05 400ex is a tempermental PITA

[mmartin]

I have had a few 400ex's now so the jetting in my climate/elevation is nothing new to me. I have a 99 400ex and now an 05 400ex. Both have aftermarket slip ons, 42 pilot, can't remember the mains but thats not where my problem lies.

On the 05 its still a pain to start unless the engine is already warm. I had an 04 with the same problem and my 99 did as well. As soon as I dropped in the 42 pilot, moved the clip and adjusted the A/F they were perfect. The only difference I can think of is the needle. I put the 42 in, adjusted the A/F out 2 3/4 turns as a starting point and have been playing with it since. I just cant seem to get it right. Once the bike is running its perfect. It doesn't backfire, flood or bog. It just won't idle to warm up unless you sit on it to catch the rpm's as they drop. I can turn the idle up but I have to turn it up way too high to keep it running. I'm kind of anal about my bikes running perfect.

Has anyone else had this problem? Is it worth it to spend the 65 on the dyno jet kit so I can get the new adjustable needle or have others been successful without it? I'm not trying to be cheap I just dont want to replace parts that don't need to be replaced and end up with a bigger headache afterward.

One more thing, anyone know where I can get an extended A/F screw for the 400ex? I have checked bikebandit, Rocky Mountain, Ebay etc none seem to have one.

[hornetgod13]

Mine is the exact same way. I also have a 42K pilot in and my fuel screw is at 2 1/2 right now. I've been fine tuning it between 2 and 3 turns.
It just won't idle until it's warmed up unless you keep playing with the throttle. If I turn the idle up it will keep running but, once it warms up the idle is too high.
I finally gave up and accepted it. I jump on and ride it as soon as I start it so it's not that big of an issue for me but, I feel your pain.
I have a DynoJet adjustable needle installed in my 2006 400EX and it won't help your idle issues. I have the clip adjusted to the third slot down. Not certain if it was really worth it but, it's nice to know that the mid-throttle range is still adjustable if needed.
There are no extended fuel screws made for stock 400EX carbs. I've searched and all I can find are ones made for after market FCR carbs.

[projectram]

My 05 is the same way. A pain to start in the cold and when its been sitting for a while. I always thought it was just mine but i must be not.

[js600]

i got an extended fuel screw for my 05 from cycle gear. it cost 22 bucks or so. it makes it so much easier to adjust. if i can find the package i'll post up the brand. also it does fit and work perfectly with my stock carb.

[mmartin]

Anyone try a 45 pilot yet? I think I'm going to give that a shot and see what the results are. I will swing by the local shop one day this week then post the results. Thanks for your help/input.

[hornetgod13]

Originally posted by js600
i got an extended fuel screw for my 05 from cycle gear. it cost 22 bucks or so. it makes it so much easier to adjust. if i can find the package i'll post up the brand. also it does fit and work perfectly with my stock carb.

I searched Cycle Gear's website and couldn't find it. What kind of a fuel screw was it? It would be nice to know. That would be helpful for the rest of us. I'd like to get an adjustable fuel screw but, I've hit dead ends everytime I try to find one for a stock carb.

[440challenger]

I had the same problem on my 06!
While everyones quad was idiling warming up with the choke on id be sititng on it keeping it running or running back to keep re starting it.SOOO annoying. I was going to install the 450r carb but ended up putting the whole 04 trx 450r motor,carb,rad etc into my 400ex. Best thing i ever did.

[mmartin]

I dropped a 45pilot in the bike today and didnt even need the choke to start it and its about 30 degrees outside. I might need to put the 42 back in for the summer but that is definetly what is needed for the winter months. Thank you to everyone for your help/input on this one.

[Ruby Soho]

Im not sure what my jet sizes are right now, (it has a dyno jet kit installed). Im waiting till I go to install the HMF pipe to see what it is, but my 400ex starts up just fine in the cold. I start it on no choke just to get it on, and then put the choke about 3/4's way up. i let it sit there for a couple minutes and then take the choke off and it idle's fine. I then ride it around slow in 1st gear, and then slowly get on the throttle.