polaris sportsman 500 Motor boggs bad when i give it gas
 

Hey everyone,
I have a 1998 polaris sportsman 500. When i give it gas the motor boggs and spits and i have no power at all. It actually stalls sometimes. It does this in or out of gear. It idles great though. It has good spark. I checked the speed limiter by pulling the black wire like the book says. I completely cleaned the carb out. The diapram in the fuel pump and carb dont have any holes in them. Im at a loss. Any help would be great.

polaris sportsman 500 Motor boggs bad when i give it gas
 

Hello, As you do a search on this site I am having almost the identical problem although mine is backfiring through the card. I am actually working on this for someone and have never worked on a Polaris before.

cleaned the carb two or three times with carb cleaner and compressed air
set the valves to 006
checked the exaust lobe for wear
the jet needle was set at the bottom when I started
changed spark plug
cleaned all the connections in both handlebar sides
checked for cracks in the carb boot
cleaned the air cleaner
made sure I was getting fuel
does this with air cleaner on or off
cleaned the switches on the transmission

I finally raised the jet needle setting all the way to the top just to see what happens and it is running 50% better like this with some backfire so I ordered a new needle and main jet an am waiting for these parts to arrive. Your problem if it is not backfiring like the one I am working on sounds like a clogged main jet or the diaphram is not moving. Maybe if we both work together on this we can solve both of our problems.

I am waiting for a manual also that I ordered so my question to you is where is the rev limiter that you unplugged ? I would like to try this. This is also a 1998 sportsman 500 4x4

Rungunner

polaris sportsman 500 Motor boggs bad when i give it gas
 

I had a 1999 SP500 that did the same thing....I couldnt believe what it was. The air intake(air box lid) was actually sucking against the gas tank. The foam spacer had moved forward allowing the plastic intake to suck down when I gave it the gas. May not be your problem, but hopefully it is because it is a simple fix. Good luck.

polaris sportsman 500 Motor boggs bad when i give it gas
 

it could be your clutches are worn im thinking maybe a broken weight or cluth buttons are shot. but i would say something is out of balance.

polaris sportsman 500 Motor boggs bad when i give it gas
 

when my did this last year, i looked in my air box and it was full of water from a huge puddle i went through the day before... good luck finding it
it really seems like it isnt breathing right though, so check the airbox line too

polaris sportsman 500 Motor boggs bad when i give it gas
 

Air box is spotless

air duct was pulled out from under tank area

all tubes blown out

belt is off the clutch

have heard from others that the exaust lobe on the cam could be worn off, I looked at this and it seems to be ok, they are worn but not missing or anything like that.

polaris sportsman 500 Motor boggs bad when i give it gas
 

mine is backfiring through the carb also. Thats something i forgot to mention. The speed limiter is the black piece directly under the terminal board. its about 3x3 inces and about 3/4 inch thick . the book said to disconnect the black wire to see if this is the problem. I took the belt off so its not the clutch thing. Rungunner do you mean the diaphram in the carb may not be not moving? This is buggin the heck out of me.

polaris sportsman 500 Motor boggs bad when i give it gas
 

Does it back fire thru the carb...when going on the throttle? Sounds like a lean idle mixture. You can try to adjust the mixture screw richer, and if that doesnt help. then the pilot jet is probably partially clogged.

If the problem happens at 1/2 or better throttle, then look for a partially or fully plugged main jet.

How does the bottom of the float bowl look? Full of crusty stuff? Or dirt particles?

polaris sportsman 500 Motor boggs bad when i give it gas
 

sgajan, your lean for some reason. If this problem just started I would say you have some garbage in your pilot and or main jet. If this happened from day one you need to go bigger on the main jet. To check and see if I'm right, start the quad up, warm it up and pull the choke on half way. Give it a try and see if it bogs.
Also check to see if there is any cracks in the carb boot. Spray some carb cleaner around the boot and see if the idle increases. If it does, look for a crack or bad seal in that area.

polaris sportsman 500 Motor boggs bad when i give it gas
 

I cheked the jets and blew everything out. The carb is completely clean . Spotless. As for the idle mixture screw . There isnt one on the carb as far i can see. Anywhere. No cracks in the boot. I tried spraying carb cleaner around the boot. Didnt help. This is frustrating.

polaris sportsman 500 Motor boggs bad when i give it gas
 

I tried the choke thing also. No help.

polaris sportsman 500 Motor boggs bad when i give it gas
 

i forgot that when i choke it the bike stalls.

polaris sportsman 500 Motor boggs bad when i give it gas
 

Wow, usually when an engine bogs and then spits through the carb it is an indication of leaness.
Does this thing smell "fuelly" out the tail pipe? Could be too rich?
I just don't know?
When something like this happens to me I have to get back to basics. #1 is take a compression.
What does the plug look like?

