Hi everyone!

I very much appreciate all of the advice in advance!

I have a 1989 XT600 kick start version with 37,000 miles on the clock. This is unreal for any bike! Motor has never been opened up.. unreal.. owner changed the oil every 2K miles, was very easy on the bike and never took it off road. Bike has great compression and runs like a clock... starts easy and has plenty of power... I would say that this bike is MUCH more reliable than the Honda Xl600 ...

The main work I did to the engine was to replace the left/right case gaskets as they were seeping... I also had to helicoil the oil filter cover screw as it was strpped... the engine was VERY clean inside from all the oil changes. No signs of any 5th gear chips or particles. I also changed the carb insulators, and all new oil seals.

Main issue I have is I have oil leaking out of the main shaft seal only at high RPM 75 MPH or more riding. if I just keep it in city streets no leaks. I did put in a new seal and it was leaking... thinking the new seal was bad.. I have had this happen in the past.... I put in another new seal... same thing leaking. Oil is all over the tire and runs down the swing arm.

Any ideas out there? I have never seen this happen and I have owned over 140 bikes in my days. I made sure the seal was installed level and flush with the case.

By the way.... the YSS shock for the XT600 is just FANTASTIC!!!! SO HAPPY with the performance... on a fast trail ride the control is just amazing. I also modified the front forks by welding 2 out of the 4 holes in the dampening rod shut. Then you add the progressive springs and you are set... no bottoming with about 5 lbs of air in each fork.

Thanks for the help!!!

Since it only leaks at high RPM, it's probably caused by crankcase pressure.
Have you checked the engine breather for any restriction?
Are you using genuine oil seals?

Bob

__________________
Remember that Assumption is the mother of all f**k-ups.

Thanks Bob!!!

Yes... using OEM shaft seal... I'm going to check the breather to make sure it is clear... that has to be it!!!

Another question...the bike runs to good yet I feel as if I should replace the valve seals. I have read here that oil will leak past the stem and cause carbon build up into the combustion chamber scoring the cylinder wall.

There is no smoke at start up at all yet I'm sure after 26 years and 37K miles it should be done..

What do you think?

thanks! Eric

Here is a shot of the bike after a good clean up and light restoration.. she was in great shape as always garaged.

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Nice bike
If there is no smoke on start-up then your valve seals are good. No point in replacing them.

Bob

__________________
Remember that Assumption is the mother of all f**k-ups.

Thanks Bob!

That was the issue! The new YSS shock has the spring set higher in the shock structure where the breather hose connects to the air box. It partially restricts it when you sit on the bike as the spring compresses. When you take the bike off road and hit impacts the spring was closing the vent line fully causing oil to purge out of the main seal.

Problem solved and thanks again!

Eric

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140 bikes, and impressed by 37.000miles on a bike? You need to cover more miles on a single bike, haha.

I've seen 2-strokes go further without beeing opened.


Glad you got the bike sorted, it looks mint!. Keep and eye out for the leak, usually the seals can/will keep seeping a bit, once they've started to, whatever the reason was.

Hi Esacco. I'm interested on that shock. Please, Can you share the yss code? I Need another help. Can you measure the stroke of the shock? Thanks a lot. Nice bike.

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