jumped timing chain

Have you pulled the spark plugs to see if they look like they're running too hot (really white)? Since you feel that the engine is running hot, it's possible that the wrong heat range plugs are installed. This wouldn't necessarily explain the apparent blow-by, but it's worth checking to confirn your suspicion about running hot. Ed

The lean running thing with the fuel cap breather seams to be the most promising. However, I'm gonna have to replace coil first just to get it running right again.
Tune up involved changing plugs, points and condenser, setting gap, and adjusting timing. Carbs were also tweeked. The bike ran so sweet, then crapped out. I began noticing the heat rolling off the bike just before all hell broke loose. Gonna try to install electronic ignition and eliminate the original style coils. Any suggetions are welcome.

Didn't notice any specific mention of lubing the ignition advancer unit (it lies right behind the points plate where the points & condensor are)

If this thing is sticking the bike will run very hot.

Like, pipes will glow red at night hot.

You'd think that an engine getting this hot would ruin it, and if you were talking about a new bike you'd be right. My friend has a KZ550 that was ran with a stuck advancer for several years before I got to it and it runs fine (less a little head gasket leaking) still.

I digress. You may be noticing a normal amount of heat from the engine - is anything glowing or smoking? Those are too sure signs that the engine is getting too hot.

What kinda miles you have on that beast?

BINJIEU wrote:

Carbs were also tweeked. .............

Gonna try to install electronic ignition and eliminate the original style coils. Any suggetions are welcome.

What did you tweek on the carbs?

Until you get the overheating fixed I don't see how installing electronic ignition will change anything, and sometimes this mod brings its own problems during setup. I say fix one thing at a time.

Duck wrote:

Does oil smell like gas?
Does oil level change magically all by itself?
Do you have a vacuum petcock? If so, are there cracks in the activation hose?
Is your timing advance sticking?...

Am also suspicious about possibility of (1) fuel intrusion into crankcase, and (2) advancer stuck closed. Might explain decent temporary performance after tune-up with new plugs and oil change. Fuel contaminated oil may not be readily apparent by viewing through the inspection glass. Strobe type timing light is best to actually see operation of advancer unit.

I would use a heat probe for a dvom to determine what the engine is really running at. Or use a thermometer for a turkey frier:P and stick it in the oil fill hole to see if it really over heating.

The sucking sound may be normal. My bike makes an intake noise so loud it hurts my ears.

How is your petcock configured? Do you have two tubes (a vacuum and a fuel line) going to your carb. Make sure these are in good shape I.E. replace them.

Further, do your carburetor rubbers (the things that mate the carburetor to the engine) have rubber plugs over the metal nipples? This will cause unusually loud intake noise and overheating, but probably not to the degree your experiencing.

How do I check the advance mechanism? I inspected it prior to the tune up, (removed timing plate assembly
to see that springs weren't busted), but didn't move anything. Can this be checked without undoing anything timing-wise?

The pro tweeked the carbs "idle" mixture, I believe.

BINJIEU wrote:

How do I check the advance mechanism? I inspected it prior to the tune up, (removed timing plate assembly
to see that springs weren't busted), but didn't move anything. Can this be checked without undoing anything timing-wise?

Grab the end of the advancer shaft, the one that opens the points, and try to twist it clockwise. It should move and the springs will snap it back when you let go.. if you can't get it to turn then it's stuck...

If I twist the shaft, wont the crank just turn clockwise?

Mmmm, now I'm not sure. I know I can twist mine when it is off the bike, I think if you just twist the part of the advancer that opens and closes the points it shouldn't move the engine. And I would think if you do this and the crank does turn, then the advancer is stuck.
Just try it, or take off the points plate and remove the advancer. You'll know soon enough if it's rusted tight. Some are a real mess.