Fouling Plugs

I have a 2002 yam 426 with JD Jetting. Tried blue#4, Red #5 and still after a couple of rides plug fouls. Anybody have any problems with there plugs fouling? I ride in Mi around 1000ft. I'm getting tired of changing the plug, its not like the old air cooled fourstroke that took 2 minutes to change, then again my old suzuki dr 350 never fouled a plug. Any suggestions will be appreciated. Thanks

you are way to rich..............

u must have jetted it to rich. go back to stock jetting and go from there, or swap out one jet at a time and see what the difference is

Try the stock jetting and a new plug and see what happens... if its still fouling up plugs maybe try leaning the needle one position, Thats what worked for mine anyway.

Use the 165 or 168 main jet, blue #3 and fuel screw set at about .75 to 1 turn out. Its a little fat on the fuel dude! I ride about the same levels, but on a 450, and have found this set up to be good.

Thanks, the next time I ride I will try blue #3 and red #4 with a 168mj. Hopefully that will cure the plug problem.

Often the pilot jet is too rich and the main cause of fouling. Needle is primarily 1/4 to 3/4 throttle and main is mostly WFO. Thus unless you are a desert racer wide open all the time fouling is typically from over rich slow speed circuit, not the main and typically not the needle. YMMV :D

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