2006 CR250 right crankseal leak . Please help

Hondarider68
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Hondarider68
Edited Date/Time 4/19/2023 7:32pm

 my bike just started smoking and sure enough right crank seal needs replaced . i replaced the seal and did a leak down test with the right side cover off . there is air leaking past in between  spacer and spline of crankshaft. 

Is this supposed to be airtight or does the right side cover seal it air tight .

thank you for your help

  cr250seal

 

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DynoDan22
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DynoDan22 4/19/2023 3:02pm
4/19/2023 3:02pm

It will leak if the primary gear is not installed and the bolt tightened. A leaking crank seal usually means the main bearing has some play in it and needs replacing. Have you removed the flywheel cover and checked for up and down movement in the main bearings?  The primary gear must be installed and bolt torqued to check this. 

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Hondarider68
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Hondarider68 4/19/2023 3:16pm
4/19/2023 3:16pm Edited Date/Time 4/19/2023 3:17pm

I have not , I installed the right side seal and pressure tested . The air isn’t leaking around the outer or inner seal surface of the rubber seal , it’s leaking where the metal spacer/collar fits against the crankshaft . I will install a new seal and install and torque down the primary gear and pressure test . I really appreciate your help , thank you again 

I made red arrows in picture where it’s leaking 

1
Last2Stroke 4/19/2023 6:12pm
4/19/2023 6:12pm

As DynoDan22 said, install the primary gear and torque the bolt.

The collar seals against the inner race of the main bearing

 

image-20230420110824-2image-20230420110828-3

If the primary gear is not installed and the bolt not torqued, it will leak past these surfaces and through the splines.

If it still leaks after torque the bolt, there may be debris between the collar and mail bearing, or the collar may be damaged.

3
Hondarider68
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Hondarider68 4/19/2023 6:38pm
4/19/2023 6:38pm

awesome thank you for explaining this . i didnt understand how the surfaces sealed .

now if i can only remember this the next time.

 much appreciated.

  

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Hondarider68
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Hondarider68 4/29/2023 9:12am
4/29/2023 9:12am

just wanted to say thank you to DynoDan22  and Last2Stroke. Got my bike backed together no air leaks at all 

 Thank you both

  

4
GoggleFiend904 4/29/2023 10:59am
4/29/2023 10:59am Edited Date/Time 4/29/2023 11:00am

Just wanted to throw this out there, I had a very slight leak in my right side seal and it wore my piston/rings on the bridge area (common problem from leaking seal), so keep a lookout for a slight loss in compression. 
 

I was chasing that issue thinking it was bridge clearance, currently running a pretty tight clearance with a wossner piston and new crank seal, all has been good 

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Hondarider68
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Hondarider68 5/13/2023 8:20am
5/13/2023 8:20am Edited Date/Time 5/13/2023 8:21am
GoggleFiend904 wrote:
Just wanted to throw this out there, I had a very slight leak in my right side seal and it wore my piston/rings on the bridge...

Just wanted to throw this out there, I had a very slight leak in my right side seal and it wore my piston/rings on the bridge area (common problem from leaking seal), so keep a lookout for a slight loss in compression. 
 

I was chasing that issue thinking it was bridge clearance, currently running a pretty tight clearance with a wossner piston and new crank seal, all has been good 

thank you, I will.

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