#4 spark plug fouled. Temperaturw differences between plugs

[dwkfym]

Went in before this winter. There is no starting issue (starts up barely after first crank has time to finish)

[Dave Neptune]

If an a-4 starts instantly it is way to rich. Be sure the choke is opening. You could also easily have an air jet plugged in the idle circuit or main sequence. Also check to be sure the flame arrester is clear.

A good running A-4 BY DESIGN with an updraft carburetor should take a few turns just to get fuel UP to the manifold then into the cylinders. Quick starts and fouled plugs indicate a very rich condition. Have you tried to adjust the idle air screw?

Dave Neptune

[edwardc]

..... (starts up barely after first crank has time to finish)

This little factoid tells me that mix is almost certainly too rich.
Because the A4 uses an updraft carb, a properly adjusted mix should be a little hard to start when cold, even with full choke.

Some time back, I followed Hanley's example and installed an Air:Fuel ratio gauge on my A4. That, and an adjustable main jet, lets me get it spot-on at the proper 14.7:1 ratio. And it normally takes about 3 trys to start with full choke when cold.

A too-rich mix will run cooler, and produce more plug fouling.

EDIT: Once again, Dave types way faster than I do!