1951 BSA Engine Specs

The pages above are from a small book entitled "BSA Motorcycles for 1951 - DATA BOOK. Private and Confidential"
From that it must have been a dealers only publication, not for consumption by the paying public. The thing that is interesting is the figures for the B34, they are identical to the B33, even the alloy head and barrel are optional extras! On the other hand, the B34 GS is a completely different beast, very much a customer specced bike individually built to order. This must have been the case as the permutations available with cams, compression ratios carbs etc. would have made it impossible to have done it any other way. So it is then, unless the cases are stamped GS it ain't anything special and it certainly did not leave Small Heath as a Gold Star.

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As you can see along the right hand edge of the second page this book contains virtually every specification for all 1951 BSA models. If you want to see any other pages leave a comment or mail me.

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Better Than Good

Tried to phone Chip yesterday, looking for the fabled Gudgeon Pins. After a couple of failed attempts, the penny dropped, 29th of January, Kempton Jumble, that's where he'll be then. Chip's the sort of bloke that may well have an odd pin or two at his disposal, a phone message and another call this morning revealed that there were indeed a pair to be had. Went 'round there and then it just got better, the pins were still in the pistons and the pistons, with the rings, were still in their boxes. Seemed a shame to remove the pins and break up the set, and when the crowns were read it said +0.020". Which is, coincidentally, what is written on the ones back at Ironworks HQ, the deal had to be done and was soon sorted.

Comparing them to the existing set show them to be at least a ratio higher compression, so a little more bang for the buck as well. Not sure whether SRM will still need the pins, as they are new and therefore the exact same diameter as a later A7 0.6875" so any new little can be honed to that, I would have thought. That remains to be seen tomorrow though.

Chip's main input to the cause is reconditioning Lucas Magnetos and Dynamos for both singles and twins, and sends them out in a fully restored condition. If you feel that your ride could do with better sparks or fitter Glow Worms in the front, he can be contacted on +44 (0)1462 623687.

To clear up any confusion........................

................ about yesterday's post about stripping the gearbox and not knowing anything about it's history. The gearbox being rebuilt is not this one, this is the one that was originally in it when the bike was built up 30 years ago. Apologies for some of the rough fixings used, that happened in the intervening years and better discussed over a pint than go into it here.
The box currently being worked on, is another one I picked up along the way and it seemed a better option than having all the chrome stripped off of this one. Some bits of the gear change and kick start mechanisms will have to come from here though.

A Little Bit More Grief

When I sent the rods up to SRM to have the big end eyes honed I mentioned in the note that I want the little end bushes checked, and replaced and honed if necessary. I got an e-mail back asking to send the gudgeon (wrist) pins up for measurement purposes if new ones needed to be fitted. Got them out and ready to send, it was then it was realised that one of them was corroded, what was thought to be shit turned out to be a corroded line. No probs phone up SRM and say carry on with two new pins, er no! Long Stroke A7 pins, ain't got any, can't get any. A few phone calls to other suppliers didn't turn anything up either, although Mark at C&D Autos said he was going to check his Hepolite catalogues over the weekend to see if he can cross reference the dimensions.
The dimensions are 2 inches long and 11/16" Diameter, don't know if anything like 500 Triumph might fit.

Still it's not a show stopper, there are some somewhere.
The old rocker boxes were stripped of the rockers, spindles and studs and these were transferred to the NOS boxes bought some time ago. Not much of a step forward but a step never the less.

Smiffy was spraying some of his Vincent parts with some kind of heat proof 2 pack, managed to slip the barrels in whilst he was at it. Very shiny and it lasts on his Vin so all should be good.

Stripped the gearbox out ready for blasting and polishing. The condition of the gears and shafts in the main case do not seem to match that of the gear change mechanism. There is very little, if any wear to the gears or shafts and everything wiped clean and pretty much looked new in there. To such an extent that it may have been fully rebuilt very shortly before coming off the road. The gear change mechanism is partly missing and the outer cases look to have had a hard life, completely at odds with the rest of it. It is very possible that at some time the kick start/gear change end has been swapped with another to keep a bike on the road leaving the main section un touched.

Girder Forks

Although not really at project status yet, these came yesterday for the B33. Not off of a Beezer but a 30's Motobecane. Strangely enough a Model B33, they're all there except the handle bar clamps, even the bearing races on the stem are present. Probably have to run a 21 incher on 'em as they come up a couple of inches short compared to Tele's, but that ain't a problem.
Big thanks to Roland for going a long way to making it happen.

