do it yourself if you can, or at least do a quality check

There was a bike shop close to me in centurion run by chap called Martin, I think he had a fair reputation of doing reasonably quality work.
Martin had a very nice R90s on his shopfloor, obviously maintained by himself.
This had put some notion in my head that Martin must know what he is doing and I subsequently took my motor to him to have hardened valve seats put in.
While he was tending to this I would organise the frame and tank painting, cleaning and painting smaller parts etc.

Bike eventually assembled and I did about 3000km since rebuild. Right cylinder was sweating from the base so bought all the new o-rings to replace to fix the leak.
I noted there was not a lot of oil in the tappet cover when i removed the tappet cover. I ran the starter motor and saw that no oil was feeding to the intake valve.

Those that know these motors will already know that he had installed the rocker shaft the wrong way around.
It does not look like there has been damage on the shaft and bearings, lucky I had it open and after swapping the shaft around, oil feed is good.

Overinspect the work people do for you. removing tappet covers and checking oil feed is a good start on any engine work.