Sudden nasty oil leak. Ideas?

#1
Put about 2 hours worth of short blasts over a month or so on my bike with no leaks. All of a sudden I’m flingint oil all over behind the pull cord area. Assumed it was the main seal so I popped the flywheel off and that seal looked great. Crank seals look good on both sides. Is the governor hole pictured here an area that could suddenly start leaking? Only real change I made was a 160 head and Changed from unknown oil the engine came with to a 0w20 mobile 1 synthetic.

Top gov rod has been removed and is plugged tight. I see no case cracks. Is this gov “through” area a leaking point? Can I just ruff it up and JB weld over it if so?

I’m out of ideas. Didn’t think it’s be hard to diagnose. Seems to only happen when crank case pressure is built up. I have an open hose on the VC with a filter on it. It does not appear to be plugged at all. Very little oil coming from it.

Any other ideas?

Thanks! leak.JPG
 
#2
ok would help if I read simple instructions. The governor removal video I used did not mention this pin or it's removal.

Clearly this needs plugged. Just curious why it ran for several hours without leaking... and now it leaks.
 
#3
You actually do not need to remove it. its pressed in and if you like you can use a punch to punch it into the crankcase then remove it from the inside and then tap and screw in the proper size setscrew. If you changed the head did you change the venting? can you tell where oil is coming from?
 
#4
appears to be coming from behind flywheel and flung it everywhere. Was dripping out of pull cord area. Got it all wiped down. And seals look mint. I did pick up new seals, and it never leaked before. Guessing it is coming out of that dowel area.

I did not change the venting setup. The only vent is on the valve cover. It’s an open tube with a filter on it. I blew through it seems fine. DO you need to change the venting system when you throw a 160 head on? The VC is the same.

thanks!
 
#5
No changing the head should not change venting if you are still using the same valvecover. If the vent were somehow blocked it will blow oil out the seals. You may want to verify the one way valve is ok in the valvecover. Do you happen to have a small handpump to pressurize the crankcase to about 5 psi and see if you can find the leak.
 
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