1983 GS450GA Compression Issue

[GeminiUnknown]

Hi guys,
I picked up a 1983 GS450GA a couple monthis ago off of Craigslist. The previous owner had bought it eight years ago from a guy who had taken apart the top end to fix something. I put everything back together but when I take compression readings I get 50 in the left and 70 in the right. I can't turn any of the tappet buckets by hand. Do I just need different shims or is the low compression from something else?
Thanks!

 

[fastbysuzuki]

When you say "I put everything back together" are you saying that the head was off when you purchased it?
If you cannot turn the buckets when the cams are in the correct position then the valves could be being held open or worse some burned which would require the head taking off and the valves checked/replaced possibly the seats recut and valves lapped in.
But first you will have to re-shim all the valves to the correct clearance then run it and recheck your compression and go from there.
Being you live in the USA you are able to use the shim club run by a member here where you contact him with the sizes you require he will send them to you and you return to him the shims that you take out.
For the shims PM http://www.thegsresources.com/_forum/member.php?478-Ghostgs1

 

[hockey911]

If you cant spin the buckets that could be a problem. Get yourself a feeler gauge set from autozone and check the clearance.

Yes it can make a huge difference. If the shim is to big it will cause the valves to stay open, there are shim kits on ebay for this bike, or you could polish your old ones down until they fit. (I dont recall off the top of my head what clearance you should have for the valve lash, but its a google search away)

 

[Guest]

I agree with the other comments. If the cam lobe is not engaging the shim and the bucket does not turn, the shim is too thick!