Removing cylinder head

So it ran for a period after the event, albeit very poorly?

Since the tensioner is well over the 16mm drop, I wonder is that enough to let the chain jump teeth.
Could you try set timing again, put the spacer into the tensioner, and assuming it turns over (by hand initially) ok, see if compression returns and it runs ok?
Before taking the head off.
 
So it ran for a period after the event, albeit very poorly?

Since the tensioner is well over the 16mm drop, I wonder is that enough to let the chain jump teeth.
Could you try set timing again, put the spacer into the tensioner, and assuming it turns over (by hand initially) ok, see if compression returns and it runs ok?
Before taking the head off.
If checking compression, only take out one plug per cyl., and tie throttle wide open.
 
That's my suggestion, unfortunately.
Measured no compression at all. Tensioner measured fine, but I'll redo and post numbers. Bike did less than 20K km.
I have to verify a third time, but this is the timing at TDC:
IMG_20210423_134938.jpg IMG_20210423_134943.jpg
Why do his cam gear bolts look like that ? Mine have button heads. In the picture it looks like the lower bolt on the far gear is backing out.
 
So it ran for a period after the event, albeit very poorly?

It ran just normal, AFAICT, just 90 km/h hill down when it went out.

Since the tensioner is well over the 16mm drop, I wonder is that enough to let the chain jump teeth.
Could you try set timing again, put the spacer into the tensioner, and assuming it turns over (by hand initially) ok, see if compression returns and it runs ok?
Before taking the head off.

I can breath through the cylinder with valves "closed".
 
It ran just normal, AFAICT, just 90 km/h hill down when it went out.



I can breath through the cylinder with valves "closed".
If you can breath through the cylinder with valves closed, that sounds like a major malfunction! If you blow into the cylinder through the spark plug hole where does the air go? Can you hear it escaping through the throttle bodies? Exhaust? Crankcase breather? That would help narrow down the problem.
 
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