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Polaris 500 Popping through carb

19K views 26 replies 11 participants last post by  j_gregory_ 
#1 ·
Ok all you Polaris Gurus. I have a 2000 Ranger 6x6 500cc. It was running fine, shut it of and when it was started back up 5 minutes later it started popping through the carb.. It will start and idle and you can rev it up a little if you press on the throttle very gingerly. If you mash the throttle it will just pop and die. If you go easy it will run and pop but not past a certain rpm. Here is what I have done thus far.

1. Fresh gas and cleaned the carb.
2. Adjusted the valves.
3. Checked compression. Its 125lbs. (I dont know how this is supposed to happen but it takes like 3 compression strokes to get there)
4. Checked my timing marks at flywheel and cam. They seem to be where they are supposed to be based on other posts in this forum.
5. Re adjusted the valves just to make sure I didn't do it wrong the first time and had a mechanic double check my work.

I am totally stumped on this one and so is my mechanic friend. Any help will be greatly appreciated.
 
#9 ·
Ok all you Polaris Gurus. I have a 2000 Ranger 6x6 500cc. It was running fine, shut it of and when it was started back up 5 minutes later it started popping through the carb.. It will start and idle and you can rev it up a little if you press on the throttle very gingerly. If you mash the throttle it will just pop and die. If you go easy it will run and pop but not past a certain rpm. Here is what I have done thus far.

1. Fresh gas and cleaned the carb.
2. Adjusted the valves.
3. Checked compression. Its 125lbs. (I dont know how this is supposed to happen but it takes like 3 compression strokes to get there)
4. Checked my timing marks at flywheel and cam. They seem to be where they are supposed to be based on other posts in this forum.
5. Re adjusted the valves just to make sure I didn't do it wrong the first time and had a mechanic double check my work.

I am totally stumped on this one and so is my mechanic friend. Any help will be greatly appreciated.
sounds like my 04 400 when the fuel pump pooped out. have you checked fuel flow?
Checked the fuel flow and it seems great.
 
#11 ·
Check electricle connections at kill on switch main fuse and ignition mabye wiggle them see if it helps those problems wont throw a code also wiggle wires to TPS and map sensor those will usually throw codes though just my. 02 hope it helps ignore tps n map if ur carbed
 
#13 ·
That is the second story i have read here where a Polaris was running fine then on a restart they did not run well and it was due to worn cam lobes.

One shop owner told me the factory oil pressure system is very low (shop manual states 12-20 PSI) and if synthetic oil is not used or the engine is permitted to idle it will stave for cam lube causing the lobes to wear off.

It seems this does not happen perhaps as long as a Polaris with the low pressure oil pump is moving (engaging the clutch) but when it is set parked and running it can wear off the cam lobes.

I think the rest of the engine is OK typically and it is mainly the cam that suffers making it a simple top top end fix. Some go with the newer higher lift cams maybe like in the HO line. While this can add power it would also mean there was more metal to wear away before the lobes would be too worn to run some day.
 
#14 ·
Mine did have a lot of idle time because we use it for yard work. It always seems like it is the exhaust lobes that wear. My intakes were like brand new.
you will always see the cams for sale with the exhaust rockers but hardly with all three. I bought them all and did it complete because I don't want to do it again.

I think it has something to do with the compression release ball on the exhaust lobe. I recommend changing the oil 2 to 3 times a year, using Polaris oil or Mobil 1.
 
#15 ·
At least you got it going. I guess low RPM's was not a problem when designing snowmobile engines since the top end got oiled due to the high RPM's. :)

A local ATV shop said there is an after market stuff that can help make sure the oil pressure is high enough and they fit them with physical oil pressure gauges. That may cost more than a cam however. :)
 
#16 ·
the exhaust is the one that wears because there is only one lobe opening two valves so it has to work twice as hard
 
#17 ·
#19 ·
I have a 2000 sportsman 500 that has similar issues. When it is in neutral it will idle great then you get a quarter way through the trottle it will cut out and bog down. It does the same thing in gear (low and reverse) doesn't want to pull itself in high. I rebuilt the carb, cleaned the tank and has fresh gas in it. Do you guys think I might have the same issue or does it sound electrical ? Thanks in advance.
 
#20 ·
fastford406 it could be the worn cam issue another posted and it could be electrical.

The 'project' 2002 Magnum 325 bogs and dies if you put it in any gear and give it gas but we expect it is due a spun bearing (it has rod inserts and not roller bears like a 500) from being ran without motor oil when the past owner blew an oil cooler hose running down the road.

What kind of compression PSI do you have. We caught the compression tester on sell at Harbor Freight for $20 which was $5 off regular price. The adapter doubles as a way to use the air compressor to pressurize the cylinder so you can test for the source of the compression loss.
 
#24 ·
I was thinking that to but if your exhaust never opened then how are you still getting flow out of your exhaust. Just checked my compression it is at 125 psi. Is there a good way to check the cam without just replacing it and hoping for the best?
 
#25 ·
yep look at it take off valve cover and cam chain cover remove rocker and inspect cam or for the simplest way for a rough idea just pop off valve cover and watch and see how much its moving your rocker......id still suggest checking those electrical issues i mentioned i had the same symptoms and thought it was the cam and it was electrical
 
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