The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: olev on 22.05. 2009 14:09

Title: Engine numbers
Post by: olev on 22.05. 2009 14:09
As part of an engine rebuild, the cases on my 52 star twin need to be replaced as sometime in the past they've had major repairs and are warped.
While it would be good to obtain the correct cases for the year, in the last 6 months I haven't been able to find any decent A7 plunger cases, let alone a set for a star twin.
Cases off an A10 are available but the engine number would then imply its a 650 rather than a 500.
Originality is not a big issue but thats a bit too ordinary.
Does anyone have thoughts on legal or moral issues in restamping a set of A10 cases with my original engine number?
I wouldn't be able to sleep at night if I did the wrong thing.
Title: Re: Engine numbers
Post by: LJ. on 22.05. 2009 17:33
I dont think the earliest A10 cases are anything like the A7 cases as the timing cover side has a much flatter top. I stand to be corrected though probably Brian will tell as he has both bikes. But as far as restamping the number... It's never the same is it? You'd have to grind off the old one and probably quite deeply and then applying the new one stamped over the gash. It'll always show and the stamps may not be the same as the genuine old ones. Maybe I'm too picky?

Might be worth getting in touch with this guy, read his questions and answers.|65%3A13|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A50

Good Luck!
Title: Re: Engine numbers
Post by: A10Boy on 22.05. 2009 21:13
Aside from the technicalities of A7 - A10 cases, there is an interesting story regarding a BSA which was destroyed in the fire at the national Motorcycle museum, and goes to highlight the seriousness of altering numbers.

As with most of the bikes which were burnt, they didn't just go out and buy replacements, they restored and rebuilt most of the bikes if there was anything left, even re-brazing frames back together in order to keep the original numbers in place.

There was one BSA, I think it was an A7, which was severely damaged, most of the alloy parts had disappeared and the crank cases had all but gone, apart from the area where the Engine Number was stamped.

The museum approached the BSAOC and asked them if they could use another pair of cases, weld over the numbers and stamp the engine numbers from the burnt bike in their place. The BSAOC refused permission outright, so the museum cut out the engine number from the "old" burnt cases and welded that section into the replacement cases. This was acceptable to the BSAOC as the original number hadn't been tampered with in any way.

This in the light of a massive amount of sympathy towards the Museum, but no way were they going to let them alter a number, there are serious legal issues if anyone does.
Title: Re: Engine numbers
Post by: olev on 23.05. 2009 00:34
Thanks for the comments,
The bike in the ebay ad is the early A7.
I'm pretty sure the cases of the A10 and A7 are the same from about 1951 up to the end of plunger production - 1956?
The quality of the stamping isn't a problem. I hear a local villian does an excellent job.

I've been tempted by the cases below but the US$135.00 postage makes it expensive if they are scrap.

Do you think I'd get more sympathy than the museum?

Title: Re: Engine numbers
Post by: Brian on 23.05. 2009 04:09
According to the parts book the cases from 51' up are the same for the A7 and A10. It might take a bit of searching but you should be able to find a set of replacement cases if necessary.

How bad are your original cases. Most things can be repaired with a decent engineer doing the work.

As to restamping I guess if its your bike you can do as you please but I wouldnt do it. Being a Star Twin I would salvage the original cases with the original number if at all possible. Failing that buy a set of cases and use to get the bike up and running all the time watching out for a replacement set.

If oneday in the future you sold the bike you could explain to the purchaser that the original cases where damaged and the ones in the bike are replacements and give them the original cases with the bike. I am sure a prospective buyer would be happier with that than at a later date find out the numbers had been restamped.

Remember that numbers are just that, numbers. They have nothing to do with how the bike goes or looks etc. I am sure that if you where at a show or similar and you explain that you had to fit replacement cases due to the originals being damaged no-one would think less of you or your bike because of it.

Its nice to have original numbers and things when possible but its a lot nicer to have a bike to ride. Riding them is a lot more fun than just looking at them. Do what you have to do to get the bike going but keep looking for the correct parts and if they turn up then good. If not then you still have a nice bike to ride.

