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yz125 greyish oil out of pvbt

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Hey I have a yz125 and it just started to drip a greyish oil out of the power vavle breather tube. Before this it would drip some dark black oil out of it. Any ideas what is causing this? My bike is also running a little rich but I am going to rejet it soon

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I've had a little smoke on start up, no problem. Not sure about the grey...

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Sounds like you might have a water leak on the two head o-rings. Best check it all out.

 

I thought this too, but I don't see how the trans oil would get into the PV compartment.

Edited by rjpjnk

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If you happen to get any water mixed with oil, it turns that a gray or white color.

Lots of time its just powerwashing or condensation, but head o rings can be a culprit.

Has it been sitting outside, or in a super humid place?

Does it smoke any white smoke? (Burning coolant)

Hows your coolant level?

Does it seem to blow coolant? (Compression pressurizes the cooling system)

Is it hard to start after it sits? (Pressurized cooling system blows coolant into the cylinder after the bike stops)

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I thought this too, but I don't see how the trans oil would get into the PV compartment.

I'm just thinking black spooge from oil/gas mix and the inner O-ring on the head making it a greyish color.

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Actually just recently noticed this on both of my bikes, and had never encountered it before.  One was my KX where the airbox was super dirty (bad filter, etc), this could have contributed but idk.  My YZ started experiencing the same thing, clean airbox, but top end was around ~50hrs.  I rebuilt the top end and I can't remember seeing it again, but I've only ridden it once.  If there was a tiny crack in the head that would obviously cause the same thing, but likely with more serious symptoms too.  (Light) smoke out of the PV breather is normal IMO.

Edited by bcssrmz250

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If you happen to get any water mixed with oil, it turns that a gray or white color.

Lots of time its just powerwashing or condensation, but head o rings can be a culprit.

Has it been sitting outside, or in a super humid place?

Does it smoke any white smoke? (Burning coolant)

Hows your coolant level?

Does it seem to blow coolant? (Compression pressurizes the cooling system)

Is it hard to start after it sits? (Pressurized cooling system blows coolant into the cylinder after the bike stops)

I store it my garage

I cant remember if it blew white smoke

Coolant level is still the same right where it should be

no it doesnt blow coolant

Usually starts 1st kick

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I just restarted it today and let it ran for a little more than 5 minutes. No greyish oil this time. Just black oil but if it drips quite a bit does that mean its running to rich or that the powervalve isnt set right?

Edited by ramcharger

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I just restarted it today and let it ran for a little more than 5 minutes. No greyish oil this time. Just black oil but if it drips quite a bit does that mean its running to rich or that the powervalve isnt set right?

 

Probably just rich.  As far as powervalve "set right", if you take the pipe of, shine a flashlight in, and both sides look the same, they just be set right.  There's no real powervalve setting (correct me if I'm wrong).  As long as your link arm (external the motor) is positioned correctly, both push-pins that connect the valves to the main shaft are intact, and the valves are opening/closing in sync, they should be correct.  I had a push pin come out so only one valve was operating and I could tell a difference in power, which you could see by pulling the pipe.

 

I always thought too that it could be because I ride through a lot of water, deeper creeks, etc.  But really that shouldn't have an affect unless the powervalve breather is SUCKING in.  Otherwise you shouldn't have an entrance for external water and it would have to be condensation or coolant.

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Update on my end.  Put a solid hr or more of aggressive track time on the YZ this weekend.  Everything ran great, even passed a few big bore buddies  :thumbsup:  Parked in garage and the next morning a small (50 cent size) all black drip from the PV breather had collected on the floor.  Good news there as it seems the hard riding hadn't indicated any leaking head gaskets, etc.  After a brief wash in the light drizzling rain, blow dry with air compressor, and a 5min run to change the oil, I noticed this.....SUPER thick grey blow-by coming out of breather hose.  This stuff looks like legitimate grease.  My thought is that it's some sort of residue from the lithium I used for assembly, but not sure.  I kinda used cheap grease so it was the black kind, and I only used a little on the inner and outer head rings and the o-ring on for the PV shaft (wherever the manual indicated).  That's my best guess.  This stuff looks way to thick to be coming from condensation.  Bike cranked 2nd kick, coolant level same, and all that, so pretty sure there aren't any leaking gaskets.

 

IMG_20160327_115046623.jpg

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I never have myself always just cleaned up the groves installed dry when it came to those. Always just thought debris or grease on that surface would increase the chance of it leaking.

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it is a good thing to lightly coat the o rings with lithium base grease during assembly 

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it is a good thing to lightly coat the o rings with lithium base grease during assembly 

 

 

On the last piston, I can't quite recall if we put lithium grease on the o-rings or not.....  Kinda like Dirty Harry when he's asking the punk if he thinks he fired 5 or 6 rounds, except my cloudiness was due to age.  However, I did buy a nice new tube of lithium grease today and will be applying a coat to the o-rings when my new piston goes in, as recommended by "Dr. Snider".   :thumbsup:

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Now I'm thinking....what about "bad" or old gas that has collected some water or condensation?  Run that and it mixes with the PV spooge and boom you get the grey stuff?  Just weird that I had this problem too and all things being equal (which they aren't really; new top end, etc) I can't remember it doing this before.  That said, I just filled up the jug with fresh 93 a couple weeks ago, so it hasn't been sitting very long.  Maybe it's just a gas quality issue?  Just throwing this out there.

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I noticed this on my sons freshly rebuilt YZ125 the other day after washing it, and while its running, the discharge from the tube is definitely black.

I know this because it drips on the frame slightly.

I just assumed the water was mixing with the oil while washing and turning grey.

Going to keep a close eye on it though.

 

Fresh gas too, and lithium grease was used on the O-rings.

Edited by 3Deuces

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I noticed this on my sons freshly rebuilt YZ125 the other day after washing it, and while its running, the discharge from the tube is definitely black.

I know this because it drips on the frame slightly.

I just assumed the water was mixing with the oil while washing and turning grey.

Going to keep a close eye on it though.

 

Fresh gas too, and lithium grease was used on the O-rings.

 

Yea I don't have a fancy exhaust plug to use when cleaning, so no doubt some water gets in the rear.  But I'm having a hard time visualizing how it gets from the silencer to the PV.  Probably not likely, and I'm not sure where else it would get in, unless it's just a wet air filter?  Then you're pulling some moisture in from that side, which is collecting in the PV.  That may be more likely.  I too noticed nothing when actually riding though.  Thanks for the feedback.

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