I've been reading these forums for a while now, and decided to officially join and see if I can get some advice!

I'm not sure if I need to temper my expectations, but I feel like my recently acquired Xplorer 500 is lacking in performance.

I bought the ATV used, and I don't think it's been ridden much since the tires are stock and still have the factory paint on them. But the bike had obviously been sitting for some time since it had varnished gas in the bottom of the tank and the carb was all gummed up.

I'm currently getting maybe 40 mph out of it on a flat straightaway, much slower on inclines. 40 is an estimate, no speedometer. It takes off OK, nothing to write home about. I've had a Rancher 350 and older Kodiak 400 walk all over it so far. I'm not sure if this is all I can expect for this machine, or if something is still amiss.

So the things I have tried to date:

Cleaned out the gas tank and carb, replaced needle and seat in carb, soaked the carb body in carb dip overnight and blew out the passages, replaced air screw o-ring, now clean as far as I can tell. The diaphragm had no holes and was tight on the slide. I did notice that the diaphragm had shrunk slightly from the recess it fits into on the top of the carb.

The primary clutch is stamped with an '06 date on it, so it is from a much newer machine. It has a blue spring with some green on it, didn't check the weights but in great condition. The secondary appears to be stock. I disassembled the secondary and looked at the helix and buttons. The buttons had a little wear, so I replaced them and polished the helix. I also replaced the spring because the secondary was shifting most of the way out under initial load during acceleration. The new spring and preload (1/3 turn on 2-2 setting) took care of that.

I tried disconnecting the rev limiter from the CDI box, and it made no difference.

I will say that the machine takes off very well in reverse! I'm not sure if it's geared differently/lower or not, but it seems to work great as fast as I dare to go in reverse.

When I rev it in neutral, it takes a while to get revved up, but it revs fairly high (I feel like most other engines I've had revved higher and quicker). Also the neutral light doesn't usually come on until revved up in neutral.

If it sounds like the performance I am getting is normal, please say so. If not... any ideas what I might be overlooking?

Not usually a butt-kisser, but Old Polaris Tech... I am on this forum because you are! Hopefully I can help someone else out along the way.

 

If you've gone through the carb and clutches as you say the first thing I would look at is the valve clearance. (.006 intake and exhaust) if you haven't already done so and especially the exhaust cam lobe! These were bad about wearing out prematurely. The wear limit on the lobe is 1.276 inches if you need to have the cam measured. If it appears worn,scored down,this could be part of the problem or the problem. They start out loosing power all the way down to where the lobe gets ground down completely and the engine will just idle and pop back. Might be something else,( could be still a clutch problem??)but these older models always scared me with the cam problems. Hope this helps. Keep us updated. I don't kiss any butts either except the old lady's ever now and then to keep her happy.. OPT

 

I visually inspected the cam while I had it torn apart to replace fluids, clean the fuel tank and carb, and grease everything. Everything looked perfectly smooth on the cams, but I didn't measure them. Intake was at .006, exhaust was a little looser but I didn't get a good reading. I would guess less than .010-.012.

The carb was varnished to the point that the needle was stuck in the seat. The fuel was brown sludge, so it was really bad, the worst I've seen. Could there be any passages or orifices that are out of the ordinary? I know the pilot (I think? the pinhole one that unthreads) and main jets were clear when I reassembled. The dip I used was the newer EPA approved kind.

Cam may be worth a second look, but nothing stuck out at me, and I was looking for this particular problem.

 

If you were able to blow compressed air through the openings,the jets are clean and open, the carb slide diaphragm spring isn't twisted up(have had that happen) sounds like the carb is ok. PLUS one thing I almost forgot is the air box missing any thumb screws or have any broken stud bolts on the box? I've also had air boxes that were and would suck air,leaning out the engine.Plus make sure the foam at the top of the clutch and air box intake tubes under the fuel tank isn't blocking the air inlet tube.. OPT

 

The diaphragm spring was messed up when i first went thru the carb, but I think I got it together correctly. It looked like a small plastic piece held the needle down in the slide, and the plastic piece was held in place by the spring. It is possible that it came loose again.

All the airbox thumb screws are in place. The only opening I saw in the airbox had a clear tube that was plugged on the other end. Filter isn't too bad.

How crucial is the float level? It's not running over, and it's getting fuel to the engine. Beyond that I'm not sure it's level.

Now that I am thinking back on it again, I was messing with the ETC box and got a big backfire that ejected the carb from its boot. Maybe I better take another look inside the carb and make sure that didn't tear the diaphragm or mess up the needle again.

From the sound of it, I should be getting quite a bit more power?

 

Make sure the carb is snug up in against the intake boot since it back fired,have had em run also with the carb almost out even with the carb brace! Yes best to recheck the carb sping,slide and slide needle too.Float arm is normally parallel with the carb body.Have the throttle thumb lever snug with hardly any slack at all on these model Sportsmans. OPT

 

Thanks OPT, I will re-check that and report back. Probably be a week or two before I make it up to my bike again.

 

All I can say is that it has the same "non" H.O 500 motor as my dads 1997 Sportsman 500 and his hits 55mph easily. There the same machine but the Sportsman has IRS rear end.

The 500 to this day is the same Fuji built motor all that makes it a H.O now is a larger 40mm carb vs your 34mm and a different higher duration cam.

 

Thanks TLC, that's some info I was hoping to get. I had no baseline to compare my machine to since I haven't seen or ridden other older sportsman 500's.

 

Well I tore back into the carb this morning. The slide was moving freely, so it didn't jam back up again. After I pulled it out for another inspection, I discovered that the diaphragm rotates freely around the slide. I think this may be the problem. I am going to try to get replacement parts today and see what happens.