polaris sportsman 500 Motor boggs bad when i give it gas
 

Sgajan,

Since yours is also backfiring it sounds like we have identical problems here. Don't worry too much as we will solve this problem, sometimes it just takes time. If you pull the air box off and run the machine you can look in the back of the carb to see if your diaphram is pulling the slide up as you give it gas. Check that out. move the jet needle clip all the way to the top and see if your problem gets any better like mine did. As far as the fuel screw it is on the very bottom of the carb, You can loosen up the carb and turn it in the carb boot and you will see it on the bottom. take this and gently turn it all the way in and come out 2 full turns and run the machine and come out another 1/2 turn and see if there is a difference. I am not sure of the correct setting for Polaris because I have yet to recieve my manual. Another theory is that the exaust lobe is worn so much that it is popping because the exaust valves are not opening correctly and there fore it is popping out the carb instead of the other side. How many miles on yours?

polaris sportsman 500 Motor boggs bad when i give it gas
 

This isnt my bike its for a friend i was riding with and im trying to help him fix. i have an 06 yamaha grizzly. I will check the miles on his though. It just seems so strange because it happened out of nowhere. it wasnt like it was a little at a time. I will check the diaphram to see if it is sliding. i didnt know you could see this in action. I will also check the air fuel mix. thanks. lets keep trying. It just seems so strange that this happens out of the blue. The plug on mine is black but not oily. And this is a new plug i got yesterday.

polaris sportsman 500 Motor boggs bad when i give it gas
 

I have never seen a good looking plug with my stock Hondas, They are always black and I have never rejetted because of this because I use them to go hunting and around the yard and never trail riding. They run alright for my use. I ride KTMS though and thats a different animal so plugs and jetting is very important for these. The plugs I pulled out of the Polaris are black also but like I said it is not mine so I am not too concerned with jetting a leaning this motor out. Let me know how the slide is and check to see how many turns the fuel screw was from the starting position. Tomorrow I am going to run the machine and pull the two switches one at a time off the transmission and see if one of these might be a problem, I did run it with both switches unplugged and it was worse. I will also pull the plug for the rev limiter and see if it helps.

Rungunner

polaris sportsman 500 Motor boggs bad when i give it gas
 

Im still at a loss with this one. The bowl is on the bottom of this carb. I still dont see the idle mix screw. Im gettin brain freeze. Polaris shop says they dont know. Which i can belive . The dumb A_ses. We cant be the only isolated cases with this same problem.

polaris sportsman 500 Motor boggs bad when i give it gas
 

It would be in front of the bowl in towards the intake boot, You will not see the screw as it is in a hole about a 1/4 inch, This is not an idle screw it is a fuel screw. Have not worked on mine today yet.

polaris sportsman 500 Motor boggs bad when i give it gas
 

The air/fuel mixture screw probably has a brass plug over it that needs to be removed to adjust the mixture.

polaris sportsman 500 Motor boggs bad when i give it gas
 

ok i will have to take another look at it. My head hurts everytime i go to see it. lol Has anyone talked to a service person and gotten any usefull info about this situation?

polaris sportsman 500 Motor boggs bad when i give it gas
 

I have a 500 that will replicate EVERYTHING you say here if the airbox lid is loose or off.

Did someone lose a gasket or any wingnuts? Is the airbox gasket seated correctly?

I juiced mine down with silicone grease and replaced all the wingnusts with 300-series stainless after greasing all 10 or 12 bolts. The idle smoothed out considerably, and the response has ZERO bog.

They were designed by VERY smart guys. See if the design has been altered.

If you have bad backfire through the carb an intake valve is open while the engine firses.
THAT is a serious problem. Serious. If it is mildly choking-up while th aircleaner and lid is off this may just be the nature of the beast.

D

polaris sportsman 500 Motor boggs bad when i give it gas
 

crank it up in the dark and look around the plug wire and coil and see if they are any sparks coming from them. a bad plug wire will make it backfire.

polaris sportsman 500 Motor boggs bad when i give it gas
 

Twoblackbelt: so if your air box is off or loose the motor wont even rev enough to engage the belt or move the bike?? I tried the spark in the dark thing.. I got nothing ..thanks though.

polaris sportsman 500 Motor boggs bad when i give it gas
 

Sjagan,

How is it going with your problem? FYI My machine idles great with air box lid on or off, It is not an idle problem as that is the job of the pilot jet. It has the same problem no matter if the air box lid is on or off. Do you get more backfire in reverse? I got my manual today and the new jet needle and jet and am going to try that this week and also unplugging the switches on the transmission one at a time as it is running. If none of this works it is probably one of the exaust valves not opening correctly thus backfire through the carb.

