Hello all and thank you in advance for your advice!

What I have is a hand-me-down 1999 Polaris Sportsman 500, it sat for about 4 years, outside, partially covered, in the elements. That should give you an idea of what I'm working with!

It would start, but would not throttle up as to instantly bog down. If I pumped the throttle I could sometimes get it to rev to maybe 3/4. Typical of a carburetor issue it seemed to me after sitting outside for half a decade.

I'm relatively lazy, and wasn't going through the rebuild process, so I just bought a new Carb, fuel pump, spark plug, air filter, fresh gas.

After getting it all done, getting the fuel pump primed and fuel going to the carb it started! However, more or less the same issue is happening. Only difference is I can semi-ride the thing on half choke.

What I failed to do is, open up the new carb and check the jets for sizing.This could be the issue and I'll go through the process of removing it and checking it maybe this weekend. For now let us presume the main jet is either 150 or 155 (for now since I am getting some other potential ideas from you guys)

I also didn't set the air screw, and I am waiting for my angled adjuster tool in the mail as I lost my old one I used on my motorcycles. but would that make "THAT" much of a difference in being able to get off idle? Screwing it in would make it run richer or leaner?

Questing about the the notches on the needle, moving it down toward the tapered end would richen it up correct?

I read a lot about the cams being eaten up, however I don't think this is it, as I can rev it near full throttle with very little bogging if at all while on half choke, I would think if the exhaust lobe was gone choke wouldn't matter it just wouldn't exhaust properly.

Also read potential electrical problems but the same goes with my theory on the cam, electrical malfunction won't care about choke I don't believe.

I have figured out it runs lean as all hell, with the air box off (no I cannot get the airbox to completely seal, it's borked and broken 6 ways from sunday) if I spritz the air filter with starter spray or carb cleaner, the throttle response off choke is nice and snappy.

A lot of this really in my mind anyway, aims to the new carb being jetted incorrectly, please let me know if you agree and if there is anything else you think I should check. Thanks again everyone for your help.

--Dick

 

Seems I might have some sort of small air leak on the plastic intake manifold tube. Though I can't see anything with the naked eye, when I spray around it the RPMs definitely go up/down etc. Are these things prone to failure?

 

Hope you are not a Gov'mt employee.
Same story with me. 2003 trail boss 4stroke 2WD, all original, sitting for 12years.
After wasting time cleaning & testing & adjusting & "fixing", I bought new fuel pump, all new tubing, filters, on-off valve, carburetor, air filter, battery, spark plug.
Not to mention, two brake masters, oil cooling fan, seat, paint, tires, etc, etc. Since it seems like you must remove the engine to change the tail light bulb,,, might as well do everything 100%.
Now it starts instantly, idles quiet & smooth, no over-heating. Rev the engine, and it dies. Riding is possible with both hands,,, one to throttle, the other on the choke. Its goes FAST !
Carb float OK, Jets OK, slide-needle @ richest setting. (Same settings as old carburetor).
The next problem-check-point is a flat-cam-lobe. I checked compression and vacuum. Dry&oiled compression tests over 100psi. Carb vacuum pegs my gauge !

The 'store' grease-monkey says " its too old, i dunno ? " Wrong answer. I'm pushing 78 (not daisies) and I'm getting a bad feeling with this machine. I had hope to get it fixed before Xmas.
I guess Mr.Lance must have owned a Polaris !

 

That reminds me ....
We had a very old 4cyl tractor with an up-draft-carburetor that would back-fart up thru the oil-bath air cleaner and set itself on fire.
Throw a old dirty wet towel over the air cleaner, and it would suck the fire out, and keep on chuggin'.
One time, it never caught fire because I had forgot to remove the old towel.

 

That was it !!! The old air filter had had been replaced by a cheapo motorbike sponge thing.
There was not enough 'resistance' for the stupid vacuum carb to open the slide. The choke was simply dumping gas into the engine, until the slide slowly opened.
A new auto-quality fiber filter, and voila ! The engine revs perfectly off the idle.
I'm ready for a drag race !

The EMPI filters fit my old VW sandrail 4-solex-carbs. They are paper/wire with a foam sock. I removed the sock to fit the Polaris air box.