Replacing stock pistons with Wiseco pistons

[DudeAbides]

I just received a shipment of Wiseco piston and rings for my 85HP. I am really surprised at how tapered they are from top to bottom.

It seems like I should be measuring my clearance from the bottom?

 

[Frank Acampora]

Don't worry about clearance! Simply install them and enjoy. Wiseco pistons are designed to have the correct clearance in a stock bore or a standard overbore. Just be sure you get the rings on the correct way. They have a 2 degree taper and are lightly marked "top"

 

[DudeAbides]

Thanks Frank. I guess I am just a little gun shy after finding that my old rings were eaten up at the exhaust ports.

I was concerned that there would be too much clearance at the top of the piston.

But I guess you are saying that Wiseco knows what they are doing and its no cause for concern

I did note the mark on the top of the rings.

Thanks, Jason

 

[Frank Acampora]

I have probably replaced 50-100 Wiseco pistons with no problems. In fact, while some piston rings were close to the maximum end gap, I can't think of ant where I needed to adjust the end gap.

Remember: The top of the piston gets full combustion heat and expands significantly more than the skirt. Thus when cold, the top has a lot more clearance than the skiry.

 

[smoedog]

Not to hijack but. What is the end gap for the rings? And how far down the bore do you normally measure? Im about to replace one of my pistons in my 96 force 50 and need to know the specs for the rings.

 

[Frank Acampora]

For Wiseco pistons in larger engines end gap is a maximum of .016. To be honest, I forget the minimum but the specifications come with the pistons.

I don't know what the smaller engine specs are. You measure at the top of the cylinder where heat will be the greatest thus piston and ring expansion is greatest also,