2 stroke tuning help

[bboswell]

I need suggestions on someone in the Conroe area or a "how to" on tuning a KX-125 dirt bike.

My son just got one that was running great but kept fouling plugs (like less than an hour of riding per plug).

He tried leaning out the gas mix which didn't help and was a bad idea.

I want to find someone to get it tuned correctly before he melts a piston or something.

[Walker]

Man, its hard to foul plugs nowdays. Id start with fresh gas/mixture.

[2coolforschool]

Leaning the oil/gas mix (higher ratio of gas per unit of premix) will actually make the bike run richer as far as fuel/air goes. Is he just putting around, are riding wide open for the most part? Probably need a smaller main jet and needle adjustment.

[bboswell]

Leaning the oil/gas mix (higher ratio of gas per unit of premix) will actually make the bike run richer as far as fuel/air goes. Is he just putting around, are riding wide open for the most part? Probably need a smaller main jet and needle adjustment.

Very little putting around, mainly getting on it constantly.

Gas/oil mix is new and fresh.

[Walker]

Check that the choke valve is fully open with the choke off. And clean air filter

[XBOW STALKER]

Sounds like a crank seal is out. It will suck tranny oil into the top end and foul plugs. Might need crank and bearings to. Good luck

[125Dad]

How old it the piston and ring?

[Pushbutton2]

What octane gas and ratio.
My buddy runs 93 octane at 50:1
In his boys dirt bikes.

He says if that doesn't help try 89 than if that doesn't work try 87

[2coolforschool]

Sounds like a crank seal is out. It will suck tranny oil into the top end and foul plugs. Might need crank and bearings to. Good luck

Strong possibility and something I didn’t even think about.

[bboswell]

Sounds like a crank seal is out. It will suck tranny oil into the top end and foul plugs. Might need crank and bearings to. Good luck

Strong possibility and something I didn’t even think about.

I will investigate this further as I think it has the most merit. I was just looking at it and noticed that there is oily residue coming out of the exhaust that I think is way too oily to just be from running rich.

Thanks!

[bboswell]

How old it the piston and ring?

No clue. 2003 bike but he just go it a couple of weeks ago.

[Walker]

If its.sucking tran fluid up then it will be forcing fuel mixture down guaranteed. Check tran fluid for fuel dilution.