Junk 2 in the works

Whilst Billy is setting his keyboard alight due to frenzied typing action, I thought I'd post this flyer for the second issue. Bigger than issue 1 it promises to be a killer judging by the lineup.
If you missed out on issue 1, don't wait until you see it on The Bay of Fools in a couple of years and think "Bastard, I could have had that!" e-mail me now and we can work something out.

Cool Triumph Site

Nowadays the blogscape is full of cool bike and custom orientated sites, some better than others, some you follow, some you don't. One site that I keep a careful eye on is 6 Shooter, if it's quality Triumphs that float ya boat, then it should be a regular stop for you as well.

This frame is the bones of the latest project, made by Elswick Cycles in record time, around a week!

This discrete stash tube is as cool as a Polar Bear's scrotum, who knows what you could keep safe and sound in there.

So if you are a Trumpet freak, get over there and add it to your list.

On the up side

Picked up the disc from Stotfold Engineering this evening, funny but whenever I go down there it's pissin' down with rain. Anyway, here it is, drilled and re-plated, although it still needs a bit of detailing, it's looking far more like it. There is an added bonus, in as much as the hub detail and polished spoke heads are visible through the large centre holes. The difference in weight is definitely noticeable as well, compared to when it was more like a dinner plate hanging on there. Technically speaking it should improve the ride a little as - if I remember correctly - it's the ratio between the sprung weight of a bike and the unsprung weight that is the controlling factor. The higher the number the more compliant the suspension is, that's why things like Electra-Glides and Gold Wings are smooth rides.

A Slight Delay

Didn't get any further with freeing up the Drive Side big-end yesterday, so the rods are going away for a touch of remedial therapy. I'll get both honed to try and maintain the balance between the two. The comment by Billy Whiz on yesterday's post shows that it is a known problem. This is backed up by the fact that big-end honing is offered as an engineering service by SRM.

Decided to fit the crank into the cases anyway, just to ensure there are no nasty surprises there when the rods come back. They went together well and the new bush appears to be as good as it looks, so that's a result.

The cases are only nipped up as can be seen, but the crank spins freely enough to say "The jobs a good'un!". There's still plenty to be getting on with whist we're waiting for the rods to be sorted, so the time will not be idle. The gearbox needs looking at, or checking over at least, the head needs to be cleaned, painted and reassembled and the rockers and spindles need to be stripped out and built up in the NOS rocker boxes.

If you open this picture up and look just to the left centre of the chain tensioner studs, in the middle of the primary inner, you will see a number stamped there. This says 20-1-54, and it has been done with stamps in a proper holder and not individually stamped by hand. The engine number shows the motor to be 1948, I think this later date indicates that the motor had been back to the factory for a rebuild at that time. There is also a small letter "A" beneath the main engine number, again mysterious, but perhaps there to externally show that the motor had been rebuilt by the factory.

Progress Halted

The logo for this site is a con rod piecing a heart, didn't realise how right that would turn out!
Started the engine build yesterday, got some of the studs out of the old cases and installed in the cleaned ones, fitted the ball bearing on the drive side, swapped the scavenge pipes over, everything going along fine. Fitted the new -0.010" big end shells into the timing side con rod and torqued it up to 10 lb-ft no problems, the rod spins on the crank as smooth as silk. Fitted up the drive side the same and it's tight, checked and cleaned everything again, still tight. Removed the assembly from the timing side and fitted it to the drive side and it's fine, so the journal is OK, the problem must be in the rod itself or the cap. 5 hours spent trying to find the reason, and still not there. Start again this morning, if we can't find it then the rods and end caps will have to be ground on the mating faces and re-honed to size I reckon.
Still, if it was easy they'd let women and kids do it.

Gold Star BB34 and DB34

Not being able to get on the A7 motor build until I get up Johnny's tomorrow has been twisting my melon this week, so thoughts today have been on the B33. I fancy putting a Gold Star top end on it, more for appearance than performance, but a little more get up and go is never a bad thing.
Most people think of the 500cc DBD34 Clubman, the classic Cafe Racer, when they think of Goldies, but BSA were very successful in the States with them, both off-road and on the half and one mile flat tracks.

The big finned motor seen above first appeared in 1954 as the CB series, this lasted for a couple of years until the DB's arrived in 1956.

Before '54 were the smaller finned ZB series in a plunger frame and the BB in a swinging arm frame. It should be noted that it's not a Gold Star unless it has the letters GS as part of the engine number.
Personally, I prefer the look of the earlier BB engine where the pushrod tunnel is still exposed, although the behemoth proportions of the later barrel has a certain charm.
So, word up people, I am now officially on the hunt for an early alloy 500 Gold Star top end. Rare as rocking horse shit I don't doubt, but if any of you fine folk who take the time to read this drivel know the whereabouts of such parts I would love to know.

