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whipit
08-06-2001, 08:35 PM
I have got a 2001 400ex that i bought for snow and mud use.I have not used it much since March because i ride my motocross bikes when its nice out...I am pretty sure that it stalls and takes so long to warm up because the pilot circuit is lean in stock form. Has anybody come up with a good jetting setup for a box stock EX?? i am at about 500 ft elevation. this thing has got to be lean. anybody reccomend a pilot and or main jet size??

NVR2L8
08-06-2001, 09:22 PM
A common fix for cold starting problems on a stock 400EX is to bump up the pilot jet and readjust the fuel screw. When mine was stock I bumped up the pilot to a 42, and that more or less solved the cold problem. I still had to let it warm up a bit before riding, but it eliminated the bucking and coughing. You can also go a little larger on the main as well...I'd say about two sizes. Just do one circuit at a time until you get it dialed in. BTW, I'm at the same elevation as you and ran a 42 pilot and 152 main for quite a while.

whipit
08-06-2001, 10:02 PM
thanx NVR ill give it a shot. this thing will flame out even after it has been warming up for 5 min. if you let it. very very lean. it even says something in the owners manual about honda having used lean carb jetting to help reduce emissions