Knocking

Mine knocks a bit as well Nick, it'll be the clutch basket damper springs in the back of the basket they lose tension and the basket moves back and forth making a knocking noise which gets quieter when the engine is hot.
My cb 500 sounds terrible when its cold, its a known problem and as you say when you pull the clutch in it shut ,em up.
Its a common prob on the cb 500s, nearly every one of them does it.
One way of quietening them down is to put a suitably sized washer between the spring and the housing and weld it in to take up the slack.
I have done spare basket for the 500 but haven't fitted it yet as the play doesn't bother the engine ,it just annoys the rider.lol

There's a few threads now on the dreaded "Honda Clutch Rumble"! Here's my take on it, as I've been this way with the CB900FA clutch which is identical. Or so I thought- see below....

Dave- the CB500 must have springs in the backplate- similar to a car clutch plate? Other Honda's including SD's and the 750/900DOHC's seem to have rubber dampers similar to the arrangement on the back wheel. The big Honda's suffer terribly with this rumble. Rather than wear and go hard like the rear wheel hub, the rubbers in the clutch back plate assembly go soft and shrink- years of engine heat and oil I guess. There never seems to be metal-to-metal contact, but especially in tick-over it makes the clutch outer bounce around and make it all rattle. First indication is marking and grooving of the outer basket finger slots- the inner slots seem to stand up better.

When you have your clutch outer on the bench, you should only have a very slight movement of the ring gear in and out- as it is trapped by the rivetted ring. Any clearance is just to allow the ring gear and clutch basket to move independently with flexing of the rubbers. And if you test the rotational play it should be minimal- basically you are compressing the rubbers and if there is any play you will get rumble! On another thread someone said they had half a mil or so of play which sounds worn to me.

Trouble is, the clutch backplate is not a user servicable part and I don't think Honda ever made the rubbers available separately. It's all rivetted together, so the best and easiest fix is a new backplate. You can replace the clutch plates all you want- it won't change a thing. The backplates for the 750/900DOHC's are NLA- probably used up over the years fixing the problem. But a Dutch guy has produced a kit of new rubbers and a set of bolts- basically you drill the rivets out, replace the rubbers and bolt it back together. I have a kit here ready for my CB900.

But the rubbers are different on the SD's and I don't know anyone who does a similar kit. So the best option for SD's remains sourcing a NOS backplate or better clutch. For reference here is one plate I stripped down and the plan with this assembly was to see if I could fit the readily available 750/900 rubbers and bolt it back together...


The back of the plate with the heads of the rivets holding the circular keeper plate on:-





You centre-pop the rivets and drill the heads off- 3 done already here:-





When all the rivet heads are off, the keeper plate just lifts off, the ring gear then comes off and there are your rubbers! This is where my plan fell apart- as they are clearly different in size and shape to the 750/900 clutch rubbers:-





If only someone did sets of these for our bikes:-

On the old forum a Dutch guy was going to lazer cut some new SD clutch rubbers for me as a guinea pig . I drill out the rivets and tapped the holes M5 .

I never got the new rubbers so put the clutch back together using loctite on the screws


Paul ,what's the name of the chap who makes them for the bigger machines ?