Too hard to start.

[JP400ex]

I just got a 400ex off a buddy and he had a ton of aftermarket stuff put into it. I am mostly a trail rider and just switched from a 20 year old atc 200x. Anyways, the EX has a high compression piston in it (i think something like 10:1) and it basically will NOT start in the cold. Granted it has been down to like 5 degrees here lately and the bike is in my unheated garage but you would think a 2 yr old atv would start fairly easy, even in cold conditions. My 200x started on the 2nd kick last night. In order to start the EX i have to put my salamander heater on the engine and then it will usually start after about 10 minutes of the heater. Is this just because of the highcomp piston? Is there any tricks to getting it to start easier. Im afraid if i take it riding at the forest the cold ride there won't help!

Heres a pic of my new ride.
http://parsons.dynu.com/400ex/400ex.jpg

[Pappy]

find out what pilot jet is in it

[NeonImpact]

Did he happen to remove the choke, change the jet, or any settings?

search the site for info on the choke and jet info and see what you can come up from there..

if not post in here again, and we'll see what we can do for you bro..

NICE RIDE BTW! :eek2:

[NeonImpact]

Read up on this some bro...

http://www.exriders.com/vbb/showthread.php?s=&threadid=86574

[mustang]

the EX is different from your atc the carb has an accelerator pump like an older car has. first thing to try is just pump the throttle 10 times and try to start it if that doesn't work try this change the 38 pilot jet to a 42' and give the thottle 10 pumps it should start right up remember that you may have to fether the throttle a bit till warmed up. The EX is very cold blodded and worse if modded... Hope I helped this worked for me and I live in Connecticut

[Aceman]

Originally posted by mustang
first thing to try is just pump the throttle 10 times and try to start it if that doesn't work try this change the 38 pilot jet to a 42' and give the thottle 10 pumps it should start right up remember that you may have to fether the throttle a bit till warmed up.

If you have to pump the throttle ten times you need a bigger pilot.
You shouldn't have to pump it more than 3-4 times. Ever tried the choke?

[zephead400ex]

Originally posted by mustang
the EX is different from your atc the carb has an accelerator pump like an older car has. first thing to try is just pump the throttle 10 times and try to start it if that doesn't work try this change the 38 pilot jet to a 42' and give the thottle 10 pumps it should start right up remember that you may have to fether the throttle a bit till warmed up. The EX is very cold blodded and worse if modded... Hope I helped this worked for me and I live in Connecticut

Not flaming...but pumping the throttle 10 times might flood it out.

JP440ex: try what mustang suggested, 42 pilot. If it has a choke, turn choke all the way on, pump the throttle 3-4 times, it should fire up.

good luck

[416exguy]

I have an 01 416 and I just stab the throttle 3 times and she fires. Even in cold ***** weather.
:macho

[zephead400ex]

What weight of oil is he running? I run 15w - 50 in the summer. Winter months you need a lighter oil, maybe 10w-40 or something of the like. Might be something to check into.

later

[JP400ex]

mines a 416 also. I guess its been ported and all sorts of other stuff. I picked up a 42 jet, its got a 38 in it. We'll see how it starts tomorrow morning.

[mustang93]

Originally posted by Aceman
If you have to pump the throttle ten times you need a bigger pilot.
You shouldn't have to pump it more than 3-4 times. Ever tried the choke?

I have never had any problems flooding it out... the choke on these things are usless I agree ten times may be overkill but it works every time and im not very paticent. the 42 pilot is perfect I dialed it in per the tech manual with a tachometer. my mixture screw is out about 1 and a half turns to 2 turns out

[2001400ex]

Since this is relatively close to my question I'm just going to post it here instead of making a thread on it...I'm going snowmobiling this weekend to upstate NY/Canada. The temperature is supposed to be in the single digits in the day time and around -20 below at night. Will a 45 pilot jet be good enough for it to start when it's -20below out? I have a 42 in now. Is it going to harm my quad riding in -20* weather? Thanks. I don't want to end up bringing it up there and then kill my engine or crack my block from it being so cold out and the engine being so hot or something then have to get ripped a new one by my dad.:eek2:

Oh yeah, beautiful 400 man I love it...

[JP400ex]

Ok. I got the 42 pilot jet and put it in last night. I went out there this morning at 12 degrees and it still will not start. Someone else told me i might wan't to try putting a stock rev box back on it and see how it does in the cold so i picked up one off ebay. I have a white bros. rev box.

[JP400ex]

Sweeeeettt!!!! I took of the white brothers cdi box and put the stock one back on and it fired at the press of the the start button. I had to turn the choke on all the way and give it a little pump of gas but it started! It would not even fire once with the white brothers rev box on it, i would end up killing the battery!

[Glamis400ex]

I was going to suggest the rev box. Mine gave me starting trouble in 50 degree weather.

Glamis

[coryatver]

Aftermarket cdi's won't turn the engine over fast enough:(

[foxmxrider55]

hey i race a 2001 400ex with everything u can do to the motor done to it. my motor has a 13.5:1 compression piston and it starts all the time in the cold....its deff not ur piston. and 10.1 compression is stock on a 400ex. i would try your carb, like the jets!, jets are a killer of power!....try the jet. but i am 100% sure its not the compression, unless ur buddy changed the crank.



Dom

[foxmxrider55]

hey i race a 2001 400ex with everything u can do to the motor done to it. my motor has a 13.5:1 compression piston and it starts all the time in the cold....its deff not ur piston. and 10.1 compression is stock on a 400ex. i would try your carb, like the jets!, jets are a killer of power!....try the jet. but i am 100% sure its not the compression, unless ur buddy changed the crank.



Dom

[MO-EX-RIDER]

my battery just died because of my rev box also.....and its only 50 during the day and 30s at night...gonna throw the stock box in for the rest of winter

[AtvMxRider]

rev boxes are a waste of money