Why do I keep fouling plugs?!

[arena314]

I have an 03 Banshee with stock internals and bolt ons. I have dmc headers with fmf powercore silencers open air box with uni filter vforce 4 reeds bost bottle and that's it for motor mods. I have 290 mains and 30 pilots in the carbs with the needle in the 3rd position. The bike runs pretty good the only issue is it bogs alot starting out in 1st but is good otherwise. What really bothers me is that the bike fouls plugs all the time. Every few hours of riding I have to put new plugs in. The plugs looks rich when I pull them out so what's going on? Should I put the clip on a different position or swith the mains? Or could it be the pilot. Thanks for any replies

[Sandking]

When you start is it a lean bog, or a fat bog. If you idle too long with a fat pilot it could foul the plugs. You could start by turning the air screws counterclockwise 1/2 to full turn and see if it helps. Your jetting sounds close although you left out temp/altitude.

[RadarRacing]

Want a simple answer? Lean out your needles 2 or 3 clips. Raise clip/lower needle. Turn out air screws to 2 or 2.5 turns if they are in less than 2 turns. If it has over 25 pilots go down to 25.

I would think 290 mains should still be good and not he too rich.

 

If you want an explaination as to why, then it is because the low speed air/fuel mixture (AFR) is too rich. This can also be cause by a somewhat wornout motor, weak ignition, old crappy gas, too rich on the pilot, needle, or mainjet, clogged air filter. If you pretty much dont have to worry about all those problems then it is just a tuning issue and can be fixed with needle , airscrew or pilot adjustments.

[arena314]

So if I want to lean it out to I move the clip up or down?

[Sandking]

Up

[trickedcarbine]

A 30 pilot is quite fat for a few bolt ons and a stock air box. Especially with that UNI foam filter. Those need constant washing if they are gonna keep breathing well. Try a 27.5 IMO since you have a few mods.

[arena314]

Ok I'll go down to a 27.5. What about the needle?

[Craig B]

Ok I'll go down to a 27.5. What about the needle?

Make 1 change at a time. 

[guns4children]

Make sure you have 2 new plugs in before you test it after changes.

[RadarRacing]

So if I want to lean it out to I move the clip up or down?

To lean out off idle to mid throttle position on the needle you need to (raise the clip which lowers the needle)

[sleeper06]

Head gasket small leak

[arena314]

Ok so should I just go down a size in my pilots or should I try adjusting the needle first?

[Larry's Shee]

Won't cost anything to adjust clip or air screw first. Best to only change one thing at a time in small amounts, especially if inexperienced at tuning.

Could also be how you ride. Try opening it up more often in the lower gears, not "lugging" it like a 4choke.

 

Been playing with smokers since early 70's, have replaced a zillion plugs. Just nature of the beast, IMO.

[arena314]

I moved the clip up 1 position and put the screws out 1.5 turns still has a bog out of idle and doesn't want to idle perfectly it almost has a sputter at idle but the carbs are synced. I think the pilots are to big

[arena314]

My problem ended up being horribly low compression lol. Started the tear down I'm going to do a port and polished 380 probably for now