Cold Weather = Won't Start

[ouhockeyplayer]

I have a 04 400ex with Dubach slip on and K&N filter. Right now, it has a 42 pilot and a 160 main in it and it couldn't run better in warmer weater (plug is the perfect cardboard box brown) However we are down into the teens and single digits in Michigan right now and it wont start worth a crap. The only way I can get it going is to give it a little gas while pushing the start button and staying on the gas untill it warms. After fiddling with it like this for 5-10 minutes it will finally will idle on its own. Is this normal 400ex behavior in this type of weather? if so, I guess I am sticking to the snowmobile for the rest of the winter.

[DP400]

after getting it warmed up mess with you idle screw could be to low, turn right to increase. also if it hasn't ran in awhile that could cause it. i always put 93 in mine cause i don't ride it everyday and if you let gas sit for a month or so it'll go bad. get it running and burn up some of that gas and mix in some fresh 93 should help.

[ouhockeyplayer]

Does burning a higher octane fuel in the winter really help with starting? I try and start it up every week or two so I don't think the fuel would be bad.

[DP400]

Not sure, I'm preaty sure it takes longer for it to spoil though. now that they put ethenol in the gas it doesn't take long for it to go bad. I also think that running 93 makes it run alittle better, maybe its just me.

[mittman]

my bike is like that. normally i start it up and use the throttle to keep it running and take it up and down the driveway in 1st gear 2-3times. then by that time it will idle on its own. since i have been working out in the garage a lot ive kept a fire going which it stays from 60-70 degrees in there and that makes the bike start easier. 93 definitely makes it run better. i guess if it makes it run better then its got to make it start and warm up quicker.

[rob_990]

ya i always pump the throttle twice and give it a little gas and it normally starts right up.then i drive really slow down the road so it cant die on me.then after like 10 mins its warmed up and idles/rides like normal.

[bigredisb]

Thats exactly how my 3 400exs are. My 07 is cold forever (10+ minutes) and my white 08 I changed the jetting and its pretty good. The newest addition I just picked up is a red 08 ex and its cold at idle mid and topend.
I think its the nature of the beast.

[sc400ex_rider]

the ex carb has an accelerator pump in the carb every time you push the throttle all the way it squirts a little gas in to the port. if you take the air filter boot off the carb you can see it. the ex it jetted way lean from the factory for emissions purposes it says so in the owners manual. i dont think the honda engineers ever realized us crazy americans would ride the quad in 15 degree weather. in that kind of weather you might need to go up to a 50 pilot and rejet for every winter/summer

[Wingnut]

If you have the stock rev box try plugging it back in. The stock ones allow the spark plug to fire at a lower rpm, like when starting a very cold engine.