Polaris 325 Magnum Not Running

[PupATV]

HI! I am new here to the forum and was wonder if if I can get help with my ATV here?

 

[Russ from MN]

If you would explain the symptoms, you might get some comments! My first 4-wheeler was a 425 magnum, had lots of trouble with it, got rid of it and bought a Honda. Still driving that 26 years later with no problems, Polaris was pushing them out of the factory without testing for reliability.

 

[Mule Meat]

Never saw or heard of a 235. Know that the 325 had a lot of fuel problems back in their day.

 

[Rystoltenberg11]

HI! I am new here to the forum and was wonder if if I can get help with my ATV here?

We never had a Polaris ATV, just the sidexside and the RZRs. But before the side by side we had Yamaha banshees for ranch bikes. I used to look forward to cattle work then.

 

[Rystoltenberg11]

.

 

[stevieb49829]

HI! I am new here to the forum and was wonder if if I can get help with my ATV here?

I have a '99 500 magnum in the shop right now. Good, dependable machine. Mostly plows snow. It died a couple of weeks ago. I've learned how to check the entire electrical and ignition system. There is a good Polaris ATV forum online. I have a new stator coming for it. steve

 

[PupATV]

Never saw or heard of a 235. Know that the 325 had a lot of fuel problems back in their day.

Whoops I meant 325

 

[PupATV]

Whoops I meant 325

Fixed it

 

[PupATV]

Okay so here's the deal: So I have been working on this Polaris 325 Magnum 2001 that I got for free and it had a aftermarket carb in it with the needle and seat shot...So instead of buying a rebuild kit I bought a new OEM Polaris carb abd stuck that in it..Still not right: It bogged really bad on higher throttle and when going up and down hills....So then fall was turning into winter and this spring I have started to work on it again and I thought to myself...Maybe its the ignition coil and so I replaced it with a aftermarket ignition coil and it doesn't bog when going up and down hills anymore but it stills doesn't run that great and doesn't have that much "punch" and I can't run it with the air box cover on...It seems like its running rich but there is no black smoke ect and I have the carb set a factory settings......I did a compression test today and got 55 psi...but then I opened the throttle and did a compression test and it bumped up to 175psi. Hope you guys can help!
-pup
PS. I also replaced the CDI box and no difference....

 

[PupATV]

So any ideas welcome!...I am at the end of my wits!

 

[Rodney51Cub]

Check the intake tube going into the air box. I worked on a Honda that had a dirt dobber nest in the intake tube.

I can't run it with the air box cover on..

 

[PupATV]

Check the intake tube going into the air box. I worked on a Honda that had a dirt dobber nest in the intake tube.

Yeah I already checked that

 

[used red MN]

Hello PupATV, welcome to YT! I don’t know about anything specific about your ATV never worked on one. On most small engines the initial factory settings are just a rough starting place. Not running with the air box would indicate to me a rich mixture. So I would screw in the main jet to see if that improves it. On the other side I don’t see anything about checking the fuel filter or the supply from the pump even though it is likely a gravity flow system from the tank above the engine. I think the idea of searching out an ATV forum would probably get you more accurate and specific information for your machine.

 

[PupATV]

Hello PupATV, welcome to YT! I don’t know about anything specific about your ATV never worked on one. On most small engines the initial factory settings are just a rough starting place. Not running with the air box would indicate to me a rich mixture. So I would screw in the main jet to see if that improves it. On the other side I don’t see anything about checking the fuel filter or the supply from the pump even though it is likely a gravity flow system from the tank above the engine. I think the idea of searching out an ATV forum would probably get you more accurate and specific information for your machine.

Thanks! so the main jet in the specific carb is a set size not an adjustable one buy it doesn't have a needle plunger that regulates to flow of the fuel...That I have set and the leanest position. I did just notice today that the boot between the engine and the carb is badly cracked so I will replace that and get back to you guys after I fix that! Yeah, I have been on those forums too...

 

[stevieb49829]

So any ideas welcome!...I am at the end of my wits!

