i have a customers bike in the shop that is fouling plugs left and right. the bike is a stock 94 with a pipe and jet kit. the bike had a 40 low speed with a 124 main and the needle was in the middle clip with a washer under it. it would fould the plugs within 3 or 4 miles. cleaned plugs, left low speed alone since it is stock, replaced 124 mains with 112.5 which is 1 size smaller than stock, and removed the washer from under the clip. the bike runs great while you're riding it, but if you let it sit for a while and start it back, it will fould the plugs. the fuel pump is bad on the bike, and they have it gravity fed, which seems to work ok. the honda dealer swears its the float height letting gas leak down overnight and flooding it, but i turn the petcock off when i let it sit. have any of you had this problem before, and do any of you know the factory float height so i can check/reset these. i'm at my wits end with this P.O.S.

 

do you just turn the petcock off, or do you turn it off and the let the engine run for a bit?

If not, I would suggest doing this and see if it helps. If it doesnt, then that means your petcock is not working like it should and will need to be rebuilt. they do fail quite often.

the mechanic could be right, its either that, or the needle isnt seating properly to the seat and allowing gas into the carbs even though the the floats may be at the right height. the other possibility is the floats do not float any more. they can develop holes or coorode, or even just become saturated after time and loose their buoyancy.

I would do a complete rebuild on the carbs. its old enough that it probably needs it. especially if its spent most of its life unproperly stored. I would especially think this since it only runs decent with a size smaller than stock jet.