Polaris Sportsman bogs down with air box installed
Nov 29, 2010 | 11:30 AM
#41
Weekend Warrior
Joined: Oct 2009
Posts: 6
Likes: 0
tominfl,
As you may have seen from my post above from nearly a year ago, I had a Sportsman with this issue and did manage to finally solve it so don't give up!
These carbs are real sensitive to pressure balance and so, when you have it all hooked up, there can't be any air leaks at any of the connections or around the air box lid.
Does it run well with nothing attached to carb (air box, tube, etc)? If yes, make absolutely sure you have no restrictions and that the air tube from the air box is clear. As mentioned above, it's real easy to have part of the foam spacer inadvertently block part or all of the inlet up under the tank. If it still doesn't run well without anything attached to the carb, clean the carb like Kerbbirds suggested.
As kcaves mentioned, it's possible that the exhaust lobe on the cam is worn down. I know the Sportsmans had some trouble for a while with that and a people were finding the lobes looking rather round.
Good luck and keep us posted!
As you may have seen from my post above from nearly a year ago, I had a Sportsman with this issue and did manage to finally solve it so don't give up!
These carbs are real sensitive to pressure balance and so, when you have it all hooked up, there can't be any air leaks at any of the connections or around the air box lid.
Does it run well with nothing attached to carb (air box, tube, etc)? If yes, make absolutely sure you have no restrictions and that the air tube from the air box is clear. As mentioned above, it's real easy to have part of the foam spacer inadvertently block part or all of the inlet up under the tank. If it still doesn't run well without anything attached to the carb, clean the carb like Kerbbirds suggested.
As kcaves mentioned, it's possible that the exhaust lobe on the cam is worn down. I know the Sportsmans had some trouble for a while with that and a people were finding the lobes looking rather round.
Good luck and keep us posted!
May 13, 2011 | 03:47 PM
#42
Weekend Warrior
Joined: Jan 2011
Posts: 3
Likes: 1
Similar Issue
I have a similar issue with my 97 Magnum 425. The only difference is that if I put my hand partially over the air intake hole after everything is put together, it will rev up again. Does anyone else have the same thing happen? Its like its just getting too much air. As long as I just block a little bit of the air intake hose, it will rev up and run just fine...
May 14, 2011 | 06:33 AM
#43
Weekend Warrior
Joined: Oct 2009
Posts: 6
Likes: 0
Fixed the bog down
I thought I had it fixed. But she played up again, so I whent through the forum & made a list of all the things that cause this trouble. I spent the next 10 hours in the workshop checking every thing on the list & in the manual. I even striped my other Polaris magnum 425 of all the parts that might be playing up, I put another new plug & air cleaner as a starting point & went through the list, the last thing on my list was the timeing, I set it 4 years ago & I didn`t think it could move. But that was it, the bloody timeing was retarded. I retimed it & it ran rich [140 jet] , played with the jets leened it out with a 130 jet then worked my way up to a 137.5 jet. Now she runs like a champ. There is NO ONE FIX . you just have to go through everything to find out why your quad won`t run. I hope this helps . thanks Darren
Oct 10, 2011 | 01:00 PM
#44
Weekend Warrior
Joined: Oct 2011
Posts: 1
Likes: 0
david jones i had that problem i removed foam from under tank runs awsome saw this po
Working on a 1998 Polaris Sportsman 500. This thing had a couple of unusual problems that baffled a few good techs. Got the starting problem, previously posted, repaired and now starts like new.
I tested this ATV with the air box removed, ran like a scalded dog at high speed, pulled some impressive wheel stands, awesome power and idled like a Cadillac. Put everything back together and it bogs badly in neutral or in gear, won't rev up.
Removed air filter, same problem. Removed air box, ran like new again.
Replaced the carb with a direct factory replacement. Float level correct, choke and throttle cables adjusted to specs. I removed the air intake tube from the air box, checked for obstructions, there were none. About 2-1/2" on the filter side and 1-1/2" on the carburetor side. I can rev the motor to 3k or 4k RPM's, slip the air intake tube over the carb air inlet and the motor practically dies. Remove the intake tube and the RPM's pick back up almost immediately. The original carburetor did the same thing and was replaced because of this.
Is it possible for jetting to be this far off on a factory replacement carburetor?
Anyone have any ideas?
I tested this ATV with the air box removed, ran like a scalded dog at high speed, pulled some impressive wheel stands, awesome power and idled like a Cadillac. Put everything back together and it bogs badly in neutral or in gear, won't rev up.
