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Confuse. My B31 with weird engine number #376986
06/03/11 3:32 pm
06/03/11 3:32 pm
Joined: Jun 2011
Posts: 8
Indonesia
C
cesariaputeri Offline OP
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cesariaputeri  Offline OP
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Joined: Jun 2011
Posts: 8
Indonesia
Hello,

Anyone can help me? I have a BSA, i bought it 3 months ago. The seller said it is B31 1956, and its look like B31 and i love this bike (my first brit bike).



But on engine number write CB32 GS 635 and the frame number EB31 3383. At other side the engine, near the top of timing alloy cover, very small number wrote 51 56.
Is it true engine number for B31 1956? Anyone help me please. I'm very confuse.

Thank You.
Cesaria Puteri

Last edited by cesariaputeri; 06/03/11 3:33 pm.
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Re: Confuse. My B31 with weird engine number [Re: cesariaputeri] #376991
06/03/11 3:48 pm
06/03/11 3:48 pm
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

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Alex  Offline

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Posts: 7,813
Seattle
Cesaria,

CB32 GS indicates the crankcase is a gold star 350 case from 1954. Originally, this would have come with an alloy barrel and piston, though and iron top end will fit right on. It's possible that the original cases were damaged beyond repair and the Gold Star cases were the best ones available at the time for repair. It would not have been original to the frame. Your frame is correct for the '56 model year, though.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
Re: Confuse. My B31 with weird engine number [Re: Alex] #376996
06/03/11 4:36 pm
06/03/11 4:36 pm
Joined: Jun 2011
Posts: 8
Indonesia
C
cesariaputeri Offline OP
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cesariaputeri  Offline OP
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Joined: Jun 2011
Posts: 8
Indonesia
Thank You Alex.
Is there any difference between goldstar 350 crankcase and B31 350 crankcase?
Is there any difference between goldstar frame and B31 frame?
Can you tell me the meaning of number 51 56 at the other side of the bike?
Sorry for asking too much.

Thank You.
Cesaria

Re: Confuse. My B31 with weird engine number [Re: cesariaputeri] #377004
06/03/11 5:09 pm
06/03/11 5:09 pm
Joined: Oct 2008
Posts: 1,681
Canada
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LarryLebel Offline
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Canada
I'm guessing 5156 is a casting number.

Re: Confuse. My B31 with weird engine number [Re: cesariaputeri] #377015
06/03/11 5:57 pm
06/03/11 5:57 pm
Joined: Apr 2002
Posts: 962
North East England
beezageezauk Offline
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beezageezauk  Offline
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Posts: 962
North East England
Cesaria,

Is the small number 5 1 56 and is it stamped upside down?

If it is then I was told that this is normally the date that the engine was originally built up at the factory. In this instance 5th. January 1956. If so, it doesn't tally with the following paragraph and maybe somebody can throw some more light on this subject!!

Further to Alex's comments. My information shows that the CB32GS started in 1954 with number 101 and for 1955 from number 501. You then have a 1955 engine.

Everything else looks correct for 1956.

Beezageezauk.



Beezageezauk.


Last edited by beezageezauk; 06/03/11 5:59 pm.
Re: Confuse. My B31 with weird engine number [Re: beezageezauk] #377026
06/03/11 6:52 pm
06/03/11 6:52 pm
Joined: Jun 2011
Posts: 8
Indonesia
C
cesariaputeri Offline OP
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cesariaputeri  Offline OP
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Joined: Jun 2011
Posts: 8
Indonesia
Beezageezauk,

You are right, the small number stamped upside down on the cb32gs crankcase. So what do you think, is this "1955 engine" that was build on 5th January 1956? Does "B31 1956" use cb32gs's crankcase? Because my information shows, In 1956 Goldstar use engine number DB32GS 501.

By the way i live in Pematangsiantar, Indonesia. In my city there are 700 BSA use for paddy cab.

Thank You,
Cesaria

Re: Confuse. My B31 with weird engine number [Re: cesariaputeri] #377055
06/03/11 9:07 pm
06/03/11 9:07 pm
Joined: Apr 2002
Posts: 962
North East England
beezageezauk Offline
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beezageezauk  Offline
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Joined: Apr 2002
Posts: 962
North East England
Hi again Cesaria,

I reckon that your B31 did not leave the factory with the CB32GS engine in it. The bottom half of the engine you have is from a 1955 350cc Goldstar. What's more, I think it's much more rare than the B31 engine and therefore more valuable.

Unfortunately, I can't explain how the CB32GS cases have the date stamp for a year after the engine was made. One of BSA's little mysteries eh!!

I've seen pictures of the single cylinder BSA paddy cabs in Indonesia and I really appreciate how you guys keep them running as a business. I was told that hundreds of them meet up together each year. The picture I saw was taken at one of those events.

I guess the owners are very knowlegable and skilful in maintaining them. They have my total admiration.

