'33 VL not running on front cylinder

[panhead_jim]

I've been wrestling with getting my '33 VL running and just can't seem to figure out why the front cylinder is not running. The bike will start and the rear cylinder heats up "normally", but the front never get more than 15 degrees above ambient temperature. I'm only running the bike for a minute or two, but in that time the rear cylinder easily reaches close to 200 degrees at the exhaust valve. I've verified the following:

Both spark plugs (D16s) produce a nice blue spark and are gapped to .030"

I've switched the spark plug wires at the coil which made no difference

Timing is set correctly (verified I am timed to the front cylinder by opening the front intake valve cover to watch when the valve closed as I rotated the engine) and the points are opening on the narrow end of the points cam

Point gap is set to .022"

Valves are adjusted correctly (.005" on intake and .007" on exhaust)

I checked the intake manifold for air leaks by mounting a plate on the front of the carb with a valve stem and pressuring the system

Valves were checked on the bench using a fluid leak down test to verify they were seating correctly (yes, I've had the cylinders off once already)

One thing to note is that while the bike is running, it is blowing out white vapor from the carb in time to the engine pulses.

My next step is to pull the cam cover and make sure the cams are timed correctly, but wanted to make sure I've exhausted all other checks before tearing back into the motor.

Any thoughts, guesses or speculation welcome!

[Steve Slocombe]

Dear Jim, that sounds pretty thorough so maybe we're down to the cam timing. The 1930/1 magneto models have two timing marks on the number four cam and, if you happen to have used one of these on your restoration, you can time the front exhaust valve incorrectly. Please let us know what fixes it for you.

[Jim]

When I first read the topic my first thought was a plug wire inside the coil, but you've already eliminated the "Spark" question. Sounds like a timing problem. I can email you a pic of what the timing marks (1936 VLH) look like in "real life" rather than the drawing found in the owners manual. PM me if you are interested.

[T. Cotten]

Panhead Jim!

It sounds like a classic vacuum leak, so I must ask about your manifold testing.
When you say "valve stem", there isn't a valve in it, is there? The point of pressurizing the manifold is not to hold air, as it will always leak past valves, guides, testplates, etc. It is to make bubbles show you where the problem is.. http://virtualindian.org/11techleaktest.html

Do you have a constant, regulated air supply? Hand pumps, air mattress pumps, and reversed shop vacs have led many, many folks astray when testing, with false negatives that made for aggravating tail-chases.

.....Cotten