I have a Honda 350 Rancher, I had the cylinder bore at a professional machine shop .020, bought new pistion and rings, machine shop fitted pistion to cylinder, has 3 hours on it, and it smokes, ring grooves are lined up opposite each other, why is it smoking when it wasnt before?

 

Either rings haven't seated(should after 3 hrs) broken ring or possible piston was set up too loose. The chart from the Rancher manual shows the cylinder to piston clearance is even tighter than Polaris 4 strokes.
Cylinder-to-piston clearance Standard: 0.015 0.045 (0.0006 0.0018)

 

If atv didnt smoke why was cylinder rebored and repistoned?

 

Was wondering when someone would notice that. I assume he wanted more power but it would have been better to sell the Rancher and buy something with more power. Ill probably eventually do that myself, sell my Rancher and buy something with more power but not ready to just yet. Better to leave anything stock, its just more reliable that way.

 

I did all that to get more power, I also got a gear reduction about a year ago, and I'm a she not a he. Ranchers are just reliable, we have more than one fourwheeler I didn't want to do that to a new fourwheeler, the fourwheeler is bad and will go threw just about everything.

 

I forgot to mention in the first post, the pistion is a high compression one, we found out what was wrong with it the machine shop messed up the cylinder, its oval shaped instead of round so oil is traveling threw, when the pistion goes up and down.

 

Then I'd take it right back to them and have them bore it to the next over piston and eat the cost on a new piston and gaskets.They didn't take the egg shape out and probably bored it with too much clearance. Problem on a lot of 4 strokes is that even some machine shops allow too much clearance. Again the factory specs shows piston to cylinder clearance between 0.015-0.045 mm (.0006-0.0018) which is tight!

 

We took it back, should be fixed tomorrow we knew we didn't do anything wrong putting everything together and when we measured everything it was wrong

 

Hopefully everything works out better this time. Sorry I just assume everyone is a he in here unless their name would indicate otherwise. Ranchers are pretty solid machines. I guess I can understand trying to get a little more power but I'll probably leave mine alone unless it actually does start smoking. Mines just a 2x4 though. I bought it basically because it was the best machine I could get for the amount of money I wanted to spend at the time. The only modification mine has is a K&N air filter. I keep thinking I'll upgrade but I kinda like it. Probably keep it for a while. I have other things I plan on spending money on instead anyway.