#1 fouling plugs. Fuel?

[IanC]

I've been having problems with the #1 cylinder fouling the plug after less than a hundred miles. I was still running points and figured it was most likely an ignition issue so I installed a Dyna S and did the coil relay mod. Ran like a champ, better than ever. Tonight though I went to go for a ride and once again #1 is fouled. Was running great when I took it to work, parked it at home for 4 hours, go to take a ride and runs like crap. The plug smells like fuel and is pitch black. If it was #2 I'd know it was most likely the petcock but this baffles me. I tossed one of the old plugs in it (not the old #1 obviously) and she runs fine again. Now I did not replace the plugs when I did the ignition conversion but will do so tomorrow to see if it was maybe just mostly fouled before but I'm thinking I'll still have the same issue soon.

[tejasmud]

My guess would be possibly check the #1 plug wire and plug cap connections.

Other than that the #1 carb could be providing too much fuel.

Air screw not set right, float too high.

Hard to say. Assuming valves are in spec, and carbs are in sync.

If #4 is good, I would rule out the ignition and coil.

E

[IanC]

Wire and cap are brand new. That's why I went to the Dyna, the wires were looking sad. The valves are recently adjusted. Quite possible in the carbs. Sourcing everything for a full on rebuild soon.

[Big T]

Ian

It the float most likely, probably sinking

Test float in a can of gas

Also, on VM carbs, a bad petcock affects #3, not #2 (that's CV carbs)

[tejasmud]

I see. Hmmm...

Carbs been cleaned or no?

If the passages in the idle circuit are gunked up causing a restriction of air through the air screw passage it would draw more fuel.

When you get into the carbs I would inspect the #1 needle jet and needle. The thing to look for would be wear on the needle. If the needle has rubbed enough against the needle jet, the hole in the needle jet can become egg shaped. This will increase fuel through that circuit as well. The choke plunger not sealing can provide more fuel. Checking the float in #1 as it would be subject as well, but best would be to know the actual fuel level in each float bowl.

As BigT mentions check for boyancy of the floats.




E

[hampshirehog]

Choke plunger not seating properly (check mechanism alignment) or the rubber has cracked / gone rock hard.