Hey everyone! new to the forums and am in need of some help.

I just bought a 2000 sportsman 500, it starts up decently, e-start is not working properly but the pull cord works perfectly. Once its started it idles and revs fine in neutral but once its in gear and i start giving it throttle 35-70% it starts to backfire and it losses all power but the motor doesn't die out and i just let it sit for a couple of minutes and i can drive for about another 2 minutes before it backfires again.

Help me please?

also is it normal for the motor to kick out if i turn on the choke to full when its idling?

 

I'd pull the valve cover and check out the exhaust cam lobe. Sounds like how most would run with a flattened lobe.This involved the early Magnum 425 models and Sportsman and Scrambler 500s from 1996 to 2000 models. Her's one posters pics of his cam and symptoms he had from his Scrambler 500.http://forums.atvconnection.com/pola...d-cam-pic.html If the exhaust cam lobe is ok,then it could be simply needing a carb kit, might have a fuel tank vent kink or blockage causing a vapor lock condition until it gets another build up(gulp) of air,or a weak fuel pump problem. I'd start at inspecting the cam first.

 

okay i will take a look at the exhaust cam, also the speedo doesnt work do i just swap it out or do you know how to fix this?

 

If the speed indicator doesn't work it could be as simple as mud around the speed sensor cap located on the right front caliper. If this area is clean then probably the hall effect sensor has shorted out. This was a common problem. Item #42 Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

 

sweet thanks OPT, By the way, I went and tested out my atv today to see if it would backfire again, and while riding it my bother noticed that my headlights and brake light were flickering on and off while i was driving and while it was backfiring. Is this a common issue with the exhaust lobe? The previous owner did tell me it was taken into a shop for the backfiring and they told him it was electrical issues.

Also do you know where I could find a wiring diagram for the ATV?

 

Check that all electrical connections are tight especially the battery and ground wires and that it's charging 14 volts back to the battery. Here's a link to a pdf service manual that includes electrical schematics.Index of /ORV Manuals/Polaris/Sportsman/1996 - 2001 Pretty common issue with the cam lobes,as I would check the cam out for sure. But like you mentioned it could be an electrical problem you're having.The schematic also shows resistance specs on the stator and coil along with other trouble shooting help.