Valve Problems Z900

I have a problem... I have dropped in some new valve shims, several times now in the last couple of weeks. Seems that the shims on cylinders two and three on the exhaust side keep getting too much clearance. This time it happened within a day, installed them last night and tonight i am going to have to put in bigger shims in order to get it back to where it needs to be. I am checking clearance when engine is completely cool and i have even resorted to turning the engine over a couple of times and checking again, fine at this point. After the bike is ridden the clearance is out of tolerance again!
Please help.

I am thinking possibly a bent valve or broken/worn spring. Cam is torqued to spec.

Thanks

yeah id say something is weird,have you run a compression test?

yeah i have and compression is not an issue. im soooooooooo confused:( :S :huh:

More likely how you measure the clearance than the clearance changing. See the "Valve Clearances" article on our website under "wg's Tech Stuff Index". There are marks on the cam sprocket for alignment when you check clearances. I suspect that you need to get those marks aligned in order to make consistent measurements. Don't see the valve springs as an issue... it doesn't take that much to close a valve with the lobe off the bucket/shim.

the only reason you would be getting more clearance so fast is if either the top of the valve stem is failing or the contact spot on the bucket, remove the bucket and inspect both of those areas