GS750 Engine knock

[Guest]

Hey guys I recently bought a 1983 GS750 project. When I bought it the bike had a sporadic "tinging" noise coming from the engine, which the seller advised me was due to the cam chain tensioner needing to be replaced. I bought a new cam chain tensioner and replaced it. The sporadic "tinging" noise is gone but now there is a consistent knock which increases as the rpm's rise. To me it sounds like its coming from the top end? I'm assuming that I screwed something up while installing the sam chain tensioner but am not sure. Any advice would be greatly appreciated. Thanks guys.

[Pb9717]

Rocker arms/ valves out of adjustment. Take off the valve cover and look around. Check the gaps. I just repaired a similar issue, and the valve spacing was WAY outta whack. Now....alls good. You'll need tappet tools. (83' has no shims.) and new valve cover gasket.

[steve murdoch]

Welcome to the site, cw.
Here is an excellent thread from bwinger on a tensioner install.
Hopefully yours went something like this?

http://www.bwringer.com/gs/camchaintens.html

[cwneal]

My install went like that minus setting the engine to TDC.... could that be where my problem lies? If so what is the procedure to correct this? Is it valve adjustment like pb9717 suggested? Thanks

[tom203]

Since you had camchain tensioner issue, chain could have slipped a tooth on a camshaft.. best to check and know for sure that all is well. Have a look here for finding tdc

http://www.bwringer.com/gs

[cwneal]

How do I check if the chain slipped? Am I removing the tensioner, finding TDC and reinstalling it?

[londonboards]

Be careful. Don't jump to conclusions. You can easily check the cam timing ( to see if it has slipped ) just by taking off the cam cover and following the instructions in the manual.

A cam chain would have to be seriously loose to jump a tooth. And most likely the bike would not run at all well - if indeed it hadn't banged the valves into a piston already.

Let's just assume that it isn't that for a moment. You described a "consistent knock". Well I've never heard a cam chain knocking.

Knocking sounds more like cam end float ( no problem ), bad big ends or little ends ( very serious ) or some sort of clutch noise ( not terminal ).

Run the bike with the oil filler cap off and see if that is where the noise is coming from. That would be a clutch noise.

If that isn't it, get a piece of wood, put it to your ear bone and go around the engine placing it on different areas to see if you can work out exactly where the noise comes from. That will give us a better idea.

Try to take a video with the camera microphone right up against the engine ( at various different points ), upload it to YouTube and let us hear it. Don't worry about the video quality, it is the sound you are after capturing.

Here's a couple of videos that have a knocking sound from the engine.

Let's hear yours.

Take it from there.

Greetings

[cwneal]

Thanks a lot! I will get some videos up this weekend

[tom203]

A cam chain would have to be seriously loose to jump a tooth. And most likely the bike would not run at all well - if indeed it hadn't banged the valves into a piston already.

A few years back, I recall a guy who found that his chain jumped (or was misinstalled) one tooth on exhaust camshaft - it didn't impact piston, but he had poor performance. Anytime you have a tensioner issue, best to confirm the cam timing is still good.

[cwneal]

Ok here's a quick video of the noise I'm getting. Let me know what you guys think!

[londonboards]

You've got 2 bad sounding noises there.

Firstly, there is a knocking and secondly there is the swishing/tinkling sound when you rev up.

You've gotta start with that cam chain.

Then find out where that knocking is coming from.

Greetings