just a quick note-was unhappy about getting my 400ex to idle on first start--changed main jet from a 148 to a 155--what a difference
Paul

 

What does it run like on the top end now?
I can't see the main jet affecting the idle. What else did you do?

 

The main jet should not affect idle,
it only comes in to play when
throttle is wide open.

 

I would have to agree it is the pilot jet that affects idle to 1/4 throttle and the main jet affects 3/4 to full throttle

Jera '00 400ex

 

Are you talking about your 400EX staring up in the cold is hard?

------------------
Evan Johnson 88 LT250R 99 400EX

 

Another thing to check would be the
air/fuelmixture on carb.

 

A friend and I went riding yesterday and he also had problems starting his new 00 400EX. The bike had been running good all morning but failed to start after we took a breather in an uphill sand wash. Fortunately, his problem was not related to jetting. No no good friends, the fix was very simple. You see, we sat there for a number of minutes in an uphill wash as he hammered the electric start and gave the bike a little throttle. I said: "Hey J___ (I'll leave his name out), what position is the little slide switch in? It isn't pointing to Off instead of Run is is it?" This is a TRUE story.

 

Been there done that....

Oh yeah, wait 'till you are at the top of a gnarly hillclimb, kissin the front bumper to keep the front end from goin' over, and your knee hits the slider switch.

 

I have a funny story like that. It was the second weekend that I had my '99 400EX, and I wanted to ride on Friday afternoon. It had been sitting all week, never run, and the thing would not start. I tried all choke positions and checked the air filter. It still wouldn't start. I was pissed. I was swearing at the thing, pissed off in a big way. My dad walked out and the first thing he says is, "Does it have gas?" I looked in the tank and it was dry. I flipped it to reserve and it fired up right away. Boy, did I feel dumb.