Knocking noise at idle

[azr]

Hey all. The saga continues. 79' GS850G. Battery went dead but that's probably not the worst part. At idle, it's running rough (I've already gotten some good advise about what to rebuild for that problem), but at idle I can hear a knocking coming from the engine. Each time it does this knock it seems to effect the idle, idle will momentarily drop and come back up, very quickly. I'm planning of pulling the carb and doing the rings and boots, but I'm concerned about this knocking noise. The noise isn't there until the bike is driven for a good 20-30 mins. I can't hear it when I'm riding only when I'm idling, and it's not a constant knock, it's speratic, every couple seconds, then waits 5 secs then another one, or two, or three. Hope that explains it enough. Appreciate any advice.

[salty_monk]

Have you checked the valves yet?

Have you opened up the clutch at all? The clutches are renowned for being noisy.
Does it have stock ignition or aftermarket, even the stock has some small timing adjustment available.
It sounds like it "could" be a missfire as that would certainly affect the idle. Depending on what's causing it then it could well be sporadic. It could be as simple as a partially blocked pilot jet leading to fuel starvation for example. Very likely if your idle is rough anyway. It should idle comfortably at 1050rpm.

Check out the plugs & wires too as well as taking a look at the coils. Make sure you have a nice "fat" blue spark coming from each plug in turn when you crank the bike over.

Sounds like you need to do a full service on this bike, carbs, valves etc. Chances are the noise will go away when you do.

How about a "you tube" of the bike making the noise, might help diagnose it...

Read the "stator pages" concerning the dead battery. If you are lucky you may only have to add an extra ground wire from the RR direct to the battery.

Dan

[SqDancerLynn1]

Can't say much more than already said by Salty

[Nessism]

I agree with the salty one, it's pretty pointless trying to diagnose a noise when the basic maintenance is not done. Clean the carbs and install new O-rings, new O-rings on the intake boot, seal the airbox if the foam is deteriorated, clean the air filter, adjust the valves, sync the carbs, and tweak the mixture screws until the bike runs properly. After all this stuff is done, judge the noise.

Good luck.

[Dave8338]

Cam float?