Is this air leakage normal?

[crashcourse]

I have been working on this top end rebuild for months (making time for it has been hard), but I'm nearly there. Before I rivet the cam chain together, I want to know if this is a normal amount of air leakage (you can hear the hissing of air as I turn the crank):

I am turning the crank with a wrench. The rockers are not installed so the (freshly lapped) valves should all be closed. Is the air leaking past the (new) rings? Are my (new) gaskets not sealing? Did I do the valves wrong? Will this go away? I have never rebuilt an engine so I have no yardstick for what is normal.

Do I need to go back a few steps and fix or check anything? I really don't want to tear this down again for a very long time.

Thanks!

 

[Bob Kelly III]

First off the cylinders are fairly dry without the oil circulating and You can hear air excaping when it's trying to be compressed
the question is is it too much or not ? who knows !!!!! I doubt it !
it's normal to hear that when the valves arn't being opened..... continue putting it together and once you fire it up remember to retorque the head !
.... that's my opinion
I could hear air excaping in my engine when I turned it over it's nothing to be worried about....
Bob........

 

[retiredgentleman]

Completely normal. If you re-built the top end according to the Yamaha Service Manual.............piston/cylinder clearance, valve guide wear, piston rings installed correctly, new valve stem seals, valves lapped etc. etc. , you have nothing to worry about.
The people that don't pay attention to the specifications, in the service manual, are the ones that need to worry.

 

[crashcourse]

Good to know guys, thanks!