Does anyone know if the wrist pin is supposed to fit in the con rod?
tight but free to rotate?

I got one that took some effort to get out.
A new pin won't go in w/o a persuader.

Does the wrist pin fit correctly in the piston?


If so, lightly tap it into place and go on with life.   The fit is supposed to be a snug one and somebody's tolerance slipped a bit (or else if it is Wisco replacement pin they are attempting to go print max to take up for rod end wear in in the typical engine their stuff goes into (an older engine).

If you have to beat it into place, that is too much.   Lightly tap in place isn't bad as that is considered "correct fit" in some engines.   Make sure it is evenly spaced on both sides (does not load the ring clips).  

It should be able to drift side to side slowly over time as the engine seats itself in .....

Those with loose wrist pin to small con rod end with snug to piston fits do all the rocking at the small end of the con rod.   This is a bad idea using hardened steel on steel, most of these type set ups have a needle bearing on the wrist pin/con rod.

Those with snug fits to con rods and loose fits to piston do most of the rocking at the piston (steel pin in aluminum).

Some bike engines allow both, until the steel on steel at the con rod eventually varnishes up or galls up tight anyway -- then the rocking all takes place steel on aluminum at the piston.

I can't speak for all Savage engines, but the ones I have been into allowed rotation (with some resistance) at the steel on steel con rod junction.  It was a tight fit but it could rotate.   I suspect most of the rocking action still takes place at the pin/piston joints as the area loading is a lot less and they are dissimilar metals with an oil film to keep them from galling.

I always clean the varnish off the pin and the inside of the con rod.  Perhaps you have a bit of varnish build up inside the con rod?  Mebbe a little galling too?

Thanks for the input.
Looking at the pin in the wiseco piston, the wear pattern indicates that it rotates in the piston most.
I polished out the bad spot in the con rod and tapped the pin into place.

Boofer wrote on 07/10/11 at 09:52:27:


I just checked my old stock piston and wrist pin,  With the retaining clips in place, the wrist pin will move end to end about 1/16 inch.

FYI, here's what the wear pattern looks like on my stock wrist pin:

I don't know how Harley pistons are designed, but as you can see with the stock LS650 piston, the wrist pin is recessed into its hole, and the ends of the holes are recessed from the diameter of the piston. The retaining ring would need to come out before the wrist pin could touch the cylinder. I suspect HD pistons are similar.



As you can see, the Wiseco piston used for LS650 big bores is even narrower at the wrist pin.

I appreciate the comments on how it should be, but sometimes things don't work right. That is why most people come on here asking for help. I took my car to a guy who told me his wife's car never had the problems mine had, so I'm thinking, "Okay, I'll go to someone with an open mind to look for all the probablilities and then run through the impossibilities." BTW I have a friend who is running a small block Chevrolet I put together ten years ago. Bored .030, .010-.010 on the crank, recon rods, torker intake, Holley carb, Manley springs, Racer's Warehouse push rods, etc. When I was around 21 I took my brother's Kawa 90 jug off and found needle bearings on top of the piston. Bought rings, wrist pin and a little creative sanding by hand. But no, that couldn't happen.

remember the piston and con rod are both aluminum and the wrist pin is steel Coefficient of expansion for AL is 3 x what it is for steel so the assembly should not be more than a light thumb press fit tight and they will open up as the engine warms ups and will generate the correct funning oil clearance.