69 Commando Right Exhaust Very Hot

Hi,

Continuing trying to get Commando back on road after a dozen years sitting. New Pazon, rebuilt carbs, new steel tank, was rebuilt by Chris G in DC just before stopped riding because of ethanol/fiberglass tank concern. Was running a little rough, called mechanic who said not to ride it until I'd coated or replaced the tank. Took 12 years to get back to it.

Got it going, timed, but have run only a little. 100 pounds compression each cylinder. Was worried about possibly overheating engine, got a laser temp gun.

After just a minute of running, reasonably good idle, the right exhaust goes up over 400F (assuming my $18 temp gun is accurate, seems to be), left under 200F. Left cylinder around 100F, right about 120F. Was extremely careful in going over the carbs and remounting them that there are no air leaks.

Any suggestions?

Tim

100 psi seems low. If not run since the rebuild have the rings seated?

Quite possible rings not seated, should see the guy who did it at the Norton meeting tomorrow. I didn't drive much then, took kids occasionally to elementary school on it. Also compression being measured with me kicking, enough to start it but perhaps not like a mule. Also don't think I had the throttle open, will recheck.

Need to check compression with throttle wide open. Five or six really good kicks or until the guage quits climbing. Also needs to be a hot engine. Cold engine could be 20 psi or so lower.

Exhaust valve not seating or head gasket leaking.

hot cylinder has retarded timing, I had a pipe glow red once!

Haveing Pazon ignition would mean timing has to be the same, both sides. Although an actual 100 PSI is low, being equal would mean the valves and rings are in the same state too. What is a "reasonably good idle" ? Could be the hot cylinder is doing most of the work while the cold one is just loafing. Balance and idle mix issue?

I'd check my compression gauge against another one if re-checking with throttle wide open still produces only 100.

Danno said:

Exhaust valve not seating or head gasket leaking.

Click to expand...

Exhaust valve seems plausible. Check your lash first.