Brad has asked how I went about relocating the ring end pin in this piston, so I thought I would post it here so others may benefit.
First up, I'm no machinist, so others more knowledgeable in this area may have a more professional approach to this.
I have a drill press with a home made milling table attached, so made for a reasonably accurate lining up.
I removed the ring pin that protruded into the ring groove with a diamond impregnated bit after cutting level at the ring groove with a cut off disc in the Dremel. You can buy a packet of these diamond bits with various shapes and sizes for something like $10. (have seen them on Ebay etc) I ground out the pin with a cylindrical bit but left it flush with the back of the groove. I found the centre of the piston and mounted it in the vice. I used an end mill bit also known as a slot drill. Size is 1/16" which is 1.588mm in HSS 1/4" 6.3mm shank. The end mill bit is needed because your pin hole is half way off into the ring groove. I cut to the depth of the ring groove. From that point on, I used a 1.6mm drill bit. I made a pin out of a 1.7mm HSS drill bit for an interference fit. Now, when I used the end mill bit in my drill press, the drill chuck did run off centre a little so I ended up with the end mill bit cutting a fraction larger than the 1.6mm. This actually worked to my advantage as it didn't put any side pressure on the pin at the groove when inserting it. Cut your pin a tad shorter than your depth.
The reason I did this.
The 52mm kit piston is 35.3mm across the skirt. The Meteor 064 piston is 39mm across the skirt but is restricted by the ring ends to benefit from the increased width. When using the 064 piston in these 372BB's, you run them backwards as the ends are further apart on these against the Husky/kit piston and can foul with the upper transfers. So with the piston reversed you are restricted with the exhaust width due to the ring ends. By fitting a pin in the centre I run one ring at the top, the piston can be turned around to face the original correct direction and get the full potential of the skirt width.
With this kit I had the barrel milled .025 thou and ran the 064 piston as a popup. Because you gain revs by extra port area, I was wanting as much width/area as I could get without raising the roof so I could get good torque at high rpm for running larger bars. The trouble with this barrel is I had to raise the exhaust to 161° just to clean up the port and that's with .025 off the base, so I wasn't able to achieve exactly what I was chasing. Bummer. Anyway, it's turned out to be the most versatile 371/2BB yet for me so far.
