One thing you might want to check before you tear it down, I'm not sure if older polarises have this but if this is the problem it could save you a lot of time. My scrambler was doing the exact same thing. From the box above your thumb throttle there is a wire that is covered by rubber....about halfway between the box and where it starts to go down towards the engine you might be able to pry the rubber coverings apart and there be a plastic nut, play with that for awhile and adjust that if it has one. If your machine has that it would be a good idea to check it, and it takes awhile to find the right place for it to run right, so take your time. Hope this helps ya out, good luck in finding the problem.

 

Well it turns out that the exhaust lobe of the camshaft is about gone! The valves look ok and I went ahead and pulled the cylinder off. Yikes hope im not in over my head now, looks like alot of parts. The cylinder looks nice but think I will at least hone and put new rings on. Think I should put a new piston in also? EJ

 

Check piston to wall clearance should be .001-.002 if not mic the piston and the the cylinder to see which is worn. If you plan on keeping the quad bore it and a new piston.On the cam you can get an upgraded cam from Aaen for around $170.It is for a 500 but will bolt in on a 425.To get the most out of this cam you will need to find a 40 or 42 mmcarb but it will work with the 38mm.

 

Hey Thank You! I will check the clearance tomarrow. Could you give me the link for the camshaft? I cannot seem to find it! EJ

 

Check outwww.aaenperformance.com

 

Be sure to clean out the oil tank. I would recomend pulling it out and splitting it open, it will be full of the residue from the lost cam lobe. This residue covers the bottom of the tank and can plug the oil line.

 

Hey EJ
We both had on the same time the bad experience after we bought our used playtoy.
see follow thread : Cam for exhaust valves is on the camshaft totaly completly worn

The old saying is right: when you buy used, you will buy otherone`s problem

The only thing between us: I must wait a few weeks to get my cam from the states.

By the way... The worn rockerarm I rebuilt it in a workshop where they work a lot with hard chrome facing. It cost me only 10 $


Hope our ATVīs will see the snow country verry soon.

Reinhold

 

Hi Dinogebiss, Hey sorry to hear your having the same problem. I bought my 4 wheeler not running at an auction, I was hoping for an easy fix but I knew better! I went ahead and pulled the cylinder on mine im going to replace the piston and rings. I have yet to price parts at my local Polaris dealer but did search partsland so I could compare.
I was reading on your thread about bad cams having kickback and how true that is lol. My fingers still hurt from when mine kicked back! Keep me informed on how your progress is going! EJ

 

ftwflh I looked at the site and I didnt see any $170 cams? EJ

 

SPORTY700 Good idea, I will get it cleaned out. Thanks for the tip!