Author Topic: What is it?  (Read 577 times)

Offline worntorn

  • Valued Contributor
  • ****
  • Join Date: Jun 2015
  • Posts: 376
  • Karma: 2
What is it?
« on: 20.09. 2017 11:21 »
Engine number seems to indicate 1956 swing arm Gold Flash, but why the HC below?
Would the frame be from 1961?

Offline Topdad

  • bob hebdon
  • Wise & Enlightened
  • *
  • Join Date: May 2011
  • Posts: 2235
  • Karma: 32
  • l
Re: What is it?
« Reply #1 on: 20.09. 2017 12:14 »
Doesn't CA indicate small journal and HC ,high compression with sport cam , I'll await being told what they really stand for.
" rules are made for the guidance of wise men and the blind obediance of fools"
United Kingdom

Offline BritTwit

  • A's Best Friend
  • ***
  • Join Date: Apr 2017
  • Posts: 90
  • Karma: 0
Re: What is it?
« Reply #2 on: 20.09. 2017 13:08 »
My understanding of the designation is as follows:

HC      High Compression
HHC    High Lift Cam + High Compression 

Online bikerbob

  • Resident Legend
  • *****
  • Join Date: Feb 2011
  • Posts: 536
  • Karma: 7
Re: What is it?
« Reply #3 on: 20.09. 2017 15:15 »
That frame number would indicate that it is a 1954 either A7 or A10 swinging arm frame. 1954 began CA7 -101 whilst 1955 began CA7 7001

Online chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3212
  • Karma: 46
Re: What is it?
« Reply #4 on: 20.09. 2017 16:12 »
1961 Super Rocket
1963 RGS (ongoing)

Offline worntorn

  • Valued Contributor
  • ****
  • Join Date: Jun 2015
  • Posts: 376
  • Karma: 2
Re: What is it?
« Reply #5 on: 21.09. 2017 22:07 »
I'm thinking now that it would be a 1955 frame since 54 and 55 were the only years for a CA7 prefix and this is 13,356, very near changeover to the next frame prefix, FA7. BSA started the CA7 frames at 101in 1954 and were at 7001 by the  a beginning of 55, so 7000 frames per year puts 13,356 as a very late 55.
It appears  new models start at engine and frame 101 as a rule .
The engine appears to be a 1956 Gold Flash, but why would a Gold Flash be designated HC  or high compression? Wasn't high compression limited to the sports models, the RR and SR etc ?
Did the 56 swing arm Gold Flash have an alloy head?
This engine has an alloy head, but it might not be original

Glen

Offline trevinoz

  • Newcastle, N.S.W. Australia.
  • Wise & Enlightened
  • *
  • Join Date: Jul 2006
  • Posts: 2888
  • Karma: 67
Re: What is it?
« Reply #6 on: 21.09. 2017 22:21 »
Glen. '56 & '57 frames were EA7.
Regarding the "HC", remember that the standard compression ratio was 6.5:1 and if higher compression pistons were fitted, I think usually 7.25:1, the case was stamped "HC".
It is not uncommon on Flash cases, I have a set of BA7 cases so stamped and have seen others.

Online chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3212
  • Karma: 46
Re: What is it?
« Reply #7 on: 21.09. 2017 22:28 »
Hi Glen,
Does the engine fitted have a thick flange cylinder?
It is not unusual after all the years for engines to be rebuilt using cases cylinders and heads etc from different years
and models
It would be interesting to know whats inside the engine now? big or small journal crank, cam type etc
A boroscope inspection would show what pistons are fitted

John
1961 Super Rocket
1963 RGS (ongoing)

Offline Clive54bsa

  • A's Best Friend
  • ***
  • Join Date: May 2012
  • Posts: 128
  • Karma: 1
  • Orange SoCal
Re: What is it?
« Reply #8 on: 21.09. 2017 22:31 »
They made Road Rockets in '54


'54 GF,  '61 SR,  '71 B50MX

Offline JulianS

  • 1962 A10
  • Resident Legend
  • *****
  • Join Date: Mar 2017
  • Posts: 987
  • Karma: 20
Re: What is it?
« Reply #9 on: 21.09. 2017 22:50 »
The engine was probably made for the export market and fitted with higher comp pistons to suit that market.

The first Road Rockets came out in April 1954 and was export only until 1956 season. The bulk went to either Hap Alzina on West Coast USA or Rich Childs later BSA Incorporated on East Coast.

The thick flange barrels arrived in 1957 on the Road Rocket.

Online RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5032
  • Karma: 48
Re: What is it?
« Reply #10 on: 22.09. 2017 00:24 »
Jeez, Julian, were you at the Small Heath auction where they sold the file cabinets?

Richar 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 worntorn

  • Valued Contributor
  • ****
  • Join Date: Jun 2015
  • Posts: 376
  • Karma: 2
Re: What is it?
« Reply #11 on: 23.09. 2017 02:57 »
The engine has thin flange cylinders.
Thanks for the replies, now I know it is a 56 
Gold Flash engine, high compression ( but not very high) and a 55 twin frame.
My friend is hoping to buy this bike and asked if I would post the question.

Glen

Btw,  wouldn't the engine above , CA10  755
be a 54 Gold Flash ? I believe the Road Rocket would be CA10R.

Offline JulianS

  • 1962 A10
  • Resident Legend
  • *****
  • Join Date: Mar 2017
  • Posts: 987
  • Karma: 20
Re: What is it?
« Reply #12 on: 23.09. 2017 09:07 »
Agree CA10 755 is a Golden Flash motor, probably exported given the HC.

Road Rockets are found with prefix CA10R and CA10RR.

Offline BritTwit

  • A's Best Friend
  • ***
  • Join Date: Apr 2017
  • Posts: 90
  • Karma: 0
Re: What is it?
« Reply #13 on: 23.09. 2017 15:42 »
Agree CA10 755 is a Golden Flash motor, probably exported given the HC.

Road Rockets are found with prefix CA10R and CA10RR.

I've had both.  Never figured out what the extra "R" meant.