Hey guys,
So I have the new Wiseco pistons ready to install but there are no markings on the pistons for "front" (or anything else for that matter). Nothing in the instruction sheet either. I've been looking at the heads/valves but can't tell from that either. And nothing online from Wiseco that I could find.
Any ideas?

 

Part number/pad goes up.

 

Thanks Mark! You just verified the answer I got from Copper. And the bearing tangs up, away from oil pan, toward opposing piston. For a sec I thought maybe the pistons were put on backwards but I'm good to go.

 

Be sure to space the rings correctly too.

 

Ok, this brings up a question I have had questions about ring orientation for a long time. I have always used the instructions my Dad gave me to put the to top rings 180° apart and the oil control rings at 90° to them. I have only rebuilt a few engines and not had any issues with this but never researched it a great deal. I have also heard that piston rings rotate during operation but the marks I have found on them doesn't verify this. There are several very good engine builders on this forum, what say you? Is there a specific piston ring orientation that you use, and why? All opinions welcomed if you have a reason for it.

 

The three piece oil ring need the gaps separated. The others will not matter but out of habit I separate them. The rings will rotate in the bore but I have seen old worn out engines where the rings have to much gunk in them and no longer move.

I use to build 100's of ATV engines and one time we were testing some different pistons. We had the same engine apart several times. on one piston I lined the top two ring gaps up to show my buddy they move. We ran it about 4 hours and took it apart to put in another piston. Both ring gaps were in complete different places.

 

I clocked the rings according to the piston recommendations. I don't remember the specifics. I know that Bill Trovato says not to worry about it but I thought, what the heck, it won't hurt anything and wasn't difficult.
As far as the rings rotating during operation, I would suspect that once the cylinders are even just a little out-of-round, they won't rotate. Fingers crossed that doesn't happen with the gaps all lined up! Lol.