CR125 Oil fouling

[440racer]

I bought a 93 Cr 125 that had a burnt top end. I had the cylinder bored & plated and installed the rebuilt depend.

After riding it a little I found out the the water pump impeller seals were leaking and I replaced both of them.

Now the bike is fouling plugs like crazy and I replaced the right side crankshaft seal which supposedly can allow oil from the clutch cover to get sucked into the cylinder. When I installed the new seal I noticed that the engine case was scratched pretty good where the bearing went in. I may have scratched it but I didn't pry it out. I screwed a screw into the seal and pulled it out like the manual said. So I smeared a thin coating of jbweld over the scratched area before setting the new seal.

Anyway, the engine is still oil fouling like crazy and I'm at a loss. I don't know if I didn't seal the scratched area well enough or if the oil can be getting in from somewhere else.

Any help would be greatly appreciated.

 

[ellandoh]

with all this work are you sure you're not in need of some rejetting?? what is your indication this is trans oil and not premix oil

 

[440racer]

I've set the jetting at the factory settings and and then also leaned out the needle jet as much as possible, mixed the oil at 32:1, 40:1 and even 50:1. There's so much oil on the plug and exhaust I could probably run it on straight gas and I believe it would still smoke like crazy.

 

[ellandoh]

is it sputtering anywhere in the throttle range?

when you drop the oil is there any missing? measure next time to be sure

 

[440racer]

Yes, it does sputter in the throttle range. Probably about mid throttle.

And no I haven't measured the oil level when drained but I will next time.

I've put some good silicone sealant around the edge where the seal meets the engine case and I'm going to put it back together.

I was also thinking that there's no seal along the shaft for the power valve from down near the water pump up to the valve itself and the area arounsd the valve seems pretty dry but could it come from there? I was also thinking that there could be a leak between the engine halves. Could that be possible?

Thanks,

Scott

 

[ellandoh]

right away if it was mine i would check the reeds if you havent already. lower the pilot jet 1 size to try to stop the sputtering, put new packing in silencer, wash out pipe with gas and decarbon the pipe best i could .......a dirty pipe and silencer will drip oil a long time after a problem has been solved. mix some 32:1 fresh fuel and go ride til i could measure for missing oil. then go from there

PV im not sure
case halves is possible

 

[440racer]

Thanks for the advice. I have one question though.

How do I de-carbon the pipe? I've heard the expression but don't know how.

Thanks,

Scott

 

[440racer]

ellandoh,

A couple of other things:

The reed valves look o.k I guess. They're not cracked and the lay on the assembly flat but do open.

Also, Can you tell me how to re-pack the silencer or point me to link with instructions,

Thanks again for all your help,

Scott

 

[j32]

it might be getting oil in through the center case gasket,and the right side oil seal -is not a (supposed thing it is a fact) so is the center cases gasket!!, some models dont have a center gasket, they use the yamalube or liquid sealer ****, i make one from a roll of gasket material and seal it with shellac-never had a prob
check the reeds
the silencer ? just get new packing material wrap it tightyou can use a rubber band to hold it and slide it in-try klotz oil 40:1
good luck

 

[ellandoh]

the silencer will come apart , all motorsports stores will sell packing with minor instructions which will be all thats necessary, you'll see once you get into it.

decarbon the pipe by using a propane torch, once you get the carbon smoking you can keep it cooking in a spiraling action down the pipe with the right finesse. once all the carbon you can cook is done tap the ashes out and rinse again with gas

ive also heard of guys using ovens but youll have to search on that, or laying the pipe in the bonfire or charcoal grill etc etc

 

[440racer]

Thanks!

I'm going to take all the advice and instruction and give it a shot before I break apart the halves but I'm betting that the leak is there. If so I guess I'll do the whole 9 yards.

Thanks again,

Scott

 

[440racer]

Seems good

Just to let you guys know. Silicone around the edge of the right crank seal seemed to do the trick. I guess the scratch was big enough for oil to get by the seal but now it is not fouling out or blowing oil out the exhaust. Now I'll decarbon the pipe and re-pack the silencer. Thanks for ya'lls help

Scott