i have a 00 sp500 with about 350 miles. i've natice it backfiring several times. it happens when i slow down.also when i come to a stop it stalls on me, but starts right back up and idles o.k.. any thoughts?

 

had this happen to me on my 99sp335,my bolts that hold the carb to cylinder head were loose from the factory. there 2 allen heads

 

i have an expedition 425 it does the same thing when i slow down

 

did the tightening of the bolts cure the backfire?

 

yes,it was still under warranty.jughead at my local polaris shop did it after tearing the carb out and finding the carb was fine.your sucking to much air, running rich.check that out, good luck!

 

A lot of times a backfire when letting of the gas is nothing more than throttle cable needs adjustment. The sensor that shuts off the engine when throttle is frozen or stuck senses the slack of a loose cable and for a second tries to shut off the engine. There is a sleeve near the thumb throttle, pull it back to expose the adjustment wheel, its easy to figure out.

 

The adjustment screw under the rubber sleave on the throttle cable is quite sensitive. The cable adjustment screw will have to be turned slightly, and then check the thtottle before tightening the lock nut. I fiddled with mine for some time before it idled properly and didn't backfire when you let go of the throttle.

 

BACKFIRE OR POPPING ON A FOUR STROKE IS GENERALLY CAUSED BY A LEAN CONDITION.IT CAN BE AN AIR LEAK OR THE FUEL SCREW NEEDS TO BE BACKED OUT A LITTLE AT A TIME UNTIL THE BACKFIRE STOPS.A LITTLE POPPING IS NOT BAD.

 

Tmbwm...
Before you pull the throttle cable sleeve back and start adjusting it.... Pop the cover off the throttle (The ETC Switch cover...) Inside there you will see two wires going to an electric switch... You will notice as you give it the gas, the two contacts move away from each other.. Then as you let off the gas, they come back together.. THESE two contacts should NOT touch during normal operation..
Usually, after a new machine is broke in, the cable will have to be adjusted..
But, with the cover off, you can now see what is happening as you turn the cable adjuster...
As for proper specs on the "air gap".. I set mine with a 5/32 allen wrench between the contacts..
Good Luck..!!!

 

this happens to me on my 99sp500 when its not warmed up....especially in the winter when you are on the gass and then totally off