Author Topic: 3 7/16 pistons for 4 1/4 stroke  (Read 1273 times)

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Offline Lyle

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3 7/16 pistons for 4 1/4 stroke
« on: August 07, 2012, 04:48:00 PM »
I have done some serching and have found few options (s&s offers forged) for 3 7/16 dia pistons for 4 1/4 stroke. I am building a franken-knuck on a limited budget using some parts I have in my garage. Anyone have suggestions? Prefer cast but will run forged if no other options available. Keep in mind this motor is a rider, not a racer. Thanks!

Offline Lyle

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Re: 3 7/16 pistons for 4 1/4 stroke
« Reply #1 on: August 08, 2012, 07:56:54 AM »
My other options are: 1) bore my aftermarket 74" cylinders .060 and use stock 80" pistons. 2) Sell aftermarket 74" cylinders, bore cases, re-balance crank, and run 3 5/8 cylinders/pistons. I am using FHP/S&S heads so my options are open, just looking for opinions on all available options using parts on hand.

Offline Lyle

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Re: 3 7/16 pistons for 4 1/4 stroke
« Reply #2 on: August 10, 2012, 08:45:01 AM »
Well after many phone calls to machine shops and e-mails with S&S, boring 74" aftermarket cylinders is safe and reliable for a rider. So between now and spring ill have built a "budget", 80" Knuckle-Shovel. I cannot afford the 9K plus for the S&S version so building my own.

Base motor is 1979 80" Shovel
S&S cylinders and heads
Leineweber custom cam
OEM Knuckle tappet blocks
Aftermarket valve-train components

Ill start a new thread, post pics and put together a cost list for those interested as it progresses.