Valves stuck/popping?

[Guest]

Just recently picked up a 1979 gs1000 and got it to start the other day and idled for a few minutes. Tried starting today and nothing. Then heard a pop while trying to start. Took off the exhaust and looked into the exhaust ports and turn the motor over by hand. Those valves go down but when they are ready to come up, they "pop" up like they were stuck and I believe that is the clank/pop noise I'm hearing. Very clear its coming from that when I turn it by hand. Tried googling it and found nothing.

[GregT]

If one or more valves were stuck due to long storage, you may well have bent one. Not uncommon on OHC motors - old Jaguars are very prone to doing it.
A check of the valve clearances should show it up.

[gustovh]

Lack of lubrication, maybe.

V

[tom203]

Remove the cam cover and lube all the buckets up - these are the gizmos that cam lobes push down on..and valve springs return to closed position. One or more buckets might just be stuck. Remove spark plugs and rotate motor by hand and observe bucket action..

[Tecmo89]

Update!

So I took of the top cover to inspect and I turn the motor over by hand and the chain seem fine except when the "pop" happens and then the chain is loose. Would this help solve the issue or give us an idea? Attached an image of it being "loose" when the pop happens.

[Big T]

If your cam chain is loose. you might have a broken chain guide. First check the tensioner to see if it's working
Also, confirm the cam timing, because with a chain that loose, it's probably skipping over the cam gear teeth

[Tecmo89]

Update #2

Cam timing tensioner definitely bad, have new used one now that is good. Timing was way off with cams/sprockets. Set timing correctly per service manual, see attached picture.

[tom203]

How is the condition of rear chain guide?

Here's another view of cam to crank timing with crank at tdc mark. double check your work!


image.jpg