Rattle at idle on left side

[ron2830]

I have noticed this before but never thought to ask about it, kind of a rattle on the left side at idle, kind of random, not a regular beat to it, seems to lessen a little with the clutch disengaged and no noise under load at higher rpms, so I don't think it is a bearing or piston slap.

[DiverRay]

It's probably the vacum advance under the left cover. If you take the cover off, you will see the vacum line going into the actuator. I would lube all the piviot points, and verify the vacum line from the actuator is routed to the #2 CARB BODY, not the #2 intake manifold.
Ray

[ron2830]

Thanks this is definitely where the noise is, can hear it clearly with the cover removed, do I need to remove the assembly to lube, the Clymer manual makes it seem that you do need to remove it. I can't see the pivot points or maybe I am looking at the wrong thing.

[DiverRay]

I just used a CRC greaseless lube on mine.
The big rattle is if the vacum is on the manifolt (rubber boot between carb and engine) instead of the port on #2 carb. The port is designed for the advance unit, and has a small opening inside to keep the advance from rattling.
I think if you doi a search on "carbs", or look at the "Tech Tips", there may be a picture.
Ray

[ron2830]

Thanks, it was on the manifold when I bought the bike, but I caught this early on and moved it to the port on the carb. So I don't need to remove the mechanism, just spray it with the cover off? I got the impression from the clymer manual that the part that needs to be lubed requires removal of the assembly, it seems to show that after you take the timing plate off, you remove the screws that allow for adjustment of timing to pull it off the engine case.

[DiverRay]

With the CRC, you should not have to pull anything. If you are going to use a moly grease, or synthetic grease, you will have to pull it apart to grease things.
The grease will also attract dirt, and cause more wear. That is the reason I use the CRC "greaseless" lube.
Ray

[ron2830]

I may be missing something here but from looking at the parts diagrams it appears the parts (weights and pivot points) that need to be lubed are on the other side of the casing that mount the vacuum advance mech. How do you get the lube in there without taking it off? Thanks again.

[DiverRay]

If your parts are really dry, you will probably have to take it apart. I would try to use a "dry lube" that does not suck all the dust in.
Ray

[ron2830]

Took it apart, was not that difficult, just needed to check the timing again when I was done. Lubed it up and the rattling seemed to lessen but now is back. Definitely the advance mechanism. The springs seem strong enough when I rotate the reluctor to its limit. I did not take the reluctor off the shaft, having some trouble with the c clip (need another tool). Any other thoughts?

As long as it does not damage anything I guess it is OK, just kind of bugs me.

[randy]

Ron,

Just one thought.

When you remove the reluctor from the shaft, make sure you put it back the same way or your timing will be out by 180 degrees. Don't ask me how I know that!

[ron2830]

Thanks Randy, I usually mark things when I take them apart but did not think of it for this. I have been there done that also with different parts!

[underdog57]

Vacuum advance rattle

Mine does this too .
I have not adjusted the carbs after a rebuild yet .
But this thing at 1000 or so Rpm really rattles ...Really flaps
I do have XJ carbs on an xs1100 special ...
The hose is attached to #2 carb also ...
How much noise is normal ?? And I notice it has a little looseness to the advance unit not running.. Looks like rubber bands ..
I'll look closer..

[underdog57]

Duh

I looked closer and It turns out I had a missing cap on the carb boot , so guess where the vacuum hose went ?
Guess the excitment of bring old iron back to life got the better of Me...
I put the cap on the boot and the vacuum line to # 2 carb .
The advance seems fine now ...
A carb leaks , bet its the one with the aftermarket float.It is close but a little differant ...
Wow , it sounds good ..
To tweak it in tune now!!! After the float setting

[goldcoastguy001]

I had the same prob at one stage. Take the hose off the carb and suck n hold the vaccum with your tounge or pinch the tube whilst you keep sucking on it. if the advance mech keeps moving back after you pinch the tube closed (ie hold the vaccum) the diaphragm is most probably to blame....not sure bout over there but here in Aussie there is a company that reco them for around $35......and it makes it like new.

Cheers

[underdog57]

Good tip .
I have the need to have a vacum pot redone...