I have a stock 75 with a 2.0 liter engine - converted to webers. I can only get the engine to run on #4 cylinder. Rebuild the engine top end, rebuilt carbs, timing looks correct at 27 degrees. What am I missing?

Not trying to be smart here but how do you know it is only firing the #4 cylinder? If it was running only one one cylinder it would seem difficult to set the timing correctly

I assume you checked for spark at each cylinder?

Valves are set correctly?

Verified fuel flow through both carbs?

Plug wires in correct order?

I've never seen a 914 engine running on only one cylinder.
Two maybe - but one?

1432

They don't run on one. Something strange is afoot at the circle K.

Test #1 - remove spark plug wires and engine rpm should change. I remove #1, #2, #3 without affecting RPM - remove #4 with all the others connected - engine stops.

Test #2 - spray carb cleaner over the intake port of the carb - again the engine RPM should change - Only #4 is affected.

Firing order correct 1432

Still balancing both carbs. Heads replaced and valves are set correctly cold.

Still thinking its something stupid. It will go 55 miles and hour will one cylinder until you hit a hill of course.

Balance is off.

If you pull all three (1,2,3) at once does it continue to run?

If you are pulling them one at a time all that proves is the cylinder is not pulling its share of the load.
It could still be burning enough fuel to not be a significant burden on the idle.

As Rich said, the balance is off.

I followed this:

http://www.redlineweber.com/html/Tech/idf_...nt_controls.htm

Linkages should be disconnected, air bypass screws closed, idle mixture screws out 1 turn, idle adjust in 1/2 turn in after touching arm (both the same).

you should read the same flow on all 4 barrels.

Stu