starting problems

[400ex07]

I just bought a 2007 400ex and it never seems to start good. It stalls often and sputters until its warm. I have seen older 400's start right away and never stall out. It also makes a whistiling noise sometimes. does anyone have any suggestions on how to fix my problem? I put better gas in it and it still didnt fix the problem.

[c.mcd]

the whislting noise is the turbo on it...kidding.....mine sputters when its cold just like yours but id say its a jetting problem from the factory....dont know what the whistleing noise is

[BigMike]

Same problem with mine. According to everything I have read, changing the pilot jet to a size 42 will alleviate the problem.

Mike

[BigMike]

Same problem with mine. According to everything I have read, changing the pilot jet to a size 42 will alleviate the problem.

Mike

[jrafter]

i have an 05 and it did the samething.......just change to a 42 pilot and 150 main jetts and add a K&N filter.

What a change.....starts right up and runs great.

it was so easy too.......hardest part was getting the 5 plastic fastners out......i used zip ties to put it back together.

[Speed_MDS2]

The starting issue is normal, they are quite lean at idle from the factory. The whistle noise is also normal every 400 I've seen does that. You start it and as its warming up you start to hear a "whirling" sound for a few minutes. Nothing to worry about.