Hello, I bought a SE 110 bolt on kit (tire shredder) for my (2015) 103 fat boy and went to gap the Piston rings and read the little instruction paper that was in the piston box just for the hell of it. Well Im glad I did because I was about to set the first ring at .018 to .02 (4x.0045). The instructions say the first ring gap should be set at .010 to .016.
I got two guys in my club who work at harley shops and they both question this, as do I. This seems real small. Any one know if there is some secret metal my piston, jugs, or rings are made of to allow for such a small gap? Should I ignore the instructions and go with something like .018 or .020?

Any help would be great,

 

That seems awfully tight, considering the material used in those sleeves. My S&S 110" kit (with the "old" sleeve material) uses the same alloy as in your cylinders, and I recall that the clearance was something like .025" for the top and .030" for the second ring. S&S specified being careful to use their guidelines for clearance due to the particular liner material being used. I would check for sure before assembling your engine. Hopefully one of the engine builders on the forum will ring in with some sound advice for you.

 

Yup, cant find anyone who thinks that small of a gap is a good idea. On the other hand, there are a ton of these tire shredder kit out there and you would think that if it was a mistake someone would have said something by now/.

The worst case would be, I set the top gap at .016, which is their high end, and just go for it. Yet for the $2400 bucks I spent on the kit I hate to take that attitude.

 

I would take the time to check with Scott, Kirby and/or some of the other vendor/builders on the forum and see what they say. I would be absolutely positive you have enough clearance before you put it together and fire it. If you start it up and the ring ends butt together when it warms up, you're going to have instant scored cylinders. Not trying to scare you, just want to see you succeed.

 

Who makes the rings? What size are they and what material? Before I decided I knew more than the manufacture engineers. I would make sure I had all the info.

 

They are described as Screamin' Eagle high compression forged pistons. They are dark grey, feel rough except the top, and kind of light compared to the evo ones I installed years back. I will look on the bottom side of them to see who makes them. As for the rings they are just in some plastic sleeves that have them numbered 1,2,3. for the order they get placed.

 

Took me a second to find it but.....

 

yup, checked last night, thats the maker of my Pistons and I guess the rings, the ring package has no markings. Thanks for the info hrdtail78. I set them at .016 (Top end for harley and bottom for the manufacture) and now they just decorate my coffee table.

I wonder what Harley knows that the maker does not? What would be the worst thing that could happen if I set them at .018 = 4x.045, Thats what My harley mechanic brother says. I guess I would get some blow by, but would it be enough to affect performance or worse cause some damage over time?