OK, I'll try to keep this as short as possible. I bought a used 2000 Polaris Xpedition 425. It's a 4-stroke, 5 speed model. This is a SHIFT model. Long story short, water got into the magneto housing through the pull start hole and shorted out the stator. This is how I bought the quad. Now, I've sent the stator out and had it totally rebuilt with new coils and whatever else. I put it back on after I cleaned and dried out the housing. I lined up the timing mark, and set the gap on the pick up per the manuals specs. I plug all of the wires back in, fire it up and it idles nicely. Problem solved right? Well I go to give it the slightest amount of gas and it pops and backfires and will not rev past idle at all. Not even the slightest amount past idle. It will even stall if I rank on the throttle too much. It almost sounds like a reverse limiter stuck on but guess what....this unit don't have one! It's a shift model so the reverse is limited by the gear ratio. So, what did I do....Changes spark plug. No help. Took the carb off and totally went through it. It was spotless. I verified that the diaphram was opening the slide. Jets are clear and it's getting gas. I verified this by testing the fuel pump, plus I poored gas diretly in the cylinder with the same results. I even cleaned the tank out and put fresh gas in. Next I made sure my intake was not restricted. I checked all carb boots and air filter. Same results even with the air box totally removed. Next, I hear stories of exhaust cam lobes going bad. So, I checked the valves and verified this and the cam has the same size exhaust lobe as the intake. They all look to be in very good shape. Next, I check all switches on the bars. All test OK. So, I go to the electrical section in the book. I test the ignition coil, throttle safety switch, stator and all electrical things I could think of. All test out within spec according to my service manual. What do I do next....I bought a brand new CDI to make sure this was good. Does not help. I can't check the timing per the manual because I need to rev it to 3500 rpm. I would but it won't rev past idle. I checked the timing at idle and it is right with the middle timing mark (30 degrees I think). I am about ready to throw this quad in the river so if anyone can help me before I pull my hair out, I would GREATLY appreciate it. I am very mechanically inclined and work on motors almost every day, but I can't figure this one out. I've exhausted all options I can think of. Are there any other safety switches or things I can check? Remember this is not the auto/snowmobile clutch model. Please help! Thanks!

 

Have to narrow it down to whether it is a fuel problem or timing.

While it is idling, give it a squirt of starting fluid (ether). If it just speeds up, obviously needs more fuel. If it stalls or B Fires, its likely timing. There's good info on this forum, hang in there.

 

Sounds like you may still have a problem with stator. Are you sure the flywheel key is still good?

 

The flywheel key is kind of chewed up and wore, but it still holds the flywheel in place fine. I tested the rebuilt stator and it seems to ohm test according the the 450 ohm per coil check. Is it supposed to be timed at max advance at idle? I did't think so, but I can't retard the timing much more. I've moved the stator plate each way and retested it with the same results. Thanks for any further help....

 

If it's chewed up then it might allow the flywheel to shake or vibrate while the engine is running. My .02... I've had sleds that did this and one time it was a fuel issue - the other time it was a wiring issue.I'd check and make sure that the grounds are all good and that there are no bare wires anywhere... brake light, head light, etc. Does it have a battery? fuses?

 

Now that you mention brake light, the brake light wires are cut and there is a bad connector back in that area that I figured was just for the light. The connector has a red/black wire, but it looks as if it just goes to the battery and that's it.

 

OK guys/gals. I spent 1/2 day going over everything on this quad I can think of. I started with the basics. Checked valves and cam timing as well. Spot on. Here's is where I think my problem stems from. My ignition timing at IDLE (around 1,000rpm) is at FULL ADVANCE (30 degrees). My timing light through the hole reveals the 30 degree timing mark. Why would this be fully advanced at idle? It should be more around 8 degrees at idle or so. Am I wrong on this? Can anyone verify this with there machine? What controls the ignition advance? I've moved the stator plate as far retarded as I can and it is right at 30 degrees advanced at idle. This don't make sense to me. Any help is great. Thanks!!