polaris sportsman 500 Motor boggs bad when i give it gas
 

Rungunner: Im not making any progress. It doesnt make a difference wether the air box is on or off. Let me know if the jet thing works. Does the book give any insight as to what it could be?

polaris sportsman 500 Motor boggs bad when i give it gas
 

If the motor is running the way you say it is..now matter what...in or out of gear...then your problem is something else...electrical. could be a sheared keyway on the flywheel, or a bad cdi or coil. could be a lot of things. if you honestly believe it is the carb...then it could have a bad seat somewhere...or chances are it is too rich somewhere... i had a 400 and the motors are identical...my problem was that it was running way too rich...i had a 175 main jet in it though, and the needle was at the wrong height.

hope this helps

Wes

polaris sportsman 500 Motor boggs bad when i give it gas
 

the motor will not rev high enough for the drive clutch to even engage..no power at all. bike wont move..reverse or forward. I just dont know what electrical it could be.. i was told that if the cdi is bad then i wouldnt get any spark at all...... but the bike does start and idle. I adjusted a needle to the highest spot on it ...didnt help though.....sigh...thanks though

polaris sportsman 500 Motor boggs bad when i give it gas
 

Yeah, it'll engage and run, but absolutley horribly.

It sounds like at idle it has enough vaccuum to keep fuel delivery going, and as soon as you take it off idle it dies, eh? Sounds like fuel delivery to me, but I'm a "hands-on" mechanic, and do not know this machine well enough to troubleshoot a trouble I've never had without the thing in front of me (or underneath me; or vice versa).

I think yer going to have to bite a bullet and find a Polaris mechanic unless you live in South Central Utah!

polaris sportsman 500 Motor boggs bad when i give it gas
 

Try running it with the gas cap off to rule out a tank vent problem, shoot carb cleaner in the carb throat when trying to rev it. That will tell you if it is a fuel starvation problem. It may have a bad stator.....

polaris sportsman 500 Motor boggs bad when i give it gas
 

powerslider..it dies if i spray start fluid in the carb..i tried the tank vent already thanks. Twoblackbelt...this bike wont even move...not even a bit..could be fuel ..but where. Thanks...this guy might have to bite the bullet for sure..i kept telling hime dont mess with anything because he is for sure a tard when it come to even tying his shoes...he tride prying off the flywheel and busted the magnets rather than use a puller...250 bucks later..he had a new one

polaris sportsman 500 Motor boggs bad when i give it gas
 

Broke the flywheel with a prybar? imagine that. Bet he broke more than just the flywheel. You've tried eliminating the ETC? Hook a test light to ground and the neg side of the igniton coil if you can, the light should flicker/flash (running) regardless of throttle opening, if it stops then you have electrical issues...

polaris sportsman 500 Motor boggs bad when i give it gas
 

powerslider:...yeh the throttle control is working..ok i will try to hook a test light to it...im just not sure what the negative side is of the coil.?..

polaris sportsman 500 Motor boggs bad when i give it gas
 

Try it on the small white wire with a blue tracer at the coil, make sure the coil is grounded good to the frame....

polaris sportsman 500 Motor boggs bad when i give it gas
 

Powerslider..ok..you said it should steady repetitive flash at any throttle? I will try and see. Thanks

Rungunner...any luck???

polaris sportsman 500 Motor boggs bad when i give it gas
 

Might sound dumb but I had the same problem with a Honda Foreman a couple of years ago I brought the bike everywhere no one could figuer it out,Iwas talking to guy at Sears(of all places)he repairs lawnmowers he tells me just drain all the gas and put new gas.Ileave there thinking what a moron,so I go home and figure why not nothing to lose,guess what?machine ran like new!give it a try you got nothing to lose.

polaris sportsman 500 Motor boggs bad when i give it gas
 

ok i will try it.... thanks

polaris sportsman 500 Motor boggs bad when i give it gas
 

had one do something simular, the guy never shut the gas off when not in use and the needle and seat went bad. filledthe cankcase with gas. Makes them really rich, check this out.

polaris sportsman 500 Motor boggs bad when i give it gas
 

Have you checked the timing and adjusted your valves , it seems like you have elimiated all the rest

polaris sportsman 500 Motor boggs bad when i give it gas
 

kerbbirds,,,,ive never checked to see if it has a drain on the crank case..it has oil injection i know but i dont remember seeing a drain for the crankcase...anyone know if it does have one on the bottom b4 i go to check on this? stumpjumper,,,ive checked the timing and it looks fine...chain is tight

polaris sportsman 500 Motor boggs bad when i give it gas
 

That's right....