Model is Polaris Xplorer 500, 1997
Problem - No accleration, no speed, no torque, Overheating a LOT

Things i did already:
Made sure fuel pump worked
Air filter fine
Cleaned Carb, cleaned jet
Changed Engine oil/filter
Fuel to carb is fine

Things I noticed:
The day before yesturday, she had barely any power. Then yesturday she was Fast and speedy, now today she has no power at all. This has been going on for a little while, but slowly shes been having no power more then power.

There is a bit of a dark mark around the top edge of the motor, where the Gasket is. Might be a dead Gasket? There is no white smoke coming out of the exhaust, no black smoke. Shes just got no power and overheats a lot.

It takes 1 minute of driving for her to overheat, when I drive through water there is a LOT of steam.

So she overheats a lot, and the power goes from barely any, to a lot, to barely any over the course of a day or two.

What could this be?

(Edit) On the Cylinder head, the Dark mark is overtop the Gasket #11, on the right side (the side closest to you on the picture) Could this be the cause?
http://www.bikebandit.com/assets/sch...34_163_161.gif

 

I would check the spark plug. If that looks good, then I would do a compression test on the cylinder.

--- Just thinking out loud, but it sounds like the engine timing might be off...which is really weird for an ATV. ---

Good luck...and hopefully you will get more responses.


biz

 

The #11 in the picture is only the valve cover, wont loose compression, maybe oil, they do like to vibrate the bolts out on the 500,s make sure all the bolts are in the cover,take the thermostat out of it and see if it stil gets hot, located on the left-side in a housing, 2 bolts, the radiator hose thats highest on the engine hooks to it make sure the water pump is working, they usually will leak if there going bad. You can check thermostat while its out, put in a pan of water and heat it up, if you have a meat thermometer it should open at 180- 190 degrees. Also make sure Radiator is spotless, Ive had to remove them to get them clean, the back side gets plugged.

 

Also check for a air lock, if the top rad hose feels hot and full but the bottom hose feels cold and empty then there's a air lock in the cooling system that needs to be bleed out.

 

Alright, I believe i fixed the cooling problem. Thanks guys . turns out the 2 tubes that go from the engine, to the engine, connect at the very top of the radiator. When I opened the Radiator cap there wasn't any fluid at the very top where the tubes connected, so there was no flow of fluid. So I filled her up via the radiator cap to the very top, and closed it.. now she runs cool. The Reservoir doesn't seem to have the suction anymore to fill the radiator, going to have to fix that..

New symptom, She still has no power and when I rode her earlier she started to hiccup, I'd crank that throttle, she'd be barely going, engine would barely rev, and she would occasionally go "puh"..

I can't reach the Spark plug, too far into the motor, need a different ratchet to get ahold of her but i'm thinking it might just be the spark plug? Thing is, she had power on and off for the past month, but now it degraded to basically no power at all.. spark plug?

thanks fellas

 

How many miles on it? have you always used 0w-40 oil? maybe you have a worn exhaust cam lobe, do a search on this site, it happens on the 500 motor but the usual symptom is power lost and back firing out the carb. Another power lost problem is worn buttons on the clutch.

 

Shes pretty old, i've ridden her quite a bit so her miles are high, not entirely sure the exact number though. Not sure what the fella before me used for oil, but I filled her with 0w-40.

When i put her in neutral, the same thing, her rpm climbs just a bit and thats it, same in all gears.

I haven't a clue as to what an exhaust cam lobe is lol, the carb doesn't backfire thankfully. Took the air filter off, rev'd her, and again she had no power and the nothing was happening with the carb (thankfully)

 

Here is a good post about the cam Polaris Camshaft - The Garage Journal Board

But dont panic,do the plug change first and make sure the air filter is clean as well.

Also I hear worn secondary ramp buttons cause power loss. but the motor should still rev out in neutral if that was the case.

 

Well she still has no power, she rides, but i can't go up a small hill unless im in low, and even in low she barely makes it.

but the main symptom that gets to me is that one day i'll have FAST power, then the next shes a slow as a sloth.. and she is still slow as a sloth.

Before all i had to do is fill the gas tank to full and she had power, now that doesn't work anymore. This led me to believe it was something in the fuel line.. i connected the gas tank directly to the Carb, same ordeal.. cleaned the carb, same ordeal..

I took the plug out, it was just covered in black, chunks here and there.. so i cleaned her off, she still runs the same.

i'm at a loss again, One pointer is that power used to come back by filling to tank up to full.. now that doesn't work.

 

But a new plug in, not save it.