so i was ridin down a creek today and the 400 started missin. i stopped reved it up and it died. i figured the electronics must have gotten wet. after lettin it sit for a few minutes it still wouldnt start. so i started messin with a few diff things. it would start and run with the choke on as soon as i would turn it off the damn thing would sputter out. after about 10 mins of ridin with the choke on it ran fine with out it. 20 mins later it did the same thing. after ridin for a few with the choke on i turned it off and it ran fine for the rest of the day. any ideas what it may be??? and no water got in the airbox. [img]i/expressions/face-icon-small-confused.gif[/img]

 

If water didn't get in your airbox, then you have a leak between it and the carb because water DID enter your carburetor or the choke being turned on wouldn't affect it by making it run better.

You can't burn water in the combustion chamber....only minor condensation.

Water will remain in your system until you drain the float bowl a couple of times. No big deal at all.

 

here's a thought- dirt in carburetor. The choke is a separtate fuel circuit. your main jet probably plugged with a piece of dirt, and your fuel supply was cut off, so it died. you turned the choke on, so then you have an alternate fuel supply, so it runs a gain. the piece of dirt was no longer being pulled up the main jet when you're running it on choke, so it fell out back into the float bowl, and when you turned the choke off, you had fuel in your main jet until it picked up the piece of dirt and plugged up again. the same thing happened to my buddies rancher when he rolled it over totally underwater in a mud puddle.

 

The 400ex has a butterfly choke, so it isn't a separate fuel circuit. I'd bet water is to blame. Not a big deal to fix at all.

 

thx for the help. ill let you know what i find.