Jump to content
Sign in to follow this  

125 that is eating lots of tranny oil

Recommended Posts

My frankenstein yz125 has been running a 99 engine for a while now, but its time this oil leak gets fixed. I'm hoping you TT'ers can diagnose this for me since I am clueless.

 

After a day at the track my tranny will be a few ounces low on oil. I dont have a visible leak at this time, but oil use to leak from the plastic powervalve actuator cover. This makes me wonder about the seal at the powervalve.

 

It may be leaking into the engine..... my jetting is spot on and the ceramic portion of my sparkplug is the correct color. I should note that the metal portion of the plug and the treads are consistently wet and oily.

 

I need to do a topend this weekend anyway, so I'm hoping to take care of this at the same time.

 

 

Share this post


Link to post
Share on other sites

If its burning more oil than what you can see leaking out, more than likely your right side crank seal is leaking trans fluid into your crank case. When was the last time your crank seals were done ?

If your powervalve seal is leaking oil down into your actuator cover, replace it as that burnt oil is full of carbon and crap that you want to be draining out of the powervalve drain hose, not back into engine.

Edited by 05CRF250
  • Like 2

Share this post


Link to post
Share on other sites

I made a DIY leak down tester thread. Build one and test it. I bet you will have air coming from the Trans vent tube. Would need a Trans crank seal

Share this post


Link to post
Share on other sites

Looks like I need a new crank seal... can someone confirm that i am ordering the correct part??

I'm looking at part # 93103-32183-00 which is found in the "crankshaft piston" section of OEM parts.

Yes you are ordering the right part, but I would suggest replacing left side crank seal aswell while your at it.

  • Like 1

Share this post


Link to post
Share on other sites

Went to pull the top end... When I took the side cover off to remove the pv actuator arm it seemed to be completely full of spooge.

so I guess I need the o-ring for the power valve also... Or is there another reason for this?

Share this post


Link to post
Share on other sites

Went to pull the top end... When I took the side cover off to remove the pv actuator arm it seemed to be completely full of spooge.

so I guess I need the o-ring for the power valve also... Or is there another reason for this?

Yes that is what I stated in the first reply to this thread

If your powervalve seal is leaking oil down into your actuator cover, replace it as that burnt oil is full of carbon and crap that you want to be draining out of the powervalve drain hose, not back into engine.

Share this post


Link to post
Share on other sites

I probably had 100 mL ooze out of the side. now I'm wondering if I need to pull apart and clean the bottom end. I like Castrol927 but damn it that stuff can gunk up an engine.

Share this post


Link to post
Share on other sites

I probably had 100 mL ooze out of the side. now I'm wondering if I need to pull apart and clean the bottom end. I like Castrol927 but damn it that stuff can gunk up an engine.

You have two power valve seals. One on the valve shaft up in the jug and one down at the base of the actuator arm located inside the right side crankcase cover. If the upper seal leaks, the lower seal is designed to stop any oil that bypasses the top seal.

If the current lower seal looks suspect I would replace both seals and flush the cases if you think enough was draining back though.

If you don't want to split the cases I would at least flush the transmission and put some fresh oil in there and replace both seals.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×