2003 sportsman 500 HO not starting-backfires
The sportsman will not start for me. It turns over no problem using the starter. I’ll crank it for a while then eventually make a loud pop noise. The air seems to come through the carb. i got it to run briefly yesterday using starter fluid. That was short lived. I could not get it to start after that using starter fluid. one weird thing i noticed. After trying to start it for a while using the start button the engine just wouldn’t move. I forgives this was due to me drawing on the battery. So i went to use the pull start. It was solid, would not move. After a decent amount of time passes i use the cord and it moves again. -I checked compression,80 psi. -it has a spark, replaced the spark plug -i checked fuel flow. It’s not a heavy flow but it’s moving the gas. I cleaned the fuel pump. Just dusty no mud. -i removed and cleaned the carb. -I removed and cleaned the starter. One of the brushes was stuck. -battery is good. About a year old. -Air-filter is nice and clean -new gas -i pulled the valve cover off. Everything moves, no metal or grinding noise -i checked the fly wheel and it’s proper mounted (no sheared key) I’m about to remove the engine and start looking inside. Any help would be greatly appreciated!! |
Sounds like lobes worn down on the camshaft. Throwing it out of time.
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I was starting to look into the timing. With worn lobrs would mean cam replacement? |
Yes. Happened to my boss's 04 700. Same symptoms, backfiring through the carb and all. Was told that the metal that the cam was made out of was a softer metal, and wore down easily.
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Thank you for the info. I’m gonna get the motor out today and peel it apart. |
Any recommendations for a good engine kit ?? Other than Polaris ! |
The soft cams were mainly an issue on the 1996-2000 Sportsman 500s, before they made the 500 H.O.s with a different cam. It's rare to hear of anything outside of that range having have soft cams.
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Ok, I took it apart and measured the lobes. They are all with in spec. I noticed heavy carbon on the piston head and cylinder head. I’m assuming it’s normal but figured i would mention it. Should i check anything else prior to putting it back together. |
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