I haven't rode my KFX 400 in a while. Battery was dead. So I jump start it. When I get about half way through first it cuts out. Kinda like I'm not getting enuff fuel or maybe too much. It does the same thing in neutral when I hit the throttle. If I hold it, the bike cuts off. Any suggestions???????????????? Oh yeah, I have had this machine for about about 3 years and it has never been serviced other than an oil change. I'm gonna try to change the spark plug myself. Never done that before. Not even on a car. Help me out guys.

 

i had an 03 kfx 400 and my floats in the carb always got stuck. in every gear including neutral. it only happened to me after hitting whoops in 4th or 5th gear though. what i did was take off very slowy get into 4th or 5th and down shift into 2nd and from the down shift the bike would most of the time correct itself. other ways i fixed it if that doesnt work is bang the carb with something!!! it worked once or twice! also depending on how long it has been sitting your carb might just need a good cleaning. try that first. hope this helps man

 

spark plug is easy... have the guy at the parts store show you how to set the gap...
turn bike off (electical, shesh, not even an east texas dumba$$ would try it running)
pull plug wire
test fit spark plug socket to find correct one
turn old plug out...
look at it.. is it BLACK, black and oily, tan, red, or just "metal" colored (it matters)
hand turn in the new one
turn slightly tight/snug with socket
reattach wire, snap it all the way down
start bike

kick self in tush for not using stabil or some other such gas keeper

pour in a can of fuel cleaner (your choice)
run bike around for an hour or till empty/reserve
turn off, fill with premium gas and gas cleaner
go play, it will eventually get better

or pay someone to clean/rebuild your carb

 

If it has been sitting for a while, there is a chance your gas is bad. Empty the tank and put some fresh fuel in it. It sounds like your carb needs a good cleaning. The spark plug change is simple. Lefty loosey and righty tighty. Like stated before, use a socket wrench to get it out. When putting the new one in tighten it by hand and then just snug it with the socket.

 

Thanks guys. I tapped the side of the carb. Good to go.

 

If it happens again then you probably have some gunk in there making it stick.