Don't worry too much about numbers. Ride the bike and enjoy it for what it is. That's what is was made for.

Beezageezauk.

Re: Confuse. My B31 with weird engine number [Re: cesariaputeri] #377137
06/04/11 11:23 am
06/04/11 11:23 am
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

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Alex  Offline

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Joined: Sep 2002
Posts: 7,813
Seattle
Is it possible that only the timing side of the case was replaced? That would make sense in this case (no pun intended)


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
Re: Confuse. My B31 with weird engine number [Re: Alex] #377156
06/04/11 2:11 pm
06/04/11 2:11 pm
Joined: Apr 2002
Posts: 962
North East England
beezageezauk Offline
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beezageezauk  Offline
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Joined: Apr 2002
Posts: 962
North East England
Good thinking Alex. I think you are spot on there. Now why didn't I think of that??

The crankcase matchmarks are behind the front engine plates on the s/a B31 so it would be a relatively easy thing to check.

Cesaria...the crankcases had identical numbers stamped on each half when the engine was built. Normally a three figure number, it was stamped on the front of the cases and in the same position for both sides.

Beezageezauk.

Re: Confuse. My B31 with weird engine number [Re: cesariaputeri] #378456
06/12/11 8:45 am
06/12/11 8:45 am
Joined: Jun 2011
Posts: 8
Indonesia
C
cesariaputeri Offline OP
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cesariaputeri  Offline OP
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Indonesia
Beezageezauk,

I look on the front of crankcases , there are two row number. The first number is 66 1641 and the second number is 187 187 on both side of crankcases. Can you tell the meaning of that number please.

Thank You
Gata Simaringga

Last edited by cesariaputeri; 06/12/11 8:48 am.
Re: Confuse. My B31 with weird engine number [Re: cesariaputeri] #378474
06/12/11 11:29 am
06/12/11 11:29 am
Joined: Apr 2002
Posts: 962
North East England
beezageezauk Offline
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beezageezauk  Offline
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Joined: Apr 2002
Posts: 962
North East England
Ok Gata,

66-1641 is the casting number for the crankcase half, this is one number different from the actual part number of 66-1642. The 187 on both sides of the crankcases show that they were a matching pair when the engine was originally built.

So that throws out our theory that the left half with an earlier engine number was a replacement part.

Back to square one. Has anybody else got any ideas??

It it possible that the GS crankcases were on the shelf at the factory a year after they were made and used for this particular bike?? Personally I doubt it but it is possible!!

Beezageezauk.

Beezageezauk.


Last edited by beezageezauk; 06/12/11 11:37 am.
Re: Confuse. My B31 with weird engine number [Re: beezageezauk] #378488
06/12/11 12:52 pm
06/12/11 12:52 pm
Joined: Jun 2011
Posts: 8
Indonesia
C
cesariaputeri Offline OP
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cesariaputeri  Offline OP
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C
Joined: Jun 2011
Posts: 8
Indonesia
Beezageezauk,

Beezageezauk, thank you for many information from you.
Is there any different between BB31's crankcase and GS's crankcase?

Many BSA used for Paddy Cab in our city (City Pematangsiantar, Country Indonesia).














Gata Simaringga

Re: Confuse. My B31 with weird engine number [Re: cesariaputeri] #378503
06/12/11 3:17 pm
06/12/11 3:17 pm
Joined: Apr 2002
Posts: 962
North East England
beezageezauk Offline
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beezageezauk  Offline
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Joined: Apr 2002
Posts: 962
North East England
Gata,

I'm not too familiar with Goldstar engines but I'm pretty sure that the CB32GS engine will have a thick flange where the crankcases bolt together and the B31 engine will have a thin flange. Check where the matching numbers are (187 187) and see if both flanges are the same thickness. If they are both the same tell me the measurement across both flanges.

This should tell you if the crankcases were matched when new and if they are genuine GS cases or not.

Beezageezauk.

Last edited by beezageezauk; 06/12/11 3:18 pm.
Re: Confuse. My B31 with weird engine number [Re: beezageezauk] #378629
06/13/11 9:16 am
06/13/11 9:16 am
Joined: May 2011
Posts: 134
Muriwai,New Zealand
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Llewelyn Offline
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Llewelyn  Offline
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Joined: May 2011
Posts: 134
Muriwai,New Zealand
Originally Posted By: beezageezauk
Gata,

I'm not too familiar with Goldstar engines but I'm pretty sure that the CB32GS engine will have a thick flange where the crankcases bolt together and the B31 engine will have a thin flange. Check where the matching numbers are (187 187) and see if both flanges are the same thickness. If they are both the same tell me the measurement across both flanges.

This should tell you if the crankcases were matched when new and if they are genuine GS cases or not.

Beezageezauk.

Early xb motors have thin crankcase flanges but zb's and later are thickened up


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