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Re: BSA A70 Lightning parts vs A65 [Re: Morgan aka Admin] #766828 03/01/19 12:13 pm
Joined: Aug 2014
Posts: 339
Keane Lucas Offline
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Morgan,
I have NOS A70 BSA/Hepolite pistons.
At this time,I can offer,one pair, of one of, the following-
STD. - 71-2710 stamped 71/2666
+.020- 71-2884 stamped 71.2667
+.040- 71-2885 stamped 71.2668
Yes, slashes and dots.
These pistons include rings,gudgeon pins,and circlips.
For less than 1/2 the ED V piston price.+ shipping.

At factory timing specs,
my 9.5:1 engine is not happy with R+M/2 93 octane -97ron fuel.
It is happy with R+M/2 96 octane -100ron fuel.
Others here seem to have better luck,with lower grade fuels.
Send me a pm,if interested.


1969 BSA A65T w/A70 engine
1970 Royal Enfield Interceptor S ll
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Re: BSA A70 Lightning parts vs A65 [Re: Morgan aka Admin] #766831 03/01/19 12:24 pm
Joined: Jul 2001
Posts: 2,191
Morgan aka Admin Offline OP
Ride safe today!
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Keane, can you please hold all those pistons for me for a while, I need to sort things out for with this A70 purchase. I will PM you


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Morgan Johansson
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Re: BSA A70 Lightning parts vs A65 [Re: Morgan aka Admin] #767011 03/03/19 2:40 pm
Joined: Jun 2013
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Ray Elliott Offline
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Keane Lucas has shared some A70 piston pictures with me. They have been uploaded to my folder.

Thank you Keane!


Ray Elliott
---
A65, A70, A75, T120, T140, T150, T160
Re: BSA A70 Lightning parts vs A65 [Re: Ray Elliott] #767012 03/03/19 3:07 pm
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Morgan aka Admin Offline OP
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Originally Posted by Ray Elliott
Keane Lucas has shared some A70 piston pictures with me. They have been uploaded to my folder.

Thank you Keane!

Got the 6 photos thank you, the weight of the pistons are that in gram? 71/2666 = 395,2 gram ?


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Re: BSA A70 Lightning parts vs A65 [Re: Morgan aka Admin] #768080 03/14/19 8:20 am
Joined: Apr 2005
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Mark Parker Online Content
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I read once that people at BSA were quite excited about the development potential of the A70. And it's possibly because of what was found out about the A65s in 1970 when Umbeslade Hall technicians built an engine for the photo shoot '71 model Firebird. They ported the twin carb head's inlet ports to the design drawing, not something the factory had ever done. The result was a much more responsive, better accelerating motorcycle, with around 8HP gain on their dyno over production line engines. The std production twin carb head flows around 109cfm @ 28"W giving around 50hp at the crank, to get 58hp would require 123cfm, equivalent to the best stock Commando head. On the 650 it would mean the engine would make power to 8,000 or so. On an A70 power to 7,100rpm, and there would be a lot of it right through the range. Probably faster than a 3 because it's lighter. Plus there is development potential on top of that especially with the strengthened crankshaft. 142cfm through a properly machined head could give power to 8,000 and around 65-67hp with a relatively small port, which would give a very healthy midrange. And this would be a mildly tuned engine; 9-1 comp and stock Spitfire cam.


I think what they built with the A70 was simply what they needed to homologate the flat track 750, had BSA not run out of money I think the A70 in following years would have realized much more of it's potential.


mark
Re: BSA A70 Lightning parts vs A65 [Re: Morgan aka Admin] #768356 03/17/19 5:49 pm
Joined: Aug 2014
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Keane Lucas Offline
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Originally Posted by Morgan aka Admin
Originally Posted by Ray Elliott
Keane Lucas has shared some A70 piston pictures with me. They have been uploaded to my folder.

Thank you Keane!

Got the 6 photos thank you, the weight of the pistons are that in gram? 71/2666 = 395,2 gram ?

Yes grams,here,this weight includes rings,gudgeon pins.
Did not want to take them apart.
The pair of circlips are another 1g.
Thank you Ray
I apologize for the delayed reply.


1969 BSA A65T w/A70 engine
1970 Royal Enfield Interceptor S ll
Re: BSA A70 Lightning parts vs A65 [Re: Morgan aka Admin] #780197 07/31/19 6:21 pm
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Posts: 2,191
Morgan aka Admin Offline OP
Ride safe today!
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Oh I treated me good today.. it became an A70.. one of the few..
here it is..

Its one of the early built in June 1971 with original paint on the frame, Don't know of another grey frame for the A70.
Let me know what you think!

Attached Files
bsa_a70_on_trailer.JPG (84.08 KB, 92 downloads)
BSA A70 1972
Last edited by Morgan aka Admin; 07/31/19 6:22 pm.

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Re: BSA A70 Lightning parts vs A65 [Re: Morgan aka Admin] #780201 07/31/19 7:27 pm
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Allan Gill Offline
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Looks good Morgan, I didnt think there was any dove grey A70’s. Sure does look shiny though!


beerchug
Re: BSA A70 Lightning parts vs A65 [Re: Morgan aka Admin] #780208 07/31/19 8:22 pm
Joined: Jul 2001
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Morgan aka Admin Offline OP
Ride safe today!
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Had a good long test ride today and it runs different to my A65 for sure with that long stroke. I'll be back to discuss A70 parts soon.
Allan on above photo its not tidy at all we rode a long test ride on twisty rainy roads so its pretty dirty. I will spend time cleaning it tomorrow and take photos for the insurance and maybe some to post here and there..

Last edited by Morgan aka Admin; 07/31/19 8:25 pm.

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Morgan Johansson
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Re: BSA A70 Lightning parts vs A65 [Re: Morgan aka Admin] #780265 08/01/19 2:38 pm
Joined: Aug 2006
Posts: 1,395
No Name Man Offline
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Congratulations on your acquisition Morgan...and I am jealous.


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