[Country Boy]

I know that 400ex have been known for very VERY cold engines, and i took that into consideration when i got it. but this is getting way outa hand. :icon_cussing:I havent rode my 400 in 2 weeks, and i tried to start it. it took 2 hours to electric start it and to roll start it behind the rancher. the engine still didnt keep firing. it turned over and ran for like 3 seconds and died. could this be my spark plug???? Does my 400 have a fuel primer like my utility 4wheelers???

 

[Billy250X]

Sounds like your not getting fuel.I don't think they have primers but make sure it's on choke and pump the throttle a couple times.

 

[Helmut]

Probably would be best to just go ahead and buy a new spark plug, anyway, as they don't cost that much. Is it getting fuel to the cylinder? If it is, then, it sounds like you might have a stator, pick up coil, ignition coil, or CDI issue. After cranking it over for a minute, take the spark plug out and look at the end of it and see if it is wet with fuel on the end of the plug. If it's wet, you are getting fuel. If you think it is firing, but not getting any fuel, pour about a teaspoon of fuel into the spark plug hole. Screw the plug back in, quickly before it evaporates and put the plug wire back on and try to start it. If it is firing, it should start for a second or two, until it burns the fuel out that you put in. That is, if it is in time and has compression and is firing, it should start. If it don't start, you need to check the firing. The easiest way to check it, if you don't have one of those firing testers, is to pull the plug wire off the end of the plug. Take a phillips screwdriver and stick it in the end of the spark plug wire boot, making sure it tips the metal piece inside. Lay the metal piece of the screwdriver close to the head somewhere. About 1/8 to 1/4 inch away from the head should do. Make sure the kill switch is in the run position. Crank the engine over. Fire should jump from the metal part of the screwdriver to the head if it's firing. Remember, if you are tipping the metal part of the screwdriver or the wire, you will probably get shocked if it is firing. Actually, it would be easier to test the firing first. Then if it don't fire you can pour gas into the spark plug hole and try it. The spark should be bright blue. If it is orange looking or you don't have a spark at all, then, you have a firing problem. If this is the case, then, you will need to check the resistance across the stator, pick up coil, and ignition coil with an ohmmeter. I don't know what they should read off hand. You will probably need to get a repair manual. If it's not one of these, it might be the CDI. I don't know of anyway of checking the CDI, except to replace it with a known working CDI.

 

[Redracer]

Try going up one size on the pilot.

 

[tomgodd]

Agree^^^^^^^^^^^^. My 400 is cold blooded! Change the plug. You may need to change your jetting for the cold weather. I change mine when it gets cold. It runs alot better.

 

[300ex power by monster]

i just adjust my air screw till it run righ with the weather

 

[Helmut]

When it starts and runs for 3 seconds, will it start back and run or does it not want to run at all? When I wrote the post above I was assuming that it wouldn't run at all longer than 3 seconds. If I misunderstood you, then, disregard my post above.