

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