Vacuum advance and oil leak

[SanDiegoMike]

Hello all-

I noticed something when I replaced my cam chain tensioner assembly recently. I still had the timing cover off when I started the bike, and I noticed that there wasn't a lot of movement of the vacuum advance mechanism when I revved the engine. I tried moving the plate by hand after I shut it down, and it seems to be sticking a bit. Any suggestions on how to free it up?
Also, I have this annoying leak from the right side of the top end. I think the half-moon cam cap is part of the problem, but it also appears to be coming from somewhere in the front around #4, and I'll be damned if I can figure out the source. Any ideas on this one as well? I'm tired of the top right corner of my engine being black, and oil being blown all over the front of the engine as well.

[79XS11F]

If the non 1/2 noon leak is between the valve cover and the head you might want to check your valve cover bolt torques. If they are correct and the leak continues it is likely time for a new valve cover gasket.
Rob

[skids]

Re: Vacuum advance and oil leak

Step one is to degrease/clean the bike. If you can make it leak while running the bike in the garage with a box fan cooling it, it will be easier to spot the source. If you have a crankcase breather filter, make sure it is free flowing to prevent "forced leakage." There is some sort of stupid manifolding gizmo in the airbox that directs fumes(?) from the crankcase into the carburators. Like a criminal, I removed it from mine.

[skids]

PS, I subsequently just installed a breather filter and plugged off the nipple on the airbox for the other two bikes.

[Yankman]

I had the same problem on my 79 F. Replaced the half moons and the valve cover gasket . No more leaks!!!. The half moons are still available I believe with MOTOGRID . Com You can look up original parts with them. Just make shure you order all the parts you need or want, at the same time, they are a bit pricy on shipping.

[TADracer]

I had the same type of annoying leak and it was the half-moons. The one for the exhaust cam to be exact. Must be some sort of strange airflow in the head fins there because it looked like it was coming from the head gasket near the #4 exhaust.

I ordered them from Parts-N-more, I think. If you are going to change one you may as well change them both. And dont forget a new valve cover gasket.

[SanDiegoMike]

Thanks for all of the responses concerning the leak! I will be replacing those half moons and the gasket soon. Anyone have any ideas about the vacuum advance plate?

[randy]

sandiegomike;

You can lube that baseplate, it's got a sort of bearing built into it that you can shoot some solvent into and work it in. Don't recall if you can reach it from the front, probably have to remove it. Also make sure there's nothing binding it like pickup wires, etc.

[pggg]

From Skids: " There is some sort of stupid manifolding gizmo in the airbox that directs fumes(?) from the crankcase into the carburators. Like a criminal, I removed it from mine.

Makes me a criminal as well, as I ripped that gadget out too Emission gadgets, burning off the hot crankcase air by sucking it thru the carbs and robbing performance. But if you want to save the planet, stop global warming, tsunamis etc.. then keep it in

[dewibp]

Don't forget to check the copper washers/banjo bolt for the tubing (lube line) to the head too. It is located on the back side of the head and can leak through to the front........