Title: Re: Engine numbers
Post by: olev on 23.05. 2009 10:48
My drive side case had been repaired after a rod apparently escaped through it.
Sometime after the crankcase was repaired the motor managed to chew a hunk out of the timing side bearing and seize both pistons solid.
Now when the cases are fitted together there is a 10mm gap at the top front. The gap can be closed by tightening up the crank case bolts. The thing is severley sprung.
I suspect a magician couldn't fix it but would love to hear otherwise.
Its interesting, you can have a machine like grand dads prized original axe (only had 2 new heads and 6 new handles) and every one is happy providing you keep modifying it around the 2 square inches containing the frame and engine numbers.
Actually its not interesting its bullsh*t.
Did BSA sell crank cases as spares?
A few years ago you could buy a set of blank Volkswagen cases made in Brazil. When your beetle detonated, the engine was rebuilt and the old numbers stamped back in.
Looking at a standard BSA twin bottom end the factory should have done a roaring trade in drive side crankcase halves.
This bike will be rebuilt with electronic ignition, oil filter, 12 volt electrics, srm oil pump and a japanese carburettor. Do you think its worth the trouble and expense to make the base motor original?
hoping for a response,
Title: Re: Engine numbers
Post by: Brian on 23.05. 2009 11:24
Like I said, numbers are just numbers.

BSA certainly did sell crankcases as spares and not in pairs. They did recommend that you send the other half to them for machining if you wanted only one half.

I would get a set of replacement cases and use them and if a set of Star Twin ones come along one day then good, if not, so what.

Get the bike on the road and ride it.

Title: Re: Engine numbers
Post by: olev on 23.05. 2009 11:40
I intend to get the thing on the road.
Whether its worth riding, I'll be the judge of that.
If BSA recommended you use the same engine number on their replacement case (as volkswagen) the museum have gone to a lot of wasted effort.
I personally can't see the difference between stamping a new set of cases or re-stamping an old set if you have that precious square inch of alloy??
Title: Re: Engine numbers
Post by: Brian on 23.05. 2009 12:13
Its possible that the BSAOC took such a strong stance on the engine numbers of the A7 in question due to the particular bike in question. Now I dont know for sure but I think it may have been the Maudes Trophy bike. This particular bike has quite a lot of history and they may not have been too keen to see it restored unless it was original.

However if they cut the old engine number out of the cases and welded that piece into another set then that was ridiculous.

This whole discussion opens up endless ways of looking at the whole originality argument. If you cant replace the cases because it destroys originality what happens if you put new pistons in, or a new set of barrels etc etc. How often do you read in the classic magazines that someone has built a totally original bike from spares. Its an endless arguement.

Your bike will definitely be worth riding, the plunger A7's are great bikes.
Title: Re: Engine numbers
Post by: olev on 23.05. 2009 14:18
Actually I've got to confess, this thread wasn't started while I was in the best of moods.
I'd been doing some serious negotiating with the gentleman in Ballarat who reputedly has 7 tons of BSA parts in the ceiling of his house. He claimed to have a set of AA7S cases for which he wanted $400.
I had been quoted from every known source in Aus & NZ (and 2 that won't be revealed, yet) that a set of A7 or A10 cases (other than the above) would cost between $150 & $200 (if they had them).
Being an old fashioned Caring Understanding Nineties Type, naturally I abused him for being a rotten thieving old So & So. The day before yesterday, I rang the wretch once again in an attempt to beat him down to a civilised price. He seemed to take great delight in telling me he had sold them to a "gentleman" in Perth. (I doubt this - We lived in Perth for 7 years and never met any gentlemen)
Instead of lashing out at those dearest to me, I'm retiring to the bottle.
Any suggestions of unique and unsubtle forms of revenge on any of the above will be received with glee.
and thanks Brian, I'll throw a rat engine into it and build the correct one as the bits come to me.
Title: Re: Engine numbers
Post by: RichardL on 23.05. 2009 18:37
Wow! *eek* That must be a really robust house to hold 7 tons of anything in the ceiling. *conf* If he does have a large cache of parts up his stairs (or up some other place), the reason is, likely, that he is just asking too much for them, hence, few sales. If you are still able to communicate with him, you could concede that it appears that you and he will have trouble do any business in the future and hence you will not seek to do so. Then, ask him who will inherit when he goes, so that you can try doing respectable business with him or her.  ;) Of course, once such words are exchanged you would have precluded any future possibility of doing business. (I didn't say it was faultless diplomacy.)

