Author Topic: Con rod length  (Read 358 times)

Online muskrat

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Con rod length
« on: 14.09. 2016 10:18 »
Mention was made of short rods in an A10 in Richard A's topic http://www.a7a10.net/forum/index.php?topic=11051.0;topicseen.
Not wanting to get away from his original post I thought I'd start this one.
Rocker Racer has put 6" rods in his racing A10 outfit shortening his barrels by 1/2".
I went the other way with my racing A7SS. I used A75 pistons that had a shorter crown height so needed longer rods. I shortened A10 rods by 2.5mm to give me a 14:1 comp ratio to run on methanol.
Just wondering if any other members have tried any other combinations. Briz, Danmar, Dan ???
Found this article and thought it interesting reading. http://victorylibrary.com/mopar/rod-tech-c.htm
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline Rocket Racer

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Re: Con rod length
« Reply #1 on: 14.09. 2016 22:34 »
http://victorylibrary.com/brit/A10-c.htm

Aplogies the attachment is poor quality have misplaced the original
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Online RichardL

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Re: Con rod length
« Reply #2 on: 14.09. 2016 23:04 »
RR,

Thanks for posting the article. I think it would be a great read if it was readable. If you have a scanner you could make a pdf Then, if you are familiar with the technique, you could put it on GoogleDrive and give us the link. If too much trouble, still thanks.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline Rocket Racer

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Re: Con rod length
« Reply #3 on: 14.09. 2016 23:28 »
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Online RichardL

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Re: Con rod length
« Reply #4 on: 15.09. 2016 01:32 »
Read it. Love it. Can't do it.

As a side note, being from California, all the places named are familiar. I have a feeling I won't be able to stop in at Hap Alzina's, which is where my own bike shipped to in '55.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline Rocket Racer

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Re: Con rod length
« Reply #5 on: 15.09. 2016 02:37 »
Those places sound so exotic...   We have the "American" factor to thank for driving BSA to develop the sports twin models. Particularly the American love of flat tracking.
My favourites being the factory daytona racers of '54
the barrel you get if you follow the instructions  *dribble*
also featured in http://www.a7a10.net/forum/index.php?topic=1998.90
(bottom of page 7)
Short rod motors also improve ease of fitting rocker boxes as the top end is 1/2" lower than a stock motor, also improved space around the carb's.
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Online RichardL

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Re: Con rod length
« Reply #6 on: 15.09. 2016 14:34 »
RR,

Like I said, I can't do it, as I lack the machinery and, maybe, courage. I am, however, curious about one detail from the article and how you did it. They say to build up a welded lip at the back edge of the pushrod tunnel. I assume this is because the pointy part recedes as material is removed. Is yours built up? I can't tell.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.