99 XC 500 no power, back fires.

[hattrk4me]

I need some Ideas.

I just bought a 99 XC 500 SP 2200 miles on it. It’s having problems in the low RPMS btwn 2500-4000. at idle it kinda coughs and sputters, at 3500 it starts to back fire. The exhaust is thick with fuel. Once I can break the RPMs it seems to run OK until around 50 MPH, at this point it seems to loose power and will take another ½ mile to reach 65MPH. It tops out at around 68-70 MPH. This sled should easily do 85.

The Carbs have been taken off, cleaned twice with in the last week. Ive drained the tank and did find about a table spoon of water in the fuel. Then drained the carbs.

The clutch has a light blue spring with 1056 weights, seems hvy to me but the dealer confirmed the are the correct weights.

could this be an ignition issue?

[gjk1970]

How are you cleaning the carbs is my question? If you are just using carb cleaner that may not be enough. You can purchase a gallon of solution from your local auto parts store that you soak the carbs in and it boils them out.I just bought some myself and it runs around 25.00.(NAPA) But since there was water in the tank you may want to also replace your fuel filter and drain your engine block should be 10 m.m. bolts down under your exhaust manifold. I found out earlier this year that Polaris if you do not shut off the fuel it will continue to flow (gravity) and flood out the motor. Also do a compression test after you have drained the motor. Have you replaced the spark plugs? You may have a bad spark plug as well. When the sled is running use a spray bottle with water in it and mist your spark plug wires and see if you get them snappin. If they are snapping you may want to get some new ones. Just a few ideas to try.. Hope something works for you..

[hanson]

I bet you have low compression on one side. Just do a quick check with a gauge or your thumb over the spark plug holes.

Otherwise it sounds like you are running with the choke on. Could possibly be stuck somewhere.

Just a couple more things to check.

[hattrk4me]

a dealership has cleaned them twice.

I'm pulling around 92-95lbs per cylinder for compression.

[hattrk4me]

never heard of the "ol'spray the plug wires with water" trick. I'll check the wires.

[shortfatguy]

not an expert but i think you should have around 125 psi might want to check with a dealer to find out what the compression should be

[gjk1970]

Yep compression WAY too low..You have a bad cylinder in there..

Sorry for the bad news.. But you should have at a minimum 115 in order for sled to run decent.. I have seen them run with as little as 105 but not real good...