Howdy,
I have a problem with my 1994 Polaris 400l, it has been running bad for a while, the last time we took it out we had to change the plugs twice as they blackend/oiled up and the bike started running rough, i've stripped down the carb and cleaned it all out, i've checked the oil pump mix ratio, the reeds are seated correctly, the air cleaner is clean.
the idle screw is wound all the way in and i still had to adjust the throttle cable at the control to get the bike to idle. low end is lumpy and the bike will not pull uphill, on a flat the bike will run smother once the bike gets moving but there's not the speed there used to be.
I also checked the bottom of the piston and there appears to be no damage there, the engine sounds ok when it idles, oh and i also checked the exhaust and that appears to be ok.
One more thing, the bike was put on it's side around 3 months ago and when it was restarted i had to turn up the idle screw so it would idle.
Today i unhooked the oil pump and put premix in the tank, also checked the counterbalancer oil level and it's not low, also the new plug was wet with oil, running it with premix gas improved the operation slightly.
Ran like a dream today, no bogging out, able to climb hills, just have to strip and clean carb one more time but looks like the problem may of been the oil pump.
It died today after running good for about 20 miles, would not start and then when it did start it sounded like it was starving for fuel, plug was pretty clean and would only start on the choke, took the carb off and cleaned out again, started it up and on full throttle it would only run for a few seconds and it took full throttle to idle, any ideas?
Many thanks.

 

couple things. first is the clutch buttons on the secondary. if they are bad it will cause engine problems. another is an air leak. having the idle screw all the way in just to create and idle is a good indicator of an air leak. check your intake boots on the airbox and the cylinder. if they look good i would check the seals on the crankshaft.
do you have the means to do a compression test? piston may look good but the rings could be wore the the cylinder could also be scored. just a few thoughts to get you going on it.

 

Thanks for the advise, not quite sure what you meant about the clutch buttons though?

 

secondary clutch buttons are in the big clutch(transmission) under the helix. they are what the helix ramps side up and down on. it requires taking apart the clutch to see and replace them. not very expensive to replace.

 

Thanks, i'm going to try the crankshaft seals first and see if that helps, there's around 4000 miles on it so it can't do any harm, the CVT side of it scares me .
Thank you both for the advice.