need help with 4 wheeler!

[summit02]

I just got a 1994 polaris 400 2-stroke for free in great shape but it hasn't been run in a while. I started it up but it won't idle and the throttle response is bad but once you get the rpms up it runs great. I took apart the carb and cleaned everything but nothing. any ideas? and i don't know if this would have anything to do with it but it seems to heat up faster than normal. Please help supposed to take it out this coming weekend for a little ride.

 

[RMKRAZIE]

This is a snowmobile post fyi. But I'll go along with it. I have similar problems with my 05 sportsman 500 ho. It doesnt idle with out holding the throttle just a little bit and at about 3000 rpms is spits and spudders and will die. I took apart the carb and the clip that holds my needle fell off and the needle just fell and was sitting in the jet. I fixed it and i thought that would fix it. Wrong. it still does this and i cant figure out why. input for myne would be great too.

 

[Kraven]

I just got a 1994 polaris 400 2-stroke for free in great shape but it hasn't been run in a while. I started it up but it won't idle and the throttle response is bad but once you get the rpms up it runs great. I took apart the carb and cleaned everything but nothing. any ideas? and i don't know if this would have anything to do with it but it seems to heat up faster than normal. Please help supposed to take it out this coming weekend for a little ride.

Did you drain ALL the old gas out and replace with FRESH fuel??

New spark plug?

Possible broken reeds. I replaced a set of stock broken reeds in a 1994 POLARIS SLT 750 watercraft and a 1996 SL900 POLARIS watercraft with similar symptoms, and they were only 3 seasons old when it happened.

Try adding "sea foam" fuel treatment to the fuel, sounds like snake oil but I've had success with it cleaning out carbs/injectors.


Hope this helps.

 

[summit02]

I tried sea foam and drained the old gas and just added sea foam this weekend. I didn't check the reed but will have to check that out tomorrow.

 

[IQR]

4 wheeler trouble...

I know you said you took apart the carb, but did you remove the needle valve assembly, the little do dad under the floats, usually clipped in or held with a spring, or by the float assembly itself. you need to remove this and blast breakleen through the fuel line nipple and make sure good flow is there.
Also when it heats up real fast, that usually means there is a lean condition on the bottom end, you need to richen up the mix on the air screw. I would reccomend getting a service manual for propper procedures on that carb.
also inspect the pilot jet real good this could cause it to run like crap on the bottom, if the hole, or holes are clogged. hoe you got rid of all the old gas, and blasted out the tank, and looked at the petcock if it has one. anyways I hope this helps.

 

[IQR]

wheeler trouble........

I betch its bad reeds, almost 100%

 

[mtnclimber19]

If it hasn't been run in awhile, take the exhaust off and check that it isn't plugged with a mouse nest or anything. We also used to have a lot of problems with the mufflers plugging up with mud because the outlet points down and the tires would throw it up in there, they usually have a clean out plug on the bottom. good luck!

 

[svensdream]

I have worked on tons of these 4 wheelers, the most common thing that I found is that the needle and seat wound "square out" from the vibration of the motor and make it idle poorly, the other common thing is the front of the skirt on the piston would break off, this causes hard starting, poor idle and throttle response. It was really common for this to happen, most machines would blow the skirt right out the exhaust without causing any other damage, If run really rich I have also seen the muffler get clogged with oil residue. One other thought, If the air intake pre filter under the seat is clogged or pinched off by the seat that will also cause it to run poorly.

 

[Old700]

like said above. Reeds are worth looking at as well as the plug on the bottom of the carb. It rubs on the transmission and will start to leak very slightly, and when it does, it will run the way you describe. I just did a top end on my xplorer 400 2 smoke on the weekend, and have owned a few. One more thing to look at is the vent line from the carb, all my 400's have the vents running very close to the pipe, and if the one from the carb melts shut, you get a symtoms kinda like your describing as well. Good luck, those 400's can rip if tuned up right.