Hi All,

I am getting ready to install my 107" pistons and going through the process of checking all the end gaps for the rings.
The top ring and 2nd are all good. just wanted to check if the expansion ring should have the same end gap as the two control rings. Checked the manual but it never mentions the expansion ring. Only for positioning on the piston.

What do you guys do?

Any help is always appreciated.

Thanks

Rob

 

As long as your ring sets were all from packaging that was not broken you should be good... No worries. You should be able to tell with installation on just how they roll onto the piston. Just from memory, I don't have a manual in front of me but, I think there is end gap clearance charts. I am assuming your using all new parts, correct?

Start at the lowest ring land of your piston, oil rings then your top compression rings. Make sure to follow the manual on your end gap staggering. Your end gap clearance on your oil rings isn't the critical one anyway. Your top two compression rings are the important ones.

Hope that helps

 

Here's Harleys recomendation

http://www.harley-davidson.com/en_us...ts/-j00975.pdf

 

Thanks Taggs,

Its the expansion ring (wavy one) I have a concern about, rather than the oil rings or compression rings. It touches ends when on the piston and when checking in the bore. Is this correct of should its gap be the same as the oil control rings around 0.0200 - 0.0300 thou?

Rob

 

Thanks UL. Great info...I would only point out that is a tech sheet for reringing a used set of pistons. Wear limits shown is good to stay within allowable tolerances for worn parts for that.

New pistons and rings you should be good to go. My best gage has been just how the rings roll on. The oil rings when in there e should be snug on the piston but movable as a unit. Your top two compression rings should move freely. Check there end gap if you like but, like I mentioned if they fir without falling off or to tight to move, your good

Good luck...

 

The spring under your oil rings should be closed at its ends and move freely before and after topping with the two oil rings. When the two oils rings are in place over the spring this becomes a unit. It should still move on the piston a unit. Just don't let the two ends of that spring overlap.

 

Let us know how it goes...

 

Will do. They all move freely on the piston. Just worried about it tightening up once in the cylinder and forcing the expander to over lap. Or is that not possible?

Rob

 

I have never had to gap oil control or expander rings. When the control ring gaps are staggered, the expander and top/bottom rings act as a unit to wipe the cylinder walls. I don't believe the OP has an issue but without seeing the rings installed, really can't say.

 

As long as the oil rings and spring are free to move as a unit your good. I lube all the rings with engine oil just before assembly. Things will better find home once the jug is put in place. You are using a ring compressor for assembly right??