86 R fouling lots of plugs

[seth400]

hello, ive got an 86 250R, its been bored .080 over, and it has a dg silencer, and i think the headpipe is stock, but it could be an aftermarket one. i bought this quad back in november, and when i bought it, it had a .155 main jet in it, and was fouling plugs alot, i dropped down to a .140 jet and she doesnt foul as bad now, but is still fouling plugs all the time. i went riding saturday, and fouled a plug after riding for like a half hour. what could be the problem? could it be the pilot jet? any thoughts would be greatly appriciated. thanks

[4TraxRider]

What does your plau look like when you take it out. Maby your still a little to rich. It also could be the two stoke oil and gas your using. Cheap gas and oil foul plugs a lot easier than the good stuff. Or maby you gotta wick it open a little more.;)

[AndrewRRR]

It's been a long time since I have had a stock carb but I think .140 is smaller than stock! Sounds like you have more jetting to do. You should find out what pilot you are running and what needle position you are in. Do a plug chop to determine if it's the main jet or not (hold it wide open through about 5th gear, hit the kill switch and pull in the clutch, then pull the plug, it should be a nice chocolate color, whiter is lean, darker is rich). If you do a lot of low rpm riding it is probably your pilot or needle, I couldn't imagine a 140 main fouling plugs.

[DaveEX7]

this probably has nothing to do with it but i rode my friends bike and when i started out i stalled it twice cause it was cold out and he said jeez im gonna haveta change the plug cause u cant keep startin it that many times

so mabe ur startin it too many times ina row, juss throwin some ideas at u

[oynot400]

One of my friends has a '88 R. He was having the same problem, he would foul a plug about every hour of riding. After asking around here, he changed the crank seal on the clutch side. If the crank seal is leaking on the clutch side it will make the engine run rich. If the seal on the flywheel side is leaking it will make it run lean. He replaced both, and it helped out quite a bit. He still doesn't have it dialed completely in, but it is closer than it was.
Hope this helps....

[OutlawEX]

check ur pilot

[seth400]

how hard is it to replace a crank seal?

[oynot400]

I did not help him do it. He said it wasn't too bad of a job. He replaced both while he was doing it. He said the biggest thing was getting the right flywheel puller from the Honda shop. :rolleyes: