Yet more jetting questions, yes I searched...

[unlimitedjeep]

Well after looking back more than 10 pages and having no luck getting the search to accept any search terms I try I am resorting to a new post. Heres the deal

Upstate New York
2000 400EX
FMF PowerCore IV
K&N Filter

Very low hours. original tires but I have been fighting with fouling plugs constantly, snaps and pops out of the pipe and reeks of gas. I have already tried changing the pilot and main, I forget exactly what is in there now (marriage, kid, house buying put the whole playing around with quad on hold for a while but am trying to get back into), never played around with the mixture screw or touched the setting on the needle. What are you guys/gals with similar setups running. The damn thing also will never start when it is cold out, say below 55 - 50..Ideas? Thanks in advance!

[Pappy]

if the lid is still on, i wouldnt run much over a 155 if that. a 152 is what i ran with a slip on and filter with closed airbox.

the air screw is usually 2 1/4 to 2 1/2 turns out off the seat.

bad gas maybe? or is it a contant and ongoing issue.

[unlimitedjeep]

Pappy, thanks for the quick response. Yes it has been an ongoing issue. Usually I will mess around and try starting it with no luck or it will fire and spit and sputter and even if you feather the gas it still will not stay running. The plug will foul and I will give up or if I am not too frustrated I will throw in a new plug and it will fire and stay running, perhaps by that time the motor is somewhat warm and will now stay running. I know it is cold blooded but the jetting has still got to be off. I am pulling the carb this week to check again and see what I have in there. Should I mess with the mixture screw or the clip on the needle? Thanks again!

[Pappy]

id make sure the spark plug boot is in good shape and not corroded, and also check to make sure it is fully seated in the coil.

the 400ex is a bear to start at times, but if i remeber correctly we put 40 pilots in and then jetted accordingly. maybe remove the carb (PITA job) and clean it and check for obstructions in the main jet. i chased a small piece of debris for a month before finally getting rid of it :(


im sure others will chime in and offer suggestions, some folks on here really know thier stuff!