I have a 1998 Sportsman 500, and the master cylinder seems to be messed up. The plunger that sticks out of the mastercylinder seems to be stuck in, or somthing. The lever just flops in and out without hitting the piston assembly. It is full of fluid, and everything looks good. The foot brake still works. Anyone ever had this happen? I would think if the piston was stuck in, and the system is full of fluid, the brakes should be locked up, but that is not the case. Any help here would be great.

 

My guess is the seals around the piston on the master cylinder are shot. If you don't get a good seal on the piston its not forcing any brake fluid down the lines when you squeeze the lever. Just like an engine, the rings on the piston have to contact the walls of the cylinder evenly to create compression. I'd replace that piston/plunger and you should be all set.

You can buy the piston itself without having to replace the whole master cylinder assembly.

 

It is odd that the piston wont return back out though.

 

what does it feel like when you pull the piston back out with your fingers? Is it hard to pull out or does it seem to just be flopping around in the cylinder?

 

Do I have to buy the special installation tool to get this done like it says in the service manual? Or is it not really required?

 

I havent been able to pull it back out.

 

isnt their a spring in side as well that pushes the piston back out? if so maybe its broke. just a guess.

 

Yes, there is a spring that is supposed to push the plunger back out. I will try and take it apart tonight and see what is going on. The service manual says I neen a piston installation tool to reinstall the piston and seals. Has anyone done this before? And do I need the tool?

 

I've done it on a motorcycle and didn't need any kind of tool, but I've never done it on a Polaris ATV. I'd take it apart if I were you and see if you can get by without it. Alot of times the dealer tool makes things easier, but you can get by without them with enough patience and resourcefulness. Good luck!

 

i seem to remeber some of them w/ a snap ring to hold things in but im not sure about them.