So I think what you are saying is that without the airbox cover, it runs like it should? If that's true, check the neck of the airbox cover for any obstructions. Does it have a new air filter in it? If not, try blowing through the air filter to see if you can sense any restriction in the filter. If there is ANY restriction to blowing a breath through the filter, replace it. Then on to your carb: I'm assuming you replaced the aftermarket carb with the OEM slide throttle Mikuni? The gold-colored "pot" on top of that carb has a diaphragm that sucks the slide and needle out of the primary jet when you open the throttle plate. If that diaphragm leaks, or the slide is stuck it will really hamper throttle response. I know it's not easy to get to the carb, but once the gas tank is off, you can easily remove the cover of the diaphragm and inspect it for leaks, and to make sure the slide is sliding easily. Also, if you have the carb out, pull the main jet out and make sure the hole is completely open. I use a fine sewing needle to pass through the orifice in the jet a couple of times to make sure it is completely open. You don't want to ream it out, just make sure it's completely clean. steve

 

[PupATV]

So I think what you are saying is that without the airbox cover, it runs like it should? If that's true, check the neck of the airbox cover for any obstructions. Does it have a new air filter in it? If not, try blowing through the air filter to see if you can sense any restriction in the filter. If there is ANY restriction to blowing a breath through the filter, replace it. Then on to your carb: I'm assuming you replaced the aftermarket carb with the OEM slide throttle Mikuni? The gold-colored "pot" on top of that carb has a diaphragm that sucks the needle out of the primary jet when you open the throttle plate. If that diaphragm leaks, or the slide is stuck it will really hamper throttle response. I know it's not easy to get to the carb, but once the gas tank is off, you can easily remove the cover of the diaphragm and inspect it for leaks, and to make sure the slide is sliding easily. steve

No even without the airbox cover it doesn't run very good but with the airbox cover it almost doesn't run at all! Yeah the airfilter could very well be causing problems as it been soaked in gas sat in ran ect.. Iam not sure that it's a mukuni, but yes it's got the slider thingy. Actually I have this thing totally stripped down until i get the problem fixed so it's super easy for me to get to the crab...But Polaris seems to want to make things hard to work on and put a big metal bar that welded to the frame right over the back of the carb so you really have to fight to get it in and out. The diagram is band new (Basically) so I doubt there is any problem there.....

 

[stevieb49829]

No even without the airbox cover it doesn't run very good but with the airbox cover it almost doesn't run at all! Yeah the airfilter could very well be causing problems as it been soaked in gas sat in ran ect.. Iam not sure that it's a mukuni, but yes it's got the slider thingy. Actually I have this thing totally stripped down until i get the problem fixed so it's super easy for me to get to the crab...But Polaris seems to want to make things hard to work on and put a big metal bar that welded to the frame right over the back of the carb so you really have to fight to get it in and out. The diagram is band new (Basically) so I doubt there is any problem there.....

You can't hurt it to pull the 4 screws and check over the diaphragm and the slide. There's a long coil spring inside that you need to be careful to keep straight when you reseat the cover. I put just a very thin layer of RTV silicone around the very edge of the diaphragm so I knew it was sealed against the body of the carb. I don't have a diagram for the air passages, but check it over closely for any small holes that might have some obstruction in them. Think about what might be stopping the air pressure from changing under the diaphragm when you open the throttle plate. steve

 

[PupATV]

You can't hurt it to pull the 4 screws and check over the diaphragm and the slide. There's a long coil spring inside that you need to be careful to keep straight when you reseat the cover. I put just a very thin layer of RTV silicone around the very edge of the diaphragm so I knew it was sealed against the body of the carb. I don't have a diagram for the air passages, but check it over closely for any small holes that might have some obstruction in them. Think about what might be stopping the air pressure from changing under the diaphragm when you open the throttle plate. steve

Yeah i know what's in there...I have only had this thing apart like 10 times!

 

[PupATV]

You can't hurt it to pull the 4 screws and check over the diaphragm and the slide. There's a long coil spring inside that you need to be careful to keep straight when you reseat the cover. I put just a very thin layer of RTV silicone around the very edge of the diaphragm so I knew it was sealed against the body of the carb. I don't have a diagram for the air passages, but check it over closely for any small holes that might have some obstruction in them. Think about what might be stopping the air pressure from changing under the diaphragm when you open the throttle plate. steve

Okay yeah, I will check that Monday and put some sealant in there.

 

[stevieb49829]

Okay yeah, I will check that Monday and put some sealant in there.

just a little bit along the edge of the diaphragm.