Topic: # 3 not firing, but plug doesn't foul ???

[2tall]

Hey guys, I rode into work this morning, and about a mile into the 10mi trip, I noticed a bit of a miss. Didn't matter what rpm, it just missed. After I spent my lunch break of chasing plugs, wires, coils, condensers... I have confirmed that it is cylinder #3. All associated components are functional.

(Bike is a 76 550 with 13k miles)

Timing and gaps are spot on and it ran like awesome last night, so nothing "sneaking up" on me either.

I rode it home (begrudgingly) on 3.5 cylinders and expected to find a fouled plug. Nope! It was clean! Is the #3 carb plugged? This is the only thing that makes any sense to me. But I'm tired, out of time for tonight, and generally pissed that I have to take the minivan to work tomorrow when its supposed to be 70 out... 

[Don R]

If the plug isn't wet and not firing I'd have to say no fuel or very little.

[kghost]

If theres a time lapse between shutdown and pulling the plug it may not be wet.

Remember...the engine SHOULDN'T foul plugs to begin with.

If the plug is not firing theres no reason for it to be black and all crudded up.

Some engines with issues will foul the plugs resulting in black plugs.

Test the plug.

Shouldn't be the coils as they fire 2 plugs.

Could be the lead, the plug, or the cap on the lead.

Could also be carb related.

You need Fuel (in the right ratio), Air, and spark (at the right time....since one of the two plugs on the as coil is firing its prolly at the right time)

[1timduke]

Hmmm... try a brand new plug, see if it changes anything.   Or switch the #3 and #4 plug, will you then have a dead #4, a dead #3 or a dead #3 and #4???   

If it's missing throughout the range, it could be a air leak on the #3 boot, I'm assuming you switched the #3 and #2 leads?   

Try spraying WD40 around the boots, see if the idle changes.

-Tim