All-Of-A-Sudden Severe Plug Fouling

[Brian]

:whiner: My 01 KTM 250 decided to start fouling plugs overnight. Jetting has been very good lately(175/45, CEJ-3) and one day it happened. It will foul a plug nearly every time it is started. If it doesn't foul the plug, it will just run poorly and not "clean out"(ie sputter)

I just spent bookoos of money on new crank seals and bearings as I thought that was the problem. Nope. I just put in the factory needle that used to make it run lean(NOZG-3) and it is still eating plugs. When riding, the bike will "load up" and need cleaning out again. That is typically when it will foul the plug. Everythingh looks OK in the carb, and the float level is correct. What puzzles me most is why this happened all of a sudden.

Any suggestions are welcome, as I am desperate...

 

[KawieKX125]

Sounds like a problem I had with my old RM80. Turned out to be the ignition. A "new" used CDI box I had solved the problem. The only other ideas I have is that your right side crank seal is leaking, I know you replaced it but maybe there is a burr on the crank journal or something like that.
Hope that helps.

 

[elf]

Thats weird, I am assuming there is not a rag in your air box or carb. How about the ignition? I know on ktms they go bad on occasion.

 

[rico3320]

I have a cr85 expert 03 and its doing the same thing. Somethimes it will run fine but then the plug will just foul and ill clean it up good it will run for 5 sec then foul agin.

 

[Studboy]

I had that happen once on my KX250. The carb looked clean, but there must have been condensation or something in the air passages. I cleaned them out and all was well again.

 

[Fred T]

Check your reed block and reeds. Also check the needle and seat in the float bowl.

 

[Brian]

It has a new crank, as well. I just came up with the idea that the float needle may be bad. I'll check it and pray that it is.

 

[CR Swade]

Our last ride in the mountains @ Arkansas had a KX250 start to do that. He fouled two plugs over roughly 1 mile of trail...turns out he had crud frozen up in the vent lines. We cleaned them trail side (carb stayed on the bike and wasn't moved) and he ran fine. Yours may be some mud that is up in the line just far enough that you can't see it by visual inspection. My other inclination past that would be ignition.

 

[CJG]

In addition to what everyone else has said, and you've probably already done it, check to make sure your pilot jet has not come loose allowing fuel to get around the threads. It sounds crazy, but it happens.

 

[Brian]

I took it to the shop that put a crank, bearings and seals in it and he looked at a couple of things and swears up and down that they messed up putting the wet side seal on. I should know by tomorrow...

 

[BarkSlayer]

If it were a wet side seal, you'd be belching thick white smoke the whole time it was running.

 

[DocLeach]

I would also check your spark plug cap (ignition cap). I had a kx125 that did that until I put a new one on.

 

[Brian]

How do I check the spark plug cap?

 

[GhostRider32]

Our last ride in the mountains @ Arkansas had a KX250 start to do that. He fouled two plugs over roughly 1 mile of trail...turns out he had crud frozen up in the vent lines. We cleaned them trail side (carb stayed on the bike and wasn't moved) and he ran fine. Yours may be some mud that is up in the line just far enough that you can't see it by visual inspection. My other inclination past that would be ignition.

I know this is off this subject but where in Arkansas were you riding?

 

[2smoke]

Check the crank seal...gearbox oil into the motor will cause fouling but as pointed out previously she would be smokey.
Failing that check the ignition and wiring loom just incase anything is loose.

Also do you use fresh fuel. When unleaded fuel came in you couldn't use fuel mixed the day before (leaded was good for lazy bums like me) result was instant fouling.

 

[Jeff Gilbert]

Hey Stan, check your fork seals. :p

 

[CR Swade]

I know this is off this subject but where in Arkansas were you riding?

White Rock, near Cass