Piston Question

[JTR249]

What year did Indian make Chief or Sport Scout Lynite A pistons with the part number 85734?
What do the numbers on top of the piston mean?
I recently purchased two, NOS pistons with the above PN and on top of each were different numbers 3.2443 and 3.2427.
I would assume one is for front and the other for the rear?

-JR

[JTR249]

Here are a few photos.

[JTR249]

And the last two.

[PaulCDF]

JR

Found a little more (could not find our previous message)
In the AMCA Library there is: "Overhaul Instructions for Indian Four and illegible copies of Quick Shot Bulletins - 1928"

SPECIFICATIONS
Page 4
"Pistons - Cam ground Lynite pistons"
From this I am guessing Indian and Lynite/ALCOA had relationship dating from at least 1928 onward

I'm still hoping someone more knowledgeable will chime in with better answer.

[JTR249]

The listing said 1932-1940, I think. I'll keep check in the books also. I might have missed the number in the listings.
I did not know Lynite and Alcoa had a company involvement. Interesting.
Someone needs to offer an online course in Industrial Motorcycle Research.
Thanks, Paul.
-JR

[JTR249]

The 1944-1948 Parts List for Chiefs says the PN begins with 86. I noticed in earlier years Indian began piston PNs with 7. Going by this logic, the 85734 would be 43 or earlier, however the war era must have interrupted this. There should be a record in a list somewhere.
I'll keep looking.
-JR

[JTR249]

Found it!
1936-1937 pistons for a 74" motor.
See pages 18 and 20 of the Spare Parts List for the years 1936 to 1940.
-JR 1936 to 1940 Parts List p18.jpg1936 to 1940 Parts List p18.jpg1936 to 1940 Parts List p20.jpg

[PaulCDF]

Nice Work JR !!!!!

[Rubone]

Numbers on top appear to be actual diameter, one is approximately .020 oversize.

[JTR249]

Thanks, Rubone. I could not figure that one out.
-JR