I bought my first 4 wheeler a 95 polaris 300. It didn't run I was told by other people that it could be a easy fix. I got it home and worked on it. Found out it had only 30 lbs compression out of the cylinder. My fault that I bought a cheap 4 wheeler but couldn't afford the nicer ones. My question is that I need to fix the problem. I tore it apart all ready there is blow by around the piston and the bottom ring was broken and stuck in the groove of the piston. I need to know what would be my next step. And what type rebuild piston kit is good. I'm thinking I will need my cylinder bore out. Is this something that a guy with some mechanical knowledge can do because I don't have much money after buying the 4 wheeler. Thanks Joe In need of some experience help.

 

your going to have to get it bored and it requires special machinery to get it done right. take the jug to a reputable machine shop and have them mic the cylinder to see what size your going to have to get. after they tell you what size, order that oversize piston kit (ebay is usually the cheapest) and take the piston and jug back to them and have them bore it out too that piston. bore job should be no more that 100 bucks and thats pushing it big time. i would say to be on the safe side to get about 200 bucks for a complete top end kit and a bore job.

you could also just order a used jug off ebay along with a new piston and top end kit but i would guess it would cost about the same as a piston/top end kit and a bore

 

First of all take the cylinder to a good machine shop to have it measured to see if you need an oversized or standard piston. Order a OEM or good aftermarket piston and a gasket set, don't go too cheap. Make sure there are no holes in the intake boot. Inspect the carb to make sure there is not a partial plug in the main jet. Inspect the crankcase to make sure there are no stray parts or pieces of gasket left in it from dissasembley. Take new piston and cylinder to machine shop to have bored or honed. Clean old gaskets off of all parts.
Add a couple tablespoons of injection oil to crankcase to aid in startup lubracation and premix the first tank of fuel at 40 to 1. Since you don't know why the motor went down, I would recomend watching the oil level in the oil tank closely it should use about 3.2 oz of oil per gallon of gas.
If after you do all this work and it doesn't start very easily, it needs new crank seals. Let me know how it turns out.

 

Thanks for responding back so quickly. I am going to talk to a atv repair guy that does this and see what he can do and for how much. I will let you know what I find out. Is there any rebuild kits out there are any good or some out there that are no good. I should stay away from. I don't what to be screwed on getting a bad set or job done. Thanks Joe

 

If your ATV repair guy does this for you he will have final say on which parts are installed because in the end he has to guarantee his work.

 

make sure to have the head checked for wrappage as well.

 

go wiesco