Author Topic: engine number  (Read 315 times)

Offline Devlin

  • Moving Up
  • **
  • Join Date: May 2019
  • Posts: 9
  • Karma: 0
engine number
« on: 24.05. 2019 11:14 »
A7 engine number ZA&S S428  with HC stamped below
Frame                   ZA7S 6849
Can anyone decipher the actual model and engine type DVLA records it as a 1949 but nowt else
Devlin
Isle of Arran

Offline Swarfcut

  • Wise & Enlightened
  • *
  • Join Date: Oct 2018
  • Posts: 1274
  • Karma: 19
Re: engine number
« Reply #1 on: 24.05. 2019 11:57 »
Devlin  Frame ZA7S6849  should be a "spring frame" fitted with plunge rear suspension. This ZA7S series starts with ZA7S 101 in 1949, so by 1950 they were up to ZA7S 6001. By 1951, up to 14001. So, looks to be from early 1950.

 Engine number looks wrong, ZA7S would make it originally a Star Twin. Number 5428 puts it into 1950. Pictures of the numbers would help.

 BSA changed their model year at the Annual Summer Shutdown, so bikes actually made in the Autumn of that year were offered for sale as the New Model Year's Stock.

 Swarfy


Offline Devlin

  • Moving Up
  • **
  • Join Date: May 2019
  • Posts: 9
  • Karma: 0
Re: engine number
« Reply #2 on: 24.05. 2019 15:00 »
Ah well on its side is a step forward
Isle of Arran

Offline Swarfcut

  • Wise & Enlightened
  • *
  • Join Date: Oct 2018
  • Posts: 1274
  • Karma: 19
Re: engine number
« Reply #3 on: 24.05. 2019 16:27 »
Through the Patina, that number looks like ZA7S 428. It started life as a Star Twin, 1949. It is early in the production schedule, the Model Year started at ZA7S 101.  HC is a High Compression (for the time) variant.

 Cylinder barrel flange looks to be Longstroke Type, so I hope this to your liking and you have not bought a lemon.

 Picture has worked fine, give us a bit of a gallery. Just have another look at the frame number. Could be a later frame with an earlier engine. Have you any paperwork with this purchase?

 Get spraying with the WD while you decide your next move, and I reckon you will need a bit of heat on those nuts!

 Swarfy.

Offline Devlin

  • Moving Up
  • **
  • Join Date: May 2019
  • Posts: 9
  • Karma: 0
Re: engine number
« Reply #4 on: 24.05. 2019 16:39 »
Off down the workshop soon as the camera battery is charged as I get better results with the Olympus than the phone, WD40,wire brass brush,& beer, to hand,
Dev 
Isle of Arran

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8513
  • Karma: 112
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: engine number
« Reply #5 on: 24.05. 2019 20:36 »
G'day Devlin.
ZA7S 5428 motor would be a 1950 long stroke Star Twin. ZA7S 6849 frame same.
The short stroke A7's started in 1951 with engine number AA7 101 for the standard and AA7S 101 for the Star Twin.
My A7 is the 53rd AA7 off the line.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7