Removed air filter, same problem. Removed air box, ran like new again.
Replaced the carb with a direct factory replacement. Float level correct, choke and throttle cables adjusted to specs. I removed the air intake tube from the air box, checked for obstructions, there were none. About 2-1/2" on the filter side and 1-1/2" on the carburetor side. I can rev the motor to 3k or 4k RPM's, slip the air intake tube over the carb air inlet and the motor practically dies. Remove the intake tube and the RPM's pick back up almost immediately. The original carburetor did the same thing and was replaced because of this.
Is it possible for jetting to be this far off on a factory replacement carburetor?
Anyone have any ideas?
May 24, 2013 | 09:59 AM
#45
Weekend Warrior
Joined: May 2013
Posts: 6
Likes: 0
Hello All, I just recently started having the same problem. Throttle response is slow engine boggs, backfires and sputters quite a bit enough I cant go over 10-15mph.
After rebuild of the carb, new timing chain and some cleanup the sportsman 500 (1997) had perfect throttle response and ran like new. I even attempted to put a new camshaft on but after close inspection the OEM camshaft looks perfect. However this bogging issue happened suddenly about a week ago (only 60 miles after all the work). After about a 1/4 throttle the engine boggs, sputters and backfires.
Looking at this picture I found out I did not have either #18 (with the mini filter) or #28 hooked up. This morning I just hooked up #18 because i remember where it was. But through this #18 breather line I think something got into the carb and I need to re-clean it!
But I can not find what is #28. One website says it a LINE,BREATHER,120CM,SPL But i do know where to find it? Anyone have any ideas where to find this other breather line, Where does it come from?
Thanks!!
Refer to Image Below
After rebuild of the carb, new timing chain and some cleanup the sportsman 500 (1997) had perfect throttle response and ran like new. I even attempted to put a new camshaft on but after close inspection the OEM camshaft looks perfect. However this bogging issue happened suddenly about a week ago (only 60 miles after all the work). After about a 1/4 throttle the engine boggs, sputters and backfires.
Looking at this picture I found out I did not have either #18 (with the mini filter) or #28 hooked up. This morning I just hooked up #18 because i remember where it was. But through this #18 breather line I think something got into the carb and I need to re-clean it!
But I can not find what is #28. One website says it a LINE,BREATHER,120CM,SPL But i do know where to find it? Anyone have any ideas where to find this other breather line, Where does it come from?
Thanks!!
Refer to Image Below
May 24, 2013 | 11:28 AM
#46
Polaris ATV Expert
Retired and loving it!
Retired and loving it!
Joined: Jun 2008
Posts: 24,350
Likes: 44
From: North Texas
You have two vents that go to the air box. One is the oil tank vent tube at the very top of the tank,the other is the engine crank case vent tube at the front of the engine with the filter on it.
May 24, 2013 | 11:22 PM
#47
Weekend Warrior
Joined: May 2013
Posts: 6
Likes: 0
I have checked out the air system. everything looks fine. It didn't run much better when i had the air filter off. Maybe the throttle seemed a little more responsive.
I'm thinking the timing may be off. 65miles after the timing was set and I was fooling around in a river bed pushing the engine more than I ever have and that's when it began the bogging and backfiring. Now I notice at idle there is more black smoke out of the exhaust.
I'm thinking the timing may be off. 65miles after the timing was set and I was fooling around in a river bed pushing the engine more than I ever have and that's when it began the bogging and backfiring. Now I notice at idle there is more black smoke out of the exhaust.
May 25, 2013 | 01:08 AM
#48
Polaris ATV Expert
Retired and loving it!
Retired and loving it!
Joined: Jun 2008
Posts: 24,350
Likes: 44
From: North Texas
Had problems on some of these old ones if any of the molded in bolts in the air box broke to where the lid wasn't sealing properly. Would bog down when giving it throttle.One other thing you can check is the pulse(pick up) coil behind the recoil cover for any dirt or trash that could be causing problems.Stator timing is preset and the flywheel is timed on a woodruff key on the crank.If you check the pulse coil you can also pull the flywheel nut to see if the woodruff key may have sheared which could move the flywheel a little out of time. The cdi handles the timing advancement. I still wouldn't over look a cam problem if it still backfires through the air box,plus if you haven't measure the exhaust lobe against the intake lobes for excessive wear.
