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Piston question

PostPosted: Fri Dec 13, 2019 10:03 pm
by Bill
Hello,
I have a 1952 motor and noticed that on the piston has a #3 on it. Does the #3 indicate that this was rebuilt .030 over.
Thanks

Re: Piston question

PostPosted: Fri Dec 13, 2019 10:59 pm
by Mutt
They generally have 2 numbers like 3 and 20.

Re: Piston question

PostPosted: Sat Dec 14, 2019 12:47 pm
by Enaud90
How the piston is/was marked depends on who manufactured the piston. I have 55 NOS Harley pistons left on the shelf and a few Welworthy and Heplex (both English) pistons. A number 3 or 30 or .030 would indicate the piston is .030 oversize.
However, the 3 standard NOS Harley 125 cc pistons I have do not have a size marked on them. All the oversized ones are marked 5 , 10, 20, etc. The later NOS Harley pistons are marked .010, .020, etc. The reproduction pistons made
by Egge (USA) for J & M are very well marked and there is no question as to the size as it is very distinct.

Duane Taylor

Re: Piston question

PostPosted: Sat Dec 28, 2019 11:31 am
by Bill
Thank you both for the valuable information.