New member 1948 A7

[stephenrc45]

I don't know what I have! As far as I can see the only other rigid parts I have are C10 bits, frames engines etc.

I only have one A7 frame and thats all one piece which going off the frame number makes me think its a 1948 one.

If your only in Somerset your welcome to pop down and have a root around. I got left a lot of this stuff by my late grandad and while I we both used to have great fun restoring and racing the BSA's some of it I just have no idea about. I don't think there are any other A7 parts though. Just this one bike in bits. But then it does seem that I have a few to many oil tanks!

I will also be up at the Bath and West auto jumble in a couple of weeks too.

[trevinoz]

Stephen,
                 Do the petrol tap sockets point back at an angle or are they vertical?
As far as I know, the long stroke tanks should have the angled sockets.
Trev.

[stephenrc45]

Yes they point backwards maybe 15% from the vertical.

[Brian]

There seems to be few variations in these tanks. The longstroke tanks have the taps at the rear and are either angled slightly or straight down, the ones on my Star Twin are straight down. The rear mount on the longstroke tanks is a full circle whereas on the later tanks it is slotted. The latter (shortstroke) tanks have the taps further forward.I have seen a tank that had the full circle rear mounts with the taps further forward but that was only a photo, I didnt see the tank in the flesh so it could have been altered.

A one piece frame with a Y prefix is 1948.

I've added a photo of a 48' A7 owned by a friend, this bike is totally original and untouched. Interestingly this bike has matching frame and engine numbers.

[stephenrc45]

Thanks for the picture and for everyone with their input.

EDIT:

I've just been down to check the tank again. Yes the rear mounting hole is round and the front elongated with both taps facing slightly backwards.

Thanks to the forum I've managed to work out which two wheels belong to the A7 rather than the plungers. The none splined side isn't as wide and the pressed on cover isn't as big as far as I can tell.

Plus while hunting for the wheels I found another large box with A7 parts in it, 2 more cylinder head (one has had all the fins cut off it but the other is stock) 6 pistons, a couple of rocker box sets, some footrests a few idler wheel and some cam shafts. There are 4 sets of cam but looks like only one set is worth anything. That might well come in handy if the set in the motor are less than perfect.

It looks like at some stage the bike/engine has been raced as all the rocker have been polished and the idler wheel drilled, I guess its been run on dope or something for the cylinder heads lack of fin. There are also some rather high compression looking pistons in there that show rather large signs of abuse!

I'd like to restore the bike to standard but the pistons I have have a rather large crown on them compared to the flat toped ones shown in the manual. Are these likely to be Star Twin pistons? Best I take some more pictures I guess.

[terryk]

The longtroke pistons were fairly domed Std they werent flat like the latter A10 etc

[trevinoz]

Don't get your long stroke and short stroke idler pinions mixed up.
They are the same but have different timing marks.
Trev.

[Brian]

I can vouch for that !

Curiosity got the better of me so I pulled the gear out of my spare longstroke engine. Turns out there are 4 teeth different. The gears are identical in every way except the longstroke one has 16 teeth between the dot and dash and the later motor has 20.

So anyone who has a mix of long and short stroke motors it would pay to count the teeth before using a gear, its easy to get caught if you dont know about this, I did.

I've also added a couple of photos of longstroke pistons which may help you identify them. The one on the left is a std 6.6-1 piston and the one on the right is a 7.25-1 Star Twin piston. You will be able to see the two are almost identical except the Star Twin one has a slightly higher crown.

[stephenrc45]

Thanks for that.

My pistons look standard.

 On a nice note, I pulled the bottom end apart. All the cam followers look brand new as does the cam. In fact I'd be surprised if it had ever been run. Cam is part number 67-695 which I think is right for the year. I haven't taken the rods off yet but the timing side bush is also brand new with no signs of ever being used. Someones spent so time on this at some point it would seem.

I'd take some pictures but the camera battery has decided to give up now so I will too.

[stephenrc45]

Managed to get the camera to play ball.

One of the pistons and the cam (its a relief its not worn out like the other 3 I found).

[terryk]

Yes thats the cam some of them didnt have a number on the end just a large centre drilled hole. These cams always seem to be worn badly so you are very lucky with what you have. Well done.

[stephenrc45]

Bikermike came  down to see me today and we managed to clear up a few questions. I'm glad I held onto the bike now as 12 months ago I did advertise it but got little response.

We sorted out the mudguards etc so at least I know whats right and whats not.

[RoadRunner]

Hi,
A really interesting thread!
I've just got hold of some ZA7 cases (long stroke) with reground crank (needs dressing), new shells and bush (but no rods) however, now undecided whether to attempt to build a whole engine given some of the 'issues' getting parts (ie. camshaft). But If I do at least there's lots of knowledge out there! Keep you posted.

RoadRunner

[terryk]

There seems to be plenty of SH longstroke engine stuff on ebay from time to time.

[vagabond]

I am really enjoying this thread as it is my ambition to build or at least attemt to build a 48 rigid a7.
Please let me know how you are getting on with it and if you have any spares left over going begging.
IF i cant find all the bits i will have to build a plunger Dave (Sheffield)