piston questions

[shannon cone]

not sure what brand piston, and what size rings to order. on top of pistons its stamped 25 on the carb side of the piston. it also has an F marked in pistons facing towerd the front of the ski. was told that it is one over oem yamaha pistons. when i look up oem parts finder they offer .5 and .2. whats been done is the cylinder was a part and had honed to clean it up. just want to replace the rings only becouse not very much time on motor. The ski is a 701 superjet. thanks for any help.

 

[#ZERO]

All the cast pistons have the F with an arrow pointing toward the exhaust and the .25 number would be your first bore size up from stock.

Most people don't use oem pistons when boring the engine over size so you most likely need to look for some after market rings such as Pro-X, Vertex, WSM etc.

You'll need to go with the 81.25mm rings if you actually need them or just use your old ones.

Did you check the ring end gap using a feeler gauge?

 

[shannon cone]

i did not check the gap. im only putting new rings in because it makes me feel better. so does yamaha offer a one over ring. does protec carry what i need. those guys have helped me out in the past and there great help but its past hours to call now so il call in the morning if you think they carry them. thanks for the help.

 

[SUPERTUNE]

Pro-Tec is a Yamaha dealer, so they should have no problem having them or getting them.

 

[#ZERO]

If you need them Atlantic Jet Sports has the RIK brand ring set for $19 part number 010-902-04 which are .25mm over size.

You'll need to order two sets for one engine because the price is per piston.