GS 450 engine noise

[JTsGS650]

Hi all, I need some suggestions and perhaps some advice about my 450 project. > http://www.thegsresources.com/_forum...d.php?t=138228

Long story short is I got the bike together and when I turned her over with the starter, there was a clack-clack, clack-clack, clack-clacking from the top end. This weekend I pulled the valve cover and turned the motor over by hand to see if I could see anything out of the ordinary. The motor was still making the clacking noise as I turned it over by hand, just slower. But nothing looked out of the ordinary. So I pulled the cylinder head to see if anything was out of whack. Everything looks fine. The pistons were moving up and down and the cylinders looked fine, the valves looked okay but I didn't remove them from the head. There was nothing broken and nothing obvious. After I removed the head, I turned the motor over again by hand to see if the bottom end was perhaps making the noise and it seemed fine with no noise. I know it's difficult to diagnose an engine noise without hearing it, but I'm looking for some suggestions as to what is making this noise and what to look for, so I can get this thing up and running. Thanks in advance.

John

[TheCafeKid]

You play with the pistons at all?? Grab em and yank. if they move up and down, you've lost a con rod bearing, but usually you cant hear it when turning it by hand..

[atchbo]

Maybe keep an eye out for cam chain tensioning too... either the tensioner, or the plastic guides or the idler sprocket or the wrong number of links between cams. When I reassembled my GS400, at one point the cams kept spinning beyond the chain and then were re-tensioned when the chain caught up. I noticed before starting the engine, so I don't know what it sounds like, but this could be part of your issue. Check everything and turn the crank by hand until you are satisfied that it's good, or else you could bend a valve against a piston. My 2c.

[JTsGS650]

These are good keep 'em coming.

[JTsGS650]

You play with the pistons at all?? Grab em and yank. if they move up and down, you've lost a con rod bearing, but usually you cant hear it when turning it by hand..

Play with my pistons, tee-hee . Seriously though. I have not grabbed the pistons and yanked them. I've only taken the head off not the jugs. I did push down on them though and there was no movement. The sound I heard is a pretty loud 'clacking'. And as you mentioned, I wouldn't expect to be able to hear a bad bearing like that.

Maybe keep an eye out for cam chain tensioning too... either the tensioner, or the plastic guides or the idler sprocket or the wrong number of links between cams. When I reassembled my GS400, at one point the cams kept spinning beyond the chain and then were re-tensioned when the chain caught up. I noticed before starting the engine, so I don't know what it sounds like, but this could be part of your issue. Check everything and turn the crank by hand until you are satisfied that it's good, or else you could bend a valve against a piston. My 2c.

After doing a little searching on 'engine noise', I did see a post regarding cam chain tensioning, I did pull and reset the cam-chain tensioner but the noise was still there. I also might add that when I pulled the valve cover and head that motor looked like it hadn't been apart before.

For some reason, I think it has something to do with the valves. The sound that it was making was like some tension was building and then it was all of a sudden released like a spring. But I don't have a tool to remove the valves/springs.

Any other ideas?

[JTsGS650]

Bumpity...

[TheCafeKid]

Snapped valve spring.?? You can make a valve spring compressor out of a C clamp and PVC....Basscliff's site has a tutorial Steve did on doing just that, video style... Very good stuff.

[JTsGS650]

I just watched Steves video on removing/installing valves. Good stuff. I guess I'll give that a shot this weekend. Although If there was a snapped valve spring I would expect the valves to be loose? I'm almost tempted to put it back together and see if the problem fixed itself. I love it when that happens!