Strange Noise (Again)

[Spitfire]

OK, now I have done my homework and looked at what you've already got on the site about this sort of thing. But, pretty please, I've just had my carbs balanced (bike kept stalling at the lights, no matter what the idle speed) and now, yes, the bike runs like never before, but a couple of minutes into the ride, when you're stationary, there's a noise like someone tapping the engine case with a key. It's quite loud, but only comes once the bike's been run a bit. In previous despatches someone said it could be 'cam float'. Just tell me it's not the cam chain tensioner about to die on me as I hit 90 mph! I would ask my local garage to have a listen, but on the phone they seemed eager to do lots of work before even hearing it!! Funnily enough, after a long (60 miles) fast ride the other day the noise seemed to go away. But it's back now. If it is the tensioner and it goes at three figure speeds am I going to die?

[sprint_9]

Take your tensioner out and check it, its worth a shot.  But Im going to bet that it is the cam sideplay delema that many of our bikes have, including mine.  What you describe sounds very similar to what I have experienced.

[Spitfire]

Cheers bud. But, now don't laugh cos I just ride the damn thing, but what exactly am I looking for when I take it out? Also, say I just leave it and it does go, what's the outcome at speed?

[scratch]

If the cam chain tensioner fails, the resulting slack will cause the intake and exhaust valves to open later, so on the exhaust stroke the piston will come up and smack the exhaust valve, bending it and you'll lose all compression. Subsequent strokes will hammer the bent valve into the valve seat; maybe break off the valve and bang it around inside the cylinder, damaging the sparkplug, intake valve and seat, piston head, cylinder walls; all kinds of fun.

[sprint_9]

I dont exactly remember what you are looking for when you take it out.    I also am going to check mine cause I have the engine out of the frame.  So if anyone knows the procedure for checking our tensioners now is the time to chime in.

[Von Vester]

Before you take anything apart I would listen to your engine with a long screw driver. Hold the end of the handle to your ear and touch the tip of the screw driver to the engine, sort of like a stethescope. Touch the engine in different places and find out where the tapping is loudest. That is where your problem is.

My GS has had that tapping sound ever since I got it. 10,000 miles later, no problems. On my motorcycle the sound is coming from the tachometer drive pinion.

If you solve the mystery on your bike please post it. This is a very common complaint with folks who are riding the bike for the first time.

[scratch]

It is an air-cooled motor, hence noisy. But, by no means does this mean to discount what you're hearing as dismissive, you may learn something tracking down this 'noise'.