Sticking valve...?

[Alan G]

I am very confused... My VH500 iron head twin port on a 1958 bottom end doesn't play nice.

Kicking it over sometimes feels like there is no compression, then suddenly there is compression and all is well. I have disconnected the valve lifter cable, but that didn't fix it. Kicking over with a compression gauge connected it is showing about 45psi. But as I say it feels like there is no compression when kicking so that is not a surprise.

I am new to these things..... so.... Is it possible that a valve is not reliably sealing at low revs. Is this a symptom of a bent valve or other such things from a previous life? It is the 'intermittent' problem that gets me confused.

Thoughts:
Sticky valve
Movement on rocker
Sticking pushrod
Movement on cam followers
Uneven cams
Movement on cams

First I'll loosen off the tappets and see if compression stays up - narrows it down to sticky valves or something deeper.

Just wondering if anyone has seen similar? What is easiest to check off?

[adrie.degraaff]

There has been a batch of new exhaust valves made of wrong material, they deform (melt), put an old valve in and the problem is solved.

[tony.barnett]

Could just be a bit of carbon under the valve head. But...if you want certainty then whip the head off and take a look.

[Alan G]

Spoke to a few people today, and this does not seem to be as uncommon as I thought. So... I'll just run it as is and see what happens.