Engine Bogging Down and Loosing Spark??

[dr1979-340]

I recently went for a 20 mile ride with a restored 1979 440 Drifter.  Background:  I had the engine completely apart and replaced all the gaskets and seals.  The rings appeared good so they were not changed.  I did not mic them out. 

The engine would bog down and loose speed, like it was running on one cylinder instead of two.  It would then correct itself and run on two again and really take off fast.

Any ideas on why the engine would loose spark and regain it again??   If that is indeed the problem.

[rminier]

 A few simple, easy things to check...perhaps you already have.
    New plugs of the proper heat range?
    Check the gap of the plugs to be as recommended ?
    Have you recently untwisted (counter clockwise) the spark plug caps from the wire? Trim off a quarter inch of the spark plug cables, then tighten the caps several turns (clockwise) until they're nice and snug, and they are biting into new, fresh wire.
   All these are worth a quick second look.

If none of those help...then?
   Probably not carb related, since it's a single carb...if the jetting was way different from stock, you could have the symptoms you describe.
       So...stock jetting? Airbox in place? Fuel pump and impulse line all good?
   Probably not piston ring related, since it runs O.K. part of the time.
   Now, we would have to start suspecting points/condenser (did the 79 Drifter have them, or CDI...can't remember).
   Or, the external ignition coil can start to break down after it warms up.
   If it does have CDI, they can begin to fail intermittently. Probably the last thing I would try...the Kawi CDI's have been pretty reliable.
   

[Interceptor398]

Check the plunger primer for gas going thru the line to the carbs while the engine is running.  It can cause those symptoms.

[Boomologist]

Carb flooding? Plug fouling on one side?

[dr1979-340]

Hood wire was shorting out one cylinder.  I put fuel line over the wire and all is good.