Hi Bill, measure piston at the bottom of the skirt, in a front back direction. A standard cam ground Indian 45 piston will be around 0.008" thinner across the wrist pin direction. This pattern of piston was not introduced until the early/mid thirties, and allows for a tighter fit in the bore. Original 101 pistons ( if aluminum) were cylindrical, as piston technology had not developed far by 1928, and needed to be fitted with 0.008-0.010" clearance.

If you want to reuse the piston you will need to check the rings, and check that the ring lands are not worn. The rings in the cylinder should have an end gap of somewhere around 0.015-0.018 ".

New pistons are cheap enough, altho there may be a question mark over the rings that are provided with them.

Another option may be having the cylinder walls Nikasil coated, which will take them down by approx .040" , this seems like a good idea, and is a service that Vahan Dinanian on the west coast offers, altho I have no personal experience of doing this to an Indian cylinder. I would love to hear reports from anyone who has.

Keep us updated on how you go.

I aim for about 0.0045" on the front to back measurement with the cam ground pistons. The pistons usually come in at 0.003" under, ie for a standard bore of 2.875", the piston out of the box will measure 2.872", so to achieve the 0.0045" you would in this instance need to hone to 2.8765".