These two early advertising brochures clearly show the difference between the two types of head and barrel set ups.

Engineering Master Class

Grab yourself a beer, maybe two and fire up Flashbackfab make sure you've got a couple of hours to spend checking this out. Paul Brodie pretty much made a replica Excelsior Board Track Racer from scratch, this is not a scale model, it is the real deal.

Below a view of the valve gear, all designed and made by Paul.

Prepare to be amazed and humbled.

Two Dicked Dog

At the moment I'm like the proverbial "Dog with two dicks" can't wait until Saturday to get up Johnny's and get stuck into building the motor up. Terry from Stotfold Engineering kindly dropped off the cases and crank yesterday. As I've said before, the cases are amazing, they really do look new, and the fit of the bush he has made to the crank journal feels spot on. My only fear is that somewhere along the line some part will be missing, or there but not fit for purpose and the job will be held up. In reality it could all be in Wales at the moment, out of my control and at least two months away from coming back. I've tried to pre-empt the parts we will need and get them on order from Draganfly but the problem is that the drawing on their site (above) is generic. The actual picture shows plunger cases and the part numbers cover all models. The long stroke motor was only made between 1946 and 1950 and there are quite a few subtle differences between it, and the more common plunger engine. It can be a little difficult at times trying to discuss these differences over the phone and be confident that the right parts will turn up.
We'll see.

Good Stuff Waiting To Disappear

A few bits arrived this morning from Draganfly, the Drive Side main bearing, -0.010" Big End shells, new con-rod castellated nuts and some crankshaft shims. The cam followers I've had for a while and are NOS parts. The completed cases will be back either today or tomorrow so with a fair wind the bottom end should be back together this weekend, that's if I ain't forgotten anything that is.

Mister I's Bonnie Chop

Went over and looked at this yesterday, first started talking to the ol' boy about it back in August. The bike used to belong to Mister I, who built it back in the late Seventies, only it was blue then.

Used to have a pair of those flame cut girders on it that must have been a bastard to steer, just on the weight of 'em alone. Now there is no front end at all with it.

I've never thought that the Oil In Frame Trumpet lends itself to hardtailing and I reckon that this pretty much proves the point. So strike one, the frame would have to go. There is a V5 (registration papers) with it, and the motor looks alright, and the price was right.

Then the story of the motor unfolded, the cases are early 650 and the crank and top end are 750 T140, I didn't know it but the drive side main is a bigger bearing on the 750, meaning the cases have to be bored to accept the later main.

Problem being, whoever did it got carried away and went too big. The drive side main is now held in by shim and some kinda plastic metal stuff.

Ah well, time to have a cup of tea and talk about something else then, cos there ain't nothing doin' there.

Wizards in Oz

Came across this bike shop down in Sydney, Australia. Trojan Classic Motorcycles, are flying the British flag with taste and talent. Checkout their site for lots more of what you see here.

Not just hot totty on there, there are some great build posts.....

..........and engine rebuild sequences.

Back Wheel Back

Smiffy brought the back wheel 'round yesterday after re-lacing it, looking pretty damn fine. Following the lead set by the front, the nipples are brass and spokes stainless. When it was bolted up in the frame it was found to be 3/8" out towards the Timing Side, so it was time for adventures in wheel building. Smiffy said he'd do it later, but I thought I'd give it a go and got down to it. Pretty easy thing to do as it goes, slacken all the spokes by half a turn on the side the rim needs to move away from, and tighten up the opposite side an equal amount and across it goes. It only moves about 1/16" at a time but remeasure each time and do another lap of the spokes as called for, and it will move over in a controlled fashion. Got it pretty much "cock on" for centre with about 1/8" run out, Smiffy can do the final tweaking to really true it up.

Found a nice brass grease nipple (zerk) in the box o' shite and got that in there to mirror rhe spoke nipples. As Frank Marino said "Happiness is beginning to rise"

5 Service Stars

As I mentioned the other day, the new timing side bush is being sorted at Stotfold Engineering. True to his word Terry called in and picked the cases up Wednesday evening, along with the front disc that will be drilled out to a similar pattern as that one shown a couple of days ago. There's a bit of a bonus with that, his brother does plating and will hard chrome the disc after it's been machined.
Anyway, I called into Terry's place this afternoon just to make sure that he had everything he needed for the bush job, and secondly, and hopefully, that he wasn't going to say "They're scrap, can't do anything with them". Got 'round there and went into the office with him, and Say What ?!!!! the cases are done!
Vapour blasted, a couple of cracks welded up, all the screw holes cleaned out and the bush made, fitted and bored. No pictures as yet as I couldn't carry 'em on the bike.
Had to get home pretty damn el rapido to order up the Roller Bearing for the Drive Side and some shims, ready to get that sucker back together.
Oh yeah, I found myself whistling happy tunes on the way home as well.