On the issue of knowing if parts bought on U.S. Ebay are good or bad, I had this thought (I hope it doesn't lead to my being overwhelmed but, for now, I can take that chance). Suppose you were to make a purchase on U.S. Ebay with the understanding that you could return the item if not satisfied. As a means of avoiding the costly shipping to AU, you have it shipped to a U.S. forum member (I am semi-volunteering) who looks it over, comments to you, takes detailed photos including specific photos on request. You make a judgement, then the item is either sent to you or returned within the U.S. your risk is the original cost of shipping within the U.S. and, perhaps, you save on charges attached on top of shipping. The original buyer would need to prepay final shipping through the carrier. Sounds complicated and I probabaly haven't thought through all the complications and time involved, but I am willing to try it once or twice to learn if it is, indeed, too much trouble. Maybe no one really needs this, but I thought I'd thow it out there. (Notice I am not suggesting or expecting any fee for this.)

Richard L.
Title: Re: Engine numbers
Post by: A10Boy on 23.05. 2009 20:08
Without wishing to rattle anyone's cage even more.

The reason the BSAOC took the stance they did is that they are empowered and TRUSTED by the UK government's Driver and Vehicle Licensing Agency to administer the legal records of all BSAs which they hold records on - and they have to be whiter than white. As do all owners clubs in their position.

If they gave permission to one person to [Illegally] alter numbers then they would open a huge can of worms as where would it stop, they may as well throw their factory records away and half of us would be riding bikes with Q plates on- it might seem unreasonable to a bloke in his shed with duff cases, but if you think about it, they are correct. Numbers aren't just numbers, they are the identity of the vehicle.
Title: Re: Engine numbers
Post by: trevinoz on 23.05. 2009 22:55
Olev, does the "gentleman" come from Ballarat or closer to Geelong?
The Geelong bloke has complete bikes in his ceiling space, where he built them, and God only knows how he will ever get them out!
He also has a huge shed chock-a-block with A7/A10s and a mountain of parts plus a few cars and I forget what other bikes he has. He had a few square fours but they are all gone.
I had a guided tour through his place a few years ago.
As a matter of interest, he had one of the original A7s, with the centre stand in the frame tube.
He wants top money for anything he sells and is extremely reluctant to part with his cash.
There was a pile of alloy heads you couldn't jump over!
If this lot ever comes onto the market in one lot, the value of bikes will surely diminish.
Title: Re: Engine numbers
Post by: jfligg on 24.05. 2009 00:55
Hi Olev
  I know I guy in Canada that has alot of Plunger stuff.  His website is .  Give him a try.  Good luck Jeff
Title: Re: Engine numbers
Post by: olev on 24.05. 2009 02:03
Manosound, you are worth breeding off!!
I'd take your offer on the spot regarding those cases on ebay, except the chain case looks strange. You could stick your head through the hole where the gearbox seal goes. Looks more like an A65?

A10Boy, I'm sure BSA through their dealer network had a method of providing the original numbers when someone bought a replacement crank case off them, even if it was just for road registration. Maybe the dealer stamped the numbers on and destroyed the original. Whatever, I'm sure it wasn't a big issue back then. The BSAOC are probably a toothless bunch of bureaucratic old duffers anyhow. As Brian said any thought of regarding the museum bike as original is ridiculous and what have they done about the herd of RGS running about. The above is just my observation, I don't really care so long as my engine number contains an A7 to identify it as a 500.

