I'm having an issue where plug 3 keeps carbon fouling, eventually to the point it wont fire. I take it out replace it and it's back to normal for a while until it starts to foul bad again to where it wont spark.

What's the best solution? Drop needle height or more simply adjust the pilot screw? The sync is good it idles very well and steady, good throttle response, it was rejected but every other plug wears normally and doesn't foul up

I dont want to just reject the #3 carb but I need to solve this problem depending on how often I ride (I'm in fl almost ride daily) it fouls up every month or 2

I just wanted to get a second opinion before I adjust the pilot screw I'm thinking I should try that before adjusting the needle?

Just for reference compression is fine, no signs of piston ring wear, recent oil change and the level seems fine, timing is good, battery is newish spark wire is good within spec and so is the coil so I dont believe it to be an electrical issue, and theres no oil fouling so it's nothing to do with rings or oil leak seems like a straight forward too much fuel that isn't completely igniting leading to carbon build up. I've cleaned the carbs relatively recently and tested the floats so I'm positive that the float is fine and I replaced the float needles and clean its seat so I'm pretty confident that it's not a float issue but I guess I cant be positive until I take it out and check again

Thanks for the help

 

Here's my thoughts:

1. My first guess would be the float needle/seat is leaking. This is letting too much fuel into the bowl and flooding #3. But you say you've checked this and replaced the needle, so moving on.
2. Check the idle mixture screw. I'm skeptical of this since it affects only idle. But its so easy, just do it. They should all be set the same. The pilot needles have very small orings, pull the needle and check the oring too. remember these are now 20 yo bikes, with lots of small rubber pieces that can dry/crack/tear or let air in.
3. You've got dirt down one of the air bleeds and it's acting as a choke on that carb. You'll have to pull the carbs and clean #3. Take a lamp cord, split the wire into a very thin wire, use it to make sure the air bleed are clean and blow it out with compressed air. Do it from both ends, top of air bleed and the jet/bowl end.

 

Cool thanks for the response I have all the pilot screws set at 2 1/4 and last time I rebuilt the carbs I checked the orings and tips, I had one tip that was completely gone and I replaced it so I feel confident in the orings but again no harm in checking it's easy enough.

I'll definitely check the air bleeds it's completely possible something got in when changing plugs or working on the carbs with the air box off I have a k&n filter so I doubt anything got through it but I can see something getting in there when it's off and not noticing it. I made sure to clean them really well and used compressed air last time I cleaned the carbs but I can do that again and since I'll have the carbs off and bowls off I might as well recheck the float needle I might even have a extra laying around and maybe I'll replace it just to be sure