Sublime Work

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I know I can't leave this alone, but it's the first time I've seen these pictures. Ya should open these pictures up, soak it in for a while, go down ya shed, take it to bits and start again.

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Trailer Queen, Show Boat call it what ya like, I honestly can't see it getting any better than that, not at the moment anyway.

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SF750

Can't say I've seen too many of these done before. Laverda SF 750 Twin motor, for sale in France now for a couple o' grand! Interesting I'd a thought, make a nice Brat stylee thing, there is no front down tube on 'em , and the motor has a big Honda CB77 look to it, all hangin' out the front like that.

Motorcycle Engineering

It's time to start the motor rebuild on the A7, from the floor of the cellar to the top of the chimney pot so to speak, everything must be checked, corrected and sorted. Anybody who is familiar with BSA's range of twins will be aware of the problems that can occur with the timing side bearing. Instead of a normal ball bearing as fitted on 650 Triumphs, BSA, in their infinite wisdom, persisted with a phosphor bronze bush. It is through this bush that the oil feed to the big ends must transfer, through the side of the bush and miraculously find its way into a spinning crank that may be doing 6000 RPM. It does work, but the importance of clean fresh oil, regularly changed, cannot be overstated using this system. There is a modification available from SRM, suitable for post 1952 twins, this motor is the early 1947 Long Stroke and there is not enough "meat" around the bush to take the machining necessary for the conversion. So it's a new bush, no other option available.
The new bush is pressed in during which the bore reduces, going tight, the bore is then resized to suit the diameter of the crank. BSA used to supply a tool so that it could be reamed to size using the drive side main bearing as a support and guide.
Nowadays the case half is clamped to a table and the bush is either jig bored or honed to size. Not a job for anybody with an electric drill that's for sure, I was lined up to get it done at Draganfly in Suffolk but the bloke decided enough was enough and retired at Christmas. After phoning about it looked like SRM in Wales was the best option, so it was going to be a 400 mile round trip on Saturday, early kick off as well because they shut at 2.
Looking on here Sunday, at front discs I came across this SITE.............

........... and thought that there must be a Stotfold in the States as well, as it is only a few villages away from her else. I fired her up and Lawks a' Lawdy it is Stotfold down the road!!! Only it's now in Biggleswade which is up the road as well, just the other way, never heard of 'em ever. Anyway, looking at the site and the bloke's Commando.................

........... I figured I best give him a ring on Monday.
What a result, after speaking to him for a while it was pretty obvious he knows what I'm talking about and keen to get on with it. I whipped in to see him on the way back from The Salt Mine in the evening, Terry, for he is the bloke, is into his bikes major league, small racing stuff is his bag, but other than that it's bikes, bikes , bikes other than bikes that is. Weird shit, never ever met him before, or heard of the works, which is full o' machinery. The addy is The Old Forge and it doesn't disappoint, pics to follow.
So the cases are going over there pronto and we'll see what the outcome is, but it's exciting times people!!!!!!!!!!

Smiffy's Vincent

Popped 'round to see Smiffy over the weekend, he's just putting his Lightning back together. Very nice indeed and probably worth a hundred quid more today than it was on Saturday!
Stevenage, the site of the old works, is only ten miles or so from here so there are probably more per square mile in this area than just about anywhere else on the planet. It's reckoned that in the 50's a hell of a lot of people 'round here were running bikes of all makes with Vincent, tanks, wheels, mudguards and just about anything else that could be sneaked out of the factory on 'em.

The man has got a great eye for detail, and his bikes give the impression that nothing is put on without being studied, modified and massaged first. Which is of course the way it should be, but it's only a few that carry it off throughout the build.

The bare bones of his Trumpet Bobber project was tucked up in the back corner, getting attended to as and when the right parts turn up. This promises to be a sweet bike when it's finished, in fact it's guaran - damn - teed it will be.
I'll keep y'all posted on progress.

Commando Disc

As the front end on the A7 is originally from a 1975 MkIII Commando it runs a (not very good) disc brake set-up. There are loads of upgrades out there, but they nearly all require a new caliper and rotor to be fitted, and these tend to be modelled after modern bike brakes. I like the original caliper, big old clunky cast aluminium thing that it is, it seems a little more in keeping with the overall feel of the A7 as it stands. Looking 'round to get a new standard disk I came across this at Old Britts in the good old USA. Cheaper to have the original disk ground and drilled that to buy a new one, until you take the cost of postage into account! Hmm, wonder if there's anybody in England doing the same?