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A65 Stock Piston Weight #710872
10/08/17 1:30 pm
10/08/17 1:30 pm
Joined: Nov 2015
Posts: 10
USA
T
Thunderlizard Offline OP
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Thunderlizard  Offline OP
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Joined: Nov 2015
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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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Re: A65 Stock Piston Weight [Re: Thunderlizard] #710986
10/09/17 1:24 pm
10/09/17 1:24 pm
Joined: Apr 2005
Posts: 1,660
Mississauga, Ontario.
A
Adam M. Offline
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Adam M.  Offline
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Joined: Apr 2005
Posts: 1,660
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.
Re: A65 Stock Piston Weight [Re: Adam M.] #710987
10/09/17 1:29 pm
10/09/17 1:29 pm
Joined: Nov 2015
Posts: 10
USA
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Thunderlizard Offline OP
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Thunderlizard  Offline OP
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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

Re: A65 Stock Piston Weight [Re: Thunderlizard] #711020
10/09/17 6:34 pm
10/09/17 6:34 pm
Joined: Dec 2002
Posts: 3,257
arkansas
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leon bee Offline
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leon bee  Offline
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Posts: 3,257
arkansas
A lot of us out here would be glad to give you that info, but got no way to get an accurate weight.

Re: A65 Stock Piston Weight [Re: Thunderlizard] #711064
10/10/17 3:03 am
10/10/17 3:03 am
Joined: Aug 2001
Posts: 4,495
Owego, NY, USA
Mark Z Offline
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Mark Z  Offline
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Posts: 4,495
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.
Re: A65 Stock Piston Weight [Re: Thunderlizard] #711094
10/10/17 12:42 pm
10/10/17 12:42 pm
Joined: Apr 2005
Posts: 2,390
Bega NSW Australia
Mark Parker Offline
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Mark Parker  Offline
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Posts: 2,390
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
Re: A65 Stock Piston Weight [Re: Thunderlizard] #711169
10/11/17 12:10 am
10/11/17 12:10 am
Joined: Aug 2001
Posts: 4,495
Owego, NY, USA
Mark Z Offline
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Mark Z  Offline
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Joined: Aug 2001
Posts: 4,495
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.
Re: A65 Stock Piston Weight [Re: Thunderlizard] #711170
10/11/17 12:25 am
10/11/17 12:25 am
Joined: Aug 2001
Posts: 4,495
Owego, NY, USA
Mark Z Offline
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Mark Z  Offline
BritBike Forum member
Joined: Aug 2001
Posts: 4,495
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.
Re: A65 Stock Piston Weight [Re: Thunderlizard] #711175
10/11/17 1:28 am
10/11/17 1:28 am
Joined: Nov 2015
Posts: 10
USA
T
Thunderlizard Offline OP
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Thunderlizard  Offline OP
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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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