I have an 04 KFX 400, the problem is it runs as if it were starved for fuel when in gear but not nuetral. I pulled the carb and cleaned it but the prob persists. I will sit on it and rev it and its smooth but as soon as I put it in gear even if the clutch is in it sputters, it doesn't stall and it idles fine. Pleas help.

 

sounds like you have a short in your electrical

 

thanks, could you give me a hint as to where to start looking.

 

do you have any mods ? any at all?

 

just a pipe.

 

so your saying you put on a pipe but you did not rejet ?

 

the pipe's been on the bike since I bought it, it ran fine at first, I don't know how long the pipe was on before I bought it or what else might have been done or not done after the pipe was put on.

 

how long have you have you had it ,as I'm leaning toward the valves be out of adjustment,dirty air filter even to much oil on the filter can cause problems.

 

I have only had it a couple of months, the air filter is clean. If the valves were out wouldn't the problem be evident wether in gear or not?

 

If you plan on keeping the quad the best investment you can make is to get a good O.E.M. or Haynes Service and Repair Shop Manual , it will pay for itself with the very first complete serving of your bike ; do a plug check to determine if your air/ fuel mixture is right ! Check the color of the spark plug tip , if it's a white/grey color you are runing lean ; if it's black you're rining rich the color should be a tanisih /brown color when you have the mixture correct ! And don't count out the valves being off spec. if you've never had them adjusted , and if the guy before you never had them adjusted they could be off spec.'s ; i've seen them run good in newtral and bog down and stall out under load before ! And it could be caused by dirt/trash or water in the fuel tank , and it could also be from carbon build up in the combustion chamber as well ; get a clear container and remove the fuel line from the carburator and drain the fuel from the tank into the clear container to see if water/dirt or trash is in the fuel ! If the gas look's and smell's right check and adjust the valves if thy're off spec's , mix some Sea Foam in the jug of fresh gas ; but before you pour the mixed fuel into the tank i would splice the fuel line and install a clear fuel filter between the gas tank petcock/on,off.reserve fuel valve and the carburator ! Then pour the mixed fuel into the gas tank and rung the quad untill you've burned the mixed fuel , to make the job quicker you could get a can of Deep Creek in the spray can ; it's the same stuff as the Sea Foam only it come's in a spraycan ! You can remove the airfilter and spray it diirectly into the carb , it will burn off the carbon build up in the combustion chamber quicker this way ; just follow the direction's on the can's and don't freak out when it start's smoking ! It will smoke while it's burning the carbon deposit;s , and it will stop smoking when the combustion is cleaned out ; you can get the Sea Foam and Deep Creep at most auto parts stores like , Auto Zone Advance And O'Reillys Auto Parts Store ; i got the Sea Foam at O'Reillys Auto Part's Store for $5.99 + tax this stuff is the best i've ever used ! I bought a 88' GMC Jimmy 4x4 MPV that from a used car dealer who told me the engine and drive train had been rebuilt and only had 87 thousand miles on it since the rebuild , but after i drove it about 75 miles it would blow out a puff of whitie/blue smoke when ever you had to stop at a traffic light and had to wait 30 to 60 seconds for the light to change ; when you gave it the gas to go it would blow the puff of smoke ! It would clear up as soon as you got going ! Two week's after i got it , i tried to start the engine and it jumped time , i had to save up the money to buy the part's ; it took me over 6 month's to buy the part's ! The Jimmy had almost a full tank of gas when it jumped time , so i poured a 16 oz. can of Sea Foam in the tank to keep the gas from going bad ; i got 2 of my brother's to rock the Jimmy to mix up the gas and had to let it sit up for the 6 month's untill i could but the part's ! After i got the part's i tore it down and replaced the timing chain and gear set , i also had to replace the starter and flywheel ; the i set the timing with a borrowed timing light and removed the cap from the throddle body so i could turn up the low idle speed ! I started driving it again , and it started smoking again only worse this time ; after i used a half tank of gas i went to the Race Track Gas statin and filled the tank with fresh gas ! On the way home i had to stop at this traffic light that take's 5 minute's to change green turning arrow , and this time i looked in the driver side mirror to see the smoke ; but this time there was no smoke ! So i drove down the highway to a small town about 30 mile's from my home ! On the way back home i stopped about 12 time's and let it idle for 5 minutes before giving it the gas ; and still no smoke ! It has been smoke free for over 6 month's now ; so the Sea Foam cleaned out the combustion chamber and stopped the smoking ! The Sea Foam was the only thing that could've claeaned up the combustion chamber , so i use it for everything now 2 and 4 stroke engine's ! ............