Terrible sounding slapping noise above 2K

[jonathan_whitwell]

The bike: 82 GS750e, 66k miles
The problem: I had my cam chain tensioner locked in a pretty tight position. I took an 80 mile trip on the highway, and it gradually started making a really loud slapping noise, and lacked power. I brought it home, took off the valve cover, and the chain was pretty loose (1/4 inch free play up and down between the two cam gears). So I properly installed the tensioner, which made the chain seem much tighter when I tried to wiggle it with my fingers. I checked to make sure it was operating properly by rotating the crank and the knob on the side of the tensioner counter clockwise, and then rotating the crank clockwise slowly. The knob on the tensioner spun forward, which indicated the tensioner took up all the slack. So I put the bike back together, started it, and it sounds fine at idle, but when I give it any throttle at all there is a terrible, loud slapping noise. It sounds like the cam chain violently whacking something. When I had the valve cover off I tried to look and see how the plastic guides were doing. The only thing I could see like that was the very top of the guide that goes down the front of the engine, and it looked intact (I kinda forgot to check out the plastic guard on the bottom of the valve cover).
If it jumped a tooth in timing, wouldn't it make the noise at all RPM's? I'm going to go take it apart again and check the timing while I wait for someone much wiser in the ways of GS motorcycles to take a stab at this problem. Thanks guys.

[jonathan_whitwell]

update

I checked the cam timing, there's 20 pins between the marks, as per the clymer manual. The plastic guides look fine, although there is a little bit of wear on the valve cover right in front of that guide. Still totally stumped, I have no idea what could be making this racket. Any ideas will be appreciated and investigated.

[t3rmin]

Are the cams aligned with the crank? Maybe they're aligned with themselves but not the crank. If so, the noise you're hearing is probably valves hitting pistons...

But that sound wouldn't go away depending on RPMs I don't think...

Maybe the chain is badly stretched? Did you measure the distance between the 20 pins?

[mark]

I was thinking valves as well. At least a possibility.

I'd turn your crank and check the full length of the cam chain for possible damage or stretched links. Check your cam idler for damage as well.

[feelergaugephil]

66k!!!!!!!!!!!!
Time to change your camchain mate, you can actually buy the soft link ones from UK for about $35, and yes they are safe to use, I have used them on 3 GS1000's, and the big plus......... you don't have to split your engine.

Did it go quieter when you manually tightened the camchain adjuster?
if so, replace the camchain, its WORE OUT.

[chef1366]

The valve guides also need replaced which requires you to plull the head.