B31 timing chest air pressure valve.

[Janacek]

A rather unusual question.
What should be the pressure in the timing chest be for the valve to release the air pressure.
Bike has started smoking (again) and last time it was a blocked oil pressure release
ball and spring.Cleared it with a length of strimmer chord and all was well.
 This time clearing the oil pressure valve didn't stop the smoking.
The problem this time is a seized air pressure release valve and try as I might,I can't undo the screw that holds the disc valve in place,even with an overnight soak with Plusgas and the biggest screwdriver I've got.
I've given the disc valve a light tap with a small drift and by using a little hand pump with a built in pressure gauge,I can now get air bubblés coming through,but the pressure gauge indicates 20psi.
This sounds too high to me,and I would have thought 5 or 6psi would be enough.
Anyone know what the pressure should be for the disc valve to release the reassure in the timing chest.

[Derek996]

There is no pressure required to open the air release valve. It is meant to allow air through on the piston downstroke and the vacuum created as the piston moves up again pulls the disc up closing the vent. The idea is that this will create a partial vacuum inside the engine helping to prevent oil leaks. Obviously not very successfully most of the time.
If it gets gummed up as yours seems to be it will create excess crankcase pressure. You should be able to dismantle it and clean it. I'm guessing that the air release adaptor screw (106 in the attached pic) is seized in. If you can't get it apart new parts are available from Draganfly for not much money

[Janacek]

Thanks for the reply Derek,Draganfly do have the parts,and I was on the point of ordering but no bike has defeated me yet,so I had another go at loosening the screw holding the clack valve (I think that's the right name) warmed it up with a gas torch and it finally gave up.
It had a considerable amount of what appeared to be black grit inside,and after a good clean I re-assembled it.Fully tightening the screw holding the valve resulted in no air going either way through the valve.Loosening it a quarter turn and using my pump air would go through easily from inside to out,and there was resistance from outside to in,so I left it at that.
Started it up and no smoking!
Still a list of jobs to do.Fork bushes,steering head bearings,kickstart quadrant,clutch and I still haven't fixed the erratic tickover.Having done everything I can think of checking ignition,air leaks,jetting etc,the only thing left could be a worn throttle slide.
The work is endless innit?