Wonder if anyone can explain this.
I had a front cct let go, so stripped the fairings etc. and took of front valve cover. Sure enough cct had let go and the camchain was climbing the exhaust cam sprocket. I then took the cams out.
To establish whether I had any valve damage I inserted a tube into the spark plug hole and sealed it to prevent air escaping back past the tube. I then removed the exhaust pipe from the exhaust port.
I then blew cigarette smoke down the tube into the combustion chamber and it came pouring out the exhaust port. Sh*t I thought, exhaust valves bent. Logic being, cams out, therefore valves closed, smoke getting past valves = bent valves.
Took carbs off and removed the head and guess what? The valves are all fine.
I poured some petrol ino the exhaust manifold with the head sitting upright, ie. so a pool of petrol sitting on top of the exhaust valves, not a drop seeped through. Then applied compressed air into the exhaust manifold with a seal around the air hose, ie, pressurised the port between the valves and the exhaust manifold with the pool of petrol still there and none was forced past the valves.
I am completely unable to explain this. Any ideas?
PS: Many thx to Del and Pete for their excellent assistance.
Thx
Ed