YZ 125 Plug Eater

[prest989]

My 1999 YZ 125 kills plugs. I isn't like a normal foul, it only kills plug when (ex.) I go hard, then let off the gas into the turn, then accelerate 1/2 way into the birm, and the bike boogs down and dies. It does this when it is hot to. It seems to foul when alot of gas is poured into it. It dosen't just foul the plugs, it kills them, after a plug dies on me, it has no spark, and never sparks again. I run 40.1 mix in my bike, and ride it pretty hard. Also, sometimes it feels as if it is skipping, and the rpms will go down then back up again, even though the throtle stays pinned. Could this be the CDI unit, or what, I really need to know, I kill 4 to 5 plugs a practice.

IM me at prest989 or e-mail me at [email protected], thanks.

 

[nikki]

What plug are you using? I'm guessing you're using a BR9ES. If so, try a BR8ES right away!

I have no clue why the YZ 125's come stock with the 9 heat range when almost everyone I know has to switch to an 8 heat range to prevent fouling. :think:

 

[Can Can Kev]

Originally posted by nikki
What plug are you using? I'm guessing you're using a BR9ES. If so, try a BR8ES right away!

I have no clue why the YZ 125's come stock with the 9 heat range when almost everyone I know has to switch to an 8 heat range to prevent fouling. :think:

with the right jetting a 9 shouldnt foul . i run a 9 and i havent fouled a plug since i re jetted for my pipe

 

[prest989]

Yeah, I'm running at 8 heat range, thats not it.

 

[mxer842]

check your floats for any dirt, that happened on my 80 and it would load up real bad like that coming out of corners.

 

[YZThumper]

Sounds like a crank seal has gone bad. I had this happen to me on a YZ250 I used to own. Usually plugs foul while lugging it around, or starting the bike the day after a long ride. But when the bike starts eating them during a ride at speed, it usually means your sucking oil past the crank seal. Take the stator cover off the left hand side and wiggle the crank shaft side to side. If you have any play, your bearings and seal are shot.

 

[prest989]

No, that can't be it, we just redid the motor a couple months ago, and the carb was just re jetted and cleaned, lol, I've gone threw the whole check up, and can't find a problem.

 

[Jeff Gilbert]

Tiggers kx65 was doing just about the same thing as your bike this weekend, turned out to be some trash in the carb bowl. I pulled the bowl plug out and found the problem, must've been in the gas can or something. She had problems leaking gas out the overflow too, guess it was causing the float to stick some but the majority of the trash seemed to be blocking the main jet.

 

[Jeff Gilbert]

On 2nd thought I'd check the connectors coming from the cdi box. Sounds like you may be loosing contact. When you turn it may be pulling the wires loose a bit. Could also be the kill switch, I've had that happen.

 

[billtx]

I have a 99yz125. It was doing something similar, needed new crank seals. Also check float level and clean the carb.

You may want to measure your trans oil volume before and after a ride to get an idea if it is using a lot.