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#710872 - 10/08/17 1:30 pm A65 Stock Piston Weight  
Joined: Nov 2015
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Thunderlizard Offline
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Thunderlizard  Offline
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USA
Hello, new guy here with a question, I am building a 68 Thunderbolt from boxes of parts and it did not include the original pistons. I am trying to find out the weight of one original standard bore piston

thanks
Randy

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#710986 - 10/09/17 1:24 pm Re: A65 Stock Piston Weight [Re: Thunderlizard]  
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Adam M. Online content
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Adam M.  Online Content
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Mississauga, Ontario.
You don't need this information, Taiwanese JCC pistons sold on eBay are very good with weight and quality of workmanship.
They are also cheap for $100.- a pair. You just need good rings for them.

Last edited by Adam M.; 10/09/17 1:25 pm.
#710987 - 10/09/17 1:29 pm Re: A65 Stock Piston Weight [Re: Adam M.]  
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Thunderlizard Offline
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Thunderlizard  Offline
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USA
Thanks Adam, I already have a pair, I want to know the difference between the weight of them and the originals

#711020 - 10/09/17 6:34 pm Re: A65 Stock Piston Weight [Re: Thunderlizard]  
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leon bee Online content
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leon bee  Online Content
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arkansas
A lot of us out here would be glad to give you that info, but got no way to get an accurate weight.

#711064 - 10/10/17 3:03 am Re: A65 Stock Piston Weight [Re: Thunderlizard]  
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Mark Z Online content
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Mark Z  Online Content
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Owego, NY, USA
I have an original standard piston from a '67 Lightning. I will find it and weigh it, but too late tonight; will have to be tomorrow.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
#711094 - 10/10/17 12:42 pm Re: A65 Stock Piston Weight [Re: Thunderlizard]  
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Mark Parker Offline
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Mark Parker  Offline
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Bega NSW Australia
The std pistons are lighter than most, and early ones are different again. Sorry I don't have the weight of a std piston, but what looks like a + .020" JCC 397g a + .030" Hepolite 420g .040" 425g both latter style 9-1. MC 10-1 402g all with pins. Different brands can be different weights. Generally with cast pistons, the bigger the heavier because they are thicker in the skirt. Forged B44 80mm are around 372g with pin, 79.5mm Omega cast are about the same. T140 are 340g with pin.


mark
#711169 - 10/11/17 12:10 am Re: A65 Stock Piston Weight [Re: Thunderlizard]  
Joined: Aug 2001
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Mark Z Online content
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Mark Z  Online Content
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Owego, NY, USA
I didn't find the '67 L pistons, but I did find a pair of OE pistons from a '65 Lightning Rocket. I can't say for sure if they would have used the same pistons in '66, but it would seem likely. They appear to be 9:1 CR. I'll include the markings on the pistons if that helps anyone.

Piston 1: On the crown, 68-892 BSA/T, and 46/4/67 L. Next to the pin, 68-743 and AM, other side, LO-EX and L66. Weight without rings and gudgeon pin is 9.9 oz or 281 grams.

Piston 2: On the crown, 68-892 BSA/T, and 46/9/67 H. Next to the pin, 68-743 and AM, other side, LO-EX and M66. Weight without rings and gudgeon pin is 10.1 oz, or 286 grams.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
#711170 - 10/11/17 12:25 am Re: A65 Stock Piston Weight [Re: Thunderlizard]  
Joined: Aug 2001
Posts: 4,156
Mark Z Online content
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Mark Z  Online Content
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Owego, NY, USA
One other note: I had done this comparison a while ago, and left a note in the box. But that time I measured WITH rings and gudgeon pin.

Standard OE piston from '65 LR: 13.7 oz, or 389 grams.

EMGO Taiwanese +.040 piston: 15.1 oz, or 429 grams.

That's a pretty significant difference I would say...


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
#711175 - 10/11/17 1:28 am Re: A65 Stock Piston Weight [Re: Thunderlizard]  
Joined: Nov 2015
Posts: 3
Thunderlizard Offline
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Thunderlizard  Offline
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Posts: 3
USA
Wow, thanks everyone, that's a bunch to digest.

Randy

Last edited by Thunderlizard; 10/11/17 1:28 am.

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