400ex problem, please help!!

[400exRider12345]

hey,
I have a 99 400ex. I just got it last week. I ran it 3 times in weather above 50 degrees. It ran perfect. It was great and fast!! I just took it out today, and it ran bad. It was like 35 degrees out, but it was weak. It tok forever to warm up, and i could like hear the engine rev more than the pipe. It didnt have much power at all either. It just reved and went like 65 percent power. I'd be on it, and hear the engine revving instead of the pipe really. Is this a jetting problem? What could this problem be? I hope its not expensive, please help, please.

[400exRider12345]

somebody has gotta know, please help

[NJ300ex]

It could be your revbox and your jetting is definatley lean.

[400exRider12345]

i have the stock rev box on...i'll go check my plug, the seller told me that it runs a tad rich

[CranMan]

Try draining some fuel from your float bowl, there may be a little water and junk in the bottom of the bowl. I'm pretty sure there's a screw you can loosen that will drain the bowl through the draintube. Also, make sure there's not any water in your airbox, if there's a little in there it can get sucked into the engine at higher rpms and make the quad seem like it's missing or lacking power. Just some things that have happened to me!

[400exRider12345]

hey,
I think that might be the problem. I have an outer wears cover, but i put the stock lid on and washed it. I shot it down with a hose. Maybe i got a water problem. Could I just turn the gas off and run the engine till everything is drained? Would that do it? And then turn the gas on and it'll be fine. Please let me know what to do.

[CranMan]

I'd have to look at my Ex again to be sure, But I think there's a screw on the carb that you loosen to drain the bowl. As for any water you might have gotten in the airbox, just pull that clear tube thing from the bottom of the airbob, if there's water in there it will drain into that tube. I'll look at my quad after work for the location of the carb bowl drain screw......

[400exRider12345]

ok thanks a lot, i'll wait for your reply

[CranMan]

I forgot to look last night:( But I'm sure someone else around here knows!!! I've got college after work tonight, so i won't be able to check tonight either....sorry!

[Braff1]

There is a screw on the bottom/left side of the carb. It is counter-sunk. loosen that screw and you should see gas run out the tube next to the swing arm.

[400exRider12345]

ok,
thanks a lot, I'll see what i can do tonight or tomorrow

[400exBro]

I think there is also a bolt on the bottom of the float bowl(17 mm rench) just losen it and all the gas will come out fast.
If your going to clean it, you will probably take it all apart(plastic, fuel tank etc..) and take off the carb, buy some carb cleaner and spary it every in the carb and take a air compersor and spary all od the stuff out of the carb so it is dry.

Also check your choke setting. I think my 400ex makes the same noise you described when I forget to turn the choke off.

Good luck!!

[400exRider12345]

ok, thanks a lot. I wanna do all the things i can that will be the easiest to do first. I am not that experienced and I dont wanna end up taking the whole quad apart and not knowing how to do anything

Sounds like the clutch might be slipping, make sure your using the right oil. I like honda's 10-40 moly blend. I've heard full synthetic makes the clutch slip worse.

[400exRider12345]

thats what is sounds like to me, when i was riding, i was like damn, my cutch needs to be totally djustd. The lever is like loose and can move a couple mm either way, up or down. But, it makes that sound in neutral also. If it were the clutch, wouldnt it only make that sound while moving in gear? I'll check and see what i can do.
Thanks

lemme know if you have any suggestions