Topic: #1 plug keeps fouling

[slambert49]

hey guys i have searched for answers on this site but cant seem to find one. my #1 plug keeps fouling. all of the other plugs are showing great color. my bike is a cb750k2 it has pod filters and a 4-2-1 exhaust. i tried taking off the pod on that cylinder and it didn't make a difference. i shot some carb cleaner down the carb, that didn't help, i also tried unscrewing the pilot like a half a turn then a full turn. and its still fouling. the bike has plenty of power still but i feel is i can fix this problem it will have even more power. it idles at 1100 rpm pretty smoothly except for a little pop here and its noting to serious because the exhaust had no baffle and is drilled. it smokes a little on start up with some grey smoke but goes away after like 15 seconds. i just adjusted the points if that helps. if there's any other info you need just ask but please help

sean

[Duke McDukiedook]

Run a compression test? Leak down test?
Check your spark, spark plug wires and connection of all?
Carbs synched?

[1timduke]

Run a compression test? Leak down test?
Check your spark, spark plug wires and connection of all?
Carbs synched?

+1

Is it fouled from soot, or oil?

-Tim

[Alan F.]

Have you had the carbs apart?  I remember someone posting a similar issue recently, the cause was eventually nailed down to the carb slide being installed backwards in only one carb, they apparently fit either way but only work correctly when they're in the correct way.

[slambert49]

its a dry black soot like substance on the plug most likely from a rich mixture although the valve seals/guides could be going on that cylinder. i haven't taking the carbs apart i  just got the bike 4 months ago. I was wondering if it could be from poor spark due to old wires from the coil. i have been having a problem with the caps staying attached to the wires (are they supposed to screw on?) and the inside of the wires looked kinda of black, cleaned them a little bit with some electrical cleaner also did the boots, then i got the boots on and taped with electrical tape so they wouldnt pop off anymore. do you think some new coils could be an answer since there wires cant be replaced? most likely would not want to take the carbs apart just yet since riding season is starting but i guess you got to do what you have to.
 

[1timduke]

You can snip off a little of the ignition lead and thread the caps back on, it'll give a little better connection.   

Tappets adjusted?   Make sure the engine is cold when you do it.   If the clearance isn't correct you could be getting exhaust gases building up in the cylinder fouling the plug, it may also be causing the backfire.   Easier than pulling carbs

I'd still run a compression test just to know how the rings/ valves are doing.

[slambert49]

will do a comp. check also refitting those boots thanks guys

[Spanner 1]

K2?, well 2, 3 and 4 fire ok with good color..longshot, but I had the same with a K5, exact same...turned-out #1 air-screw was missing its spring and was turning in with engine vibration ..turned-in = all gas, no air = fouled plug....OR blocked idle air 'tube', no air to mix with available idle gas...

[HondaMan]

It could also be the emulsifier tube's air supply: this is a hard-to-clean passage that runs from the tiny brass orifice in the carb's air horn, which makes a dogleg turn, then runs to the emulsifier tube (aka "Main jet holder") in the center of the carb. When these get even partially blocked, it causes fouled plugs, and is quite common after the bike has been sitting a while.

Search for "emulsifier" or "air horn" and one of the many posts will have my step-by-step on how to clean it.