79 gl1000 engine knock above 3000 rpm

[dasmith01981]

I just baught a 79 GL 1000 and it seems to have a knock at 3000 rpm and above but only under a load does any one have any ideas

[dasmith01981]

I have checked the timing belts and they are good I've gone through the carbs,checked the coils, plugs, and wires,I've also adjusted the valves to proper specs and checked that the rocker arms are not hitting the valve covers

[virgilmobile]

Stick a compact mirror in the plenum box with a stiff wire at a angle.Using a flashlight,eyeball the slides,rap the throttle and verify each slide is jumping up.My 83.1100 sounded bad at that rpm,one slide was stuck down.Really messed up the fuel balance and it rattled in that range.
At least it's a easy look.
Also,a swollen inner thermal liner in the header can restrict exhaust flow and make it sound like it's knocking.
Yes it has a liner inside the header pipe,and it's not steel.
Rare, but it did happen to me on my 78.It was swollen almost shut about a inch or so below the mount.

[jurkiel]

I have the same problem in my 1977 GL 1000,
I've changed engine oil few days ago ( I put Motul 10W40) , and I'm almost sure there was NO NOISE before that so maybe it is an oil ?
I didnot check that yet but I start from the oil