Starting problem

[Shonto rider]

my 400ex wont start...It turns over and fires, but wont keep running.

[honda300EXtreme]

kind of a broad statment, but id check your plug and clean your carb, to start with

[vett_09]

Is yours stock? Have you rejetted yet? Because the 400s are temperamental when you start them cold. Before I started adding mods to mine, I had trouble starting too. I had to choke it, to get it to start, when it did start, I moved the carb lever to half choke and gave it a little throttle to keep the RPM's up. I would do that until it warmed up and I could feel a little heat coming from the engine fins. Once it was warm, I moved the carb lever all the way open. It was a pain, but when I rejetted it was much easier to start.

[js600]

i was having the same problem with mine. i ended up replacing the plug and cleaning the carb as stated above. i also replaced the fuel screw with an extended one so i could fine tune it without special tools. starts right up now first try. about 10 seconds with choke closed then slowly open it up.

[hondaracer57]

check ur wiring too it could be ur kill switch expecially if u got an aftermarket kill switch...