Not getting fire on 3rd cyl

I’ve recently got my carbs back after being professionally cleaned and I’m noticing my 3rd cylinder still doesn’t seems to fire. I’ve confirmed spark and compression as well. The bike will fire up and run no problem, but when the pipes get to temp, I spray them with a spray bottle with just water in it. Cylinders 1 2 and 4 the water can’t even touch it without evaporating instantly. But water will stay on the 3rd pipe. Any suggestions?

(1986 Maxim x700x)

 

Have valve clearances been checked and adjusted? Compression in all cylinders? A cylinder can weakly fire (and thus not get hot) due to low compression, lack of or weak spark. or lack of fuel. Lack of fuel is the easiest to check for:

Try bumping the choke on for a few minutes and see if that cylinder warms up (the choke has its own separate fuel supply circuit, different than the fuel jets). If the cylinder warms up, that points towards a "lack of fuel to #3) for some reason. If it doesn't warm up.....and assuming the choke circuit is actually function on that carb .....then you can eliminate the lack-of-fuel issue from the checklist.

 

Just throwing this out there, are you working with a fresh set of plugs and I mean fresh from the box? Reason I ask is I've had plugs show a nice strong spark from the wire to the terminal but nothing on the end because the energy was being channeled thru the carbon instead of the electrode gap. Just a thought.

 

I would guess that carb 3 needs more cleaning or the float needs to be adjusted. If you have spark from the plug, and it runs on spray, then you must be missing fuel to that cylinder. Not sure if you have the air box boots off the back of the carbs? If you do, you can start the bike, put the palm of one of your hands over the intake of carb 3 and see if that fixes the issue. If 3 does start to run with your hand partially over the carb intake, then it is either dirty or the fuel in the bowl is too low.

Just be ready to remove your hand from the carb back. Start by covering a little bit of it and work to closing off the opening. This will force the carb to pull more fuel from the bowl. It will also try to suck you hand into the carb, feels weird until you get used to it.