Trevor, thats him, it could be Geelong. What's a couple of hundred kms. The gent from Wangaratta told me he has realised he can't take it with him and is trying to sell it off. Maybe my old negotiating techniques needs refining.

Title: Re: Engine numbers
Post by: Brian on 24.05. 2009 07:57
This thread has raised some very interesting issues.

A10Boy I agree with you that numbers are a vehicles identity and must be monitored, I would not change numbers on anything I owned for any reason. However as Olev says have the BSAOC made any attempt to address the problem of fakes, there are a lot more RGS's and Goldstars around than the factory made. There is no way of checking for the average person when purchasing a bike as the BSAOC will not release the factory records so someone can check. If this information was available on their website then fakes would be easily identified so are they really serious about identifying fakes. I know you can probably get the info from them if you join their club etc but that is not always easy for those of us who live scattered all over the world. Now I am not trying to run down the BSAOC, I am sure they are a very good organisation but if indeed they did approve the welding of a piece of old crancase into another set just to retain the numbers then in my opinion, and I stress its only my opinion, they are hypocrits.

Another way of looking at the originality arguement is this. If you have a totally original bike and you replace the crankcases then you have a bike that is not and will not be considered original even though you have only replaced approx 2 percent of the original bike. On the other hand if you have the front half of a frame and a set of cases that match then you can buy the other 95 percent of the bike at swaps etc and have a bike that is considered totally original. Doesnt make sense.

I'm a firm believer that if you have an original bike then thats good but if not then that should not stop anyone from owning and enjoying the bike they have.

Now I will get down off my soapbox and go and clean my non original plunger A10 that I did a bit over 400k's on today and enjoyed every minute of it.
Title: Re: Engine numbers
Post by: bsa-bill on 24.05. 2009 10:13
New frames came from BSA without numbers, I Know this as I had occasion to buy one along with a new tank and a few other bits following a coming together with a Goldie in 1962.
The dealer did not stamp any numbers on it and I later sold it back to him ( for £175 !!! ) and he sold it on again.
Don't know if that could happen these days though

All the best - Bill
Title: Re: Engine numbers
Post by: A10Boy on 24.05. 2009 12:48
Can you imagine trying to get a reg document on a bike with no frame number these days.

The BSAOC do good work looking after the legal issues and have helped a lot of people who where having problems with obtaining reg documents and validations.

Title: Re: Engine numbers/Frame Numbers...
Post by: LJ. on 24.05. 2009 20:07
Just to throw a spanner in the works.... What does one do if they purchase a bike/frame where the numbers have been ground off with an angle grinder or file??
Title: Re: Engine numbers
Post by: rocket man on 25.05. 2009 13:34
scrap them not worth th hassle mate i bet a lot ove bsa engines
had a con rod throue the drive side case because a lot ove
people then didint clean the sludgetrap out
or change the oil they just used them every day
come what may they didint prise them as much as we do today
and with bsa not being here today it makes the machines we have that bit more special
and in a way were keeping history alive
Title: Re: Engine numbers
Post by: A10Boy on 25.05. 2009 17:06
I'm sure that the BSAOC [in the UK] do their best to keep everything legal, and just by acting as the "Authority", they are helping us keep our prized chargers on the road. Without their help a lot of bikes which turned up in the last 20 years or so wouldn't have been registered, or would have ended up on crappy Q plates. Our government agency in the Uk wouldn't be bothered to sort out records to prove the age of a vehicle, and we the BSA owners would be worse off.

Records are available and they will issue them to members for a small fee, I think its a good thing to be a member, I support them through the membership and they help me via their services.

Its nothing to do with the originality of any particular bike, its to do with Legalities.

There are indeed a large amount of fake Goldstars, but imagine if their was no control at all. BTW, the Goldstar owners club is separate to the BSAOC.
Title: Re: Engine numbers
Post by: jfligg on 28.05. 2009 17:37
Hey olev
  Did you try my friend in Canada?  If so how did you make out?  Jeff