My Sportsman 335 acts like it isn't getting enough fuel when I let off the throttle after riding a little piece. I idled it up some;didn't help. I ran new fuel through it; didn't help. The plug is good, boot is good, I just don't know.When it's moving it runs like a champ, but when I let off the throttle it just chuggs and chuggs.Any ideas? It's getting old.:I
BushHog

 

I noticed what seems to be the same thing on my brand new 500. It will actually stall because the it seems like the idle is set too low, but I never changed it. It will also backfire when I let off the throttle. It does this intermittently. ??????

 

Mine backfires too! What the heck is going on with our quads?

 

Check the ETC switch on your throttle control... and re-adjust it... SOmetimes, after a new machine is broke in.. THe cable stretches a little and whats happening is your switch is trying to shut down the engine...
THis is a good place to start.. Thats usually the problem..

 

Hey...I'm not the only one! I have infrequent backfiring on my SP500 EBS as well, happens if I drop the throttle to slow down, as its slowing down, kabang. Cute during deer season, but kind of makes you wonder. I raised the idle speed, had to, because quad was stalling out with the EBS as the engine neared idle. Troublesome when you hit the bottom of a gully and punch it to start up the other side. I guess I expect a lot out of my Quad, maybe a little more than the average. But when it dies when you need power its frustrating.

 

In my experience backfiring is usually caused by a lean mixture. Possible causes, an air leak between the carb and the cylinder. With the motor idling, take a propane torch (not lit of course) and direct the propane towards the seams between the carb and the engine. If the motor increase rpm you have a leak that needs to be fixed. Another possible cause is incorrect jetting. One other thing is check the timing.
Hope this helps.
Dave Formstone
98 SP500 EBS.

 

SWAC i think you need to check your jetting
maby find somone that rides where you do with the same quad and see if they changed theirs

BTW my kodiak runs GREAT hehehe

 

I got two SP 500's (99) from the same dealer on the same day. One backfired and stalled from the start, the other has run perfect. Also, the one that backfired also ran about 2-3mph slower than the other. I never checked the carbs to see where they were set, I'll bet they weren't the same. (I've had to rebuild one since so It wouldn't make sense to check now) My dealer did mention the idea about the mixture being too lean.

 

Thanks, since my SP 500 is now in the shop, I will call to have the carb checked out. This forum has got me thinking so much about performance and general mechanics, maybe I should have pursued my life long goal of slaving on an engine assembly line instead of living in the outdoors and riding around on this beautiful spinning ball of dirt.....

 

The Polaris shop manual says that whenever you adjust the idle you should also check and adjust the throttle cable, if necessary.

I found this out after taking the carb out of my wife's 99 SC500 twice because it wouldn't idle and backfired after accelerating and then letting off the gas.

I set the pilot screw according to the manual, set the idle screw and then made a very minor adjustment to the throttle cable length. Problem solved.

I had read over the part about checking the throttle cable a dozen times. Wish it had sunk in the first time. It would have saved a couple days of frustration.

[This message has been edited by deskbound (edited 01-17-2000).]