what did i buy? a 500 or 650?

[mario medeiros]

Can't seem to get pics???how do i tell the differance between a a7 and a10 motor? it is a swingarm frame and the top of the tranny say std and the motor has a alloy head?is there a give away between the 2 motors?Thanks

[Brian]

Mario the engine number will tell you.

The number is stamped at the top of the crankcases on the left side, just under where the barrels bolt on. It will either have A10 or A7 stamped in along with some other numbers and letters. If you post the full engine and frame numbers we will be able to tell you what year your bike is.

The frame number is located on the left side frame rail just in front of the fuel tank.

[mario medeiros]

Problem is I can not read either number as someone at one time stamped over them? I was told to count the number of fins on the barrels to tell is a a7 7 fins and a a10 being 8 fins?

[a10 gf]

Welcome to the forum, am hoping you will find all the help you may need.

Info about posting pictures: http://www.a7a10.net/forum/index.php?topic=427.0

An introduction post in 'Bikes, Pictures & Members' is always appreciated by all.

[Beezageezauk]

Hi Mario,

I also offer you a warm welcome to the forum.

You are correct.  The number of fins on the barrel will tell you if it is from a 500 or 650cc engine.  7 fins on an A7 and 8 on an A10.

Beezageezauk.

[bsa-bill]

And another welcome to the gang from NE England Mario
Does it run?

[muskrat]

G'day Mario,  .
With the numbers obliterated it will be very hard to tell how she left the factory (not many are that way now anyway).
Give us an intro in Bikes, Pictures & Members section and tell us about yourself and the bike. A few pictures (a10gf's link will tell you how) will enable us to have a guess at what she is, or pretending to be. The A7's go quite well for a 500 and rev hard, the A10's have a bit more grunt, either will put a smile on your dial.
Cheers

[mario medeiros]

So i now know i have a 650 top end any way of knowing what bottom end i have besides the #'s on the case?

[muskrat]

G'day Mario.
Highly unlikely to have a 500 crank. Rods and stroke are shorter so she wouldn't have enough compression to blow out a candle .
But then again another forum member got one like that and it did run .
Cheers

[mario medeiros]

How is a bsa pre unit a10 titled? By the frame number or the motor number?Thanks

[muskrat]

G'day Mario, the engine # as all frames (bar the RGS) are stamped A7.
BUT an A7 crank, barrel, head, con rods, pistons and push rods can be put on A10 cases to make an A7.
To check what crank you have use a piece of wire down the plug hole to measure the stroke. 84mm for A10, 72.6mm for A7.
Cheers

[KiwiGF]

I recently found out the bsa despatch records are ordered by engine no so its hard for the vmcc uk who have the records to find out when a frame was despatched, its easy with engine numbef for them, but in terms of how registration is done it varies by country, in nz its a vin number attached to the frame, but years ago it was just frame no.

[Beezageezauk]

The UK BSA Owners' Club and the UK licensing authority (DVLA) both go by the frame numbers. 

In fact the BSAOC (UK) can issue a "Dating Certificate" that shows the model and colour of the bike, the actual date it left the factory and the dealership it went to.  These are inexpensive and are available to both members and non-members.

Beezageezauk.

[muskrat]

Same here, the VIN or frame # is the main identifier. So does that mean the only real A10's were RGS's
Cheers

[RichardL]

Bzgk,

Wrote an email with a simple question to the BSAOC librarian about a week ago and still waiting a reply. Hmm?

Richard L.