Hello,

I just purchased a 2002 KX 125. Very nice shape with what looks to be little use. I got it at a pretty good price. Below avrage for around here. But I didn't check it out before purchasing the way I would ahve liked to. I had him start it and run the bike for about 2 minutes in the back of his truck. I didn't even ride it. It was smoking alot but he said he didn't ride it much in the last 2 years. I figured it was old gas. I think he said he also mixed at 40:1. Paid him, then unloaded it from his truck and put it in my trailer. The bike sat in my trailer at my campsite for three days before I brought it home. I unloaded the bike, started it and ride it in my cul-de-sac for about 2 minutes. Never got out of 2nd gear. Then parked it in the garage. I noticed a BUNCH of oil dripping out of the slincer. It was all over the tire and rear brake. I'm talking a LOT of oil. I figure the main bearing seal is toast. Until I checked the colant in the rad, something I forgot to do when inspecting the bike. There is oil in there too. ???? If the main bearing is toast, would oil get in the rad? Or is it possible that its not the main bearing seal.

Your thoughts would greatly be appreciated.

Stablock said:

its a smoker not a 4 stroke, i dont see anyway oil could get in the rads. the coolant level has nothing to do with a crank seal. you are thinking water pump seal. you want to pay attention to tranny oil getting in the motor. best thing to do is a leak down test.

Change out all the fluids, then try again.

Yeah it makes sence the only reason oil can get in the rad is water pump seal. That should mean I have water in my engine oil too right? I'm gonna drain the oil and see what I find.

So what what about the excessive oil from the silencer? I know its not a 4 stroke. Granted. But that much? I mean its dripping all over the place. And that was only after a few minutes.

How do you do a leak down test?

Stablock said:

correct

Stablock said:

you misunderstood. what i meant by its not a 4 stroke, is that oil is pum ped all throughtout a 4 stroke and comes close to the water passages in many places in the motor (head gasket, base gasket depending on model, h20 pump, valve cover area etc). a smoker gets its oil from the gas obviously, so there is no way to transmit oil to the rads excpet tranny oil from the h2o pump. 4 strokes dont sppoge at all or shouldnt anyway. spooge can be caused by a bad crank seal, bad or broken reeds, a silencer that needs to be repacked and is soaked with oil, too rich jetting- not to be confused with premix ratio, or you may not be riding it hard enough to get warm with your current jetting.premix ratio will not cause spooge. spooge is caused by insufficient combustion temps, or a motor that isnt in good mechanical condition. your dealer can do a leak down test for you, you can buy the motion pro leak down kit for way to much money, or make your own for about $10 at homedepot. if ya wanna make your own, ill make a write up later, im at work.

That would be greatly appreciated if you can write it up how to do a leak down test. That would be great. I would rather do it myself then take it to a dealer. I enjoy working on bikes. I've rebuilt many 2 strokes but never a 4 stroke.

I drained my tranny oil. Very clean. No water in it.

So it sounds like I have a few porblems.

Main brearing seal leaking Or one of the things you mentioned above.. That would explain the terrible oil leaking out the pipe.

And some other seal leaking allowing gas/oil in the rad. ??? Although it smells and looks like oil only. not gas. Unless its getting in there after burning. ???


I think I'll do what Dennis suggested. Change all the fludis. Then I'll run the snot out of it watching closely the tranny oil.

Stablock said:

if you smell gas in the coolant, then the head gasket may be at fault, premix oil can get in the rads that way... but there would little oil compared to a 4T. how does the plug look?

My brother's 03 kx125 was messy too. Spooge all over the pipe and swingarm.

Try this:
-new spark plug
-check the jetting
-check the ignition timing marks
-change the main seals
-new muffler packing
-clean the power valve
-new top end might not be a bad idea

Since its almost 8 years old, you might as well change the seals for peace of mind. They are cheap. I think I paid around $12 each for new seals.

Once you get the new seals in, jet the bike.

*be aware of raw oil sitting in the header. our's had about a 1/2 cup of oil ooze out when we removed the pipe

Dirtysnow said:

you make crank seals sound quick and easy. try everything else first, crank seals are the last thing to check