purring like a kitten

[ggodfreyX]

So after researching info on this forum my 2005 400ex is on point. I bought the ATV at the end of last summer which was bogging down on acceleration in 1st and second gear. It would seem like it was out of gas and then take off like a bat out of hell. I changed the pilot jet from 38 to 42 and put in an after market fuel screw so I could adjust the mixture without any tools. I was initially concerned because of the 125 main jet with a stock pipe but it runs amazing. I ended up at 1 and 3/4 turns out. The only mods are a K&N air filter. I ride at about 7000 feet elevation. I hear a slight tick so I will check to make sure the valves are in spec but it runs like a champ!

[cheater13]

There is normally always a ticking noise with the 400ex's. But throw on a slip on pipe and you will like it even more! :devil:

[trailrider894]

The tick is pretty normal for a 400ex, It would be a good idea to check out the valves and make sure they are all adjusted to spec. Also, my EX had an engine tick, that I fixed by swapping out the stock timing chain which is known to stretch out, with a timing chain from a CRF450, I believe it was from an '04. I did that and replaced the timing chain tensioner.

[ggodfreyX]

Good to know about the ticking. I will put a pipe on it next year. It's my wife's quad and she needs to work her way up. Before she had a trx250ex which had enough power for her but she wanted a manual clutch. The front end is a feels a lot lighter on the 400. We have our annual Moab trip coming up in May so I'll see what she does with it. I ride it also but have my son on there with me so I have to take it easy. I have another question about 6 vs 4 ply tires but I think I'll start a new thread for that as others may like info as well.

[whyzee]

Wow that 125 main seems too lean even for your elevation

[ggodfreyX]

Originally posted by whyzee
Wow that 125 main seems too lean even for your elevation

I thought so too but it does not seem to run hot. I called the guy I bought it from and he did not change the jetting, it was put on my a dealer here in CO. I posted the question on a separate thread, "Is This Some Kind of Joke? 125 main jet". The general consensus was that it was where it needed to be.

[chevymanrick]

ggodfreyX if you don't mind me asking where did u buy the aftermarket fuel screw from? I can't find them anywhere.

[ggodfreyX]

Originally posted by chevymanrick
ggodfreyX if you don't mind me asking where did u buy the aftermarket fuel screw from? I can't find them anywhere.

It was tricky to find. The part I ordered did not specify it would fit the 400ex but it does. I had a suspicion that Keihin carb parts would be somewhat interchangeable since the jets were the same for my Honda dirtbike. I took the pilot screw off of my CRF 450X and it fit perfectly on the 400ex so I ordered this;
http://www.rockymountainatvmc.com/p/44/54/213/1151/568/13581/Tusk-Fuel-Mixture-Screw
Please note that my stock D shaped screw was set to about 2 and 1/8 turns out and this screw dialed in at about 1 3/4. This may or may not apply to your TRX. It's well worth the 12 bucks!

[chevymanrick]

Awesome thanks man