So I buy my first quad and want one of the most reliable ones out there. I picked up a new 01 warrior and there was a consistant top end knock. Back to the dealer twice for valve checks. Everything fine but still the knocking. The dealer finally tore down the top end and discovered the cylinder was not true. The dealer talked Yamaha into sending the cylinder out to have it .050 over and installed a Wiseco domed piston in it. Was this a good thing to do or will it cause problems downt the road for me if I hold onto it ? I see many people who talk about going .020 over but I havn't seen heard of .050 over before.

 

thats the worst thing u can do for a motor espically since warriors are air cooled but if it was liquid cooled then it would be a whole different story.
i got my warrior bored out then after 20 hours it blew up.
well if u got the money and yamaha will waranty the bore on your motor then do it.
2000 warrior

over 2000 invested in it
race ready
but shes in the shop now gettin rebuilt for the third time

 

You are fine. .05 is only the 2nd size over adn not that much. No power gian will be aparent except hight compression from the new piston. My 87 Warrior was bored .02 because it was way to worn out .05 was my next option only option with out a big bore. [img]i/expressions/face-icon-small-disgusted.gif[/img] IT may create a little bit of heat but that is all. I have had my bore for 6 months and it is still smooth... [img]i/expressions/face-icon-small-cool.gif[/img]

 

You will have no problem with the engine. Yamaha stocks pistons for the Warrior up to an 80 over bore. If you want to go bigger than that you would have to go aftermarket. If Yamaha offers pistons that big it's because they feel the engine can handle it. You have nothing to worry about. The Warrior is an excellent machine. Just ride and enjoy!