Issues with 400ex not starting

[billyboy]

I got a 2001 400ex in pretty nice shape. The down size is it needs a new set of rings but still runs really well. Puffs smoke at start-up.
I know the jetting is off on it (changed from a R4 to a stock exhuast), but I am not sure how far off it is. It will not start and it is getting both spark and fuel????

If you try and start from the switch it rolls and rolls but will not fire.

If you pull start it, it fires right up? Any ideas?

[pitkendall]

well first off make sure your battery is charged up and see if you have an aftermarket cdi box if so that is your problem becouse most of them will not start with a aftermarket box in the winter. also change your jetting back to stock except for the pilot jet change it if its not already to a 42 pilot jet and that should solve your problem

[rob_990]

yea your jetting probably way off.are you running open air box? if not go to stock.but why would you want to downgrade your exhaust anyway?

[hondaman146]

i have to put my battery on a booster to get it to start even though it cranks fast, and then once the motor is warm it will start fine

[billyboy]

Originally posted by hondaman146
i have to put my battery on a booster to get it to start even though it cranks fast, and then once the motor is warm it will start fine

exactly! Mine does that now!


Did not really down grade. When I purchased this atv the exhuast was crushed. The stock was just what I had laying in the garage from a previous bike.