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Messages - Calum

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Bantam / Re: Brake drum skimming
« on: 20 March, 2021, 22:34:17 »
I can skim a brake drum no bother but I don't fancy machining the linings... nasty stuff! There is a firm that does the lining work but I can't for the life of me remember at the moment who they are... If I remember I will post back!

Some drums dont like being skimmed from memory, are these the magnesium alloy ones? I seem to recall they have a hard layer where the shoes run, which once removed (machined off) exposes the soft alloy underneath which doesn't last long at all.
Am I completely making this up or did I read something like that? New to the classic bike scene all I really know is cast iron drums!

Singles / Re: Interesting (non-BSA) bike
« on: 20 March, 2021, 22:27:11 »
I've just read that too. I knew OF them but don't think I've ever seen one in the metal. Transverse kickstart is novel!

The Star and Garter / Re: BSA C15 Light switch screw
« on: 19 March, 2021, 20:20:22 »
Hi Dave

Apologies for the delay. As best as I can measure and compare against a tap for the pitch, I can confirm it is indeed 2BA.


Singles / Re: B33 plunger centre stand
« on: 17 March, 2021, 13:04:59 »
Can't attach a photo to a PM it seems!

Twins / Re: Oil leak confusion
« on: 15 March, 2021, 09:51:34 »
It is a bit confusing! The CEI threaded components that we have on BSAs (mainly 26 TPI but also 20) need Whitworth size spanners. The spanner size relates to the shank diameter not the head.

BSF/UNF/UNC spanner sizes all relate to the measurements 'Across Flats' (AF) so use common spanners although they have varying thread profiles.

To make it more confusing, there are some sizes where one spanner size is near enough to fit both Whitworth and (e.g.) BSF.

This link may clarify!

My suggestion would definitely be to invest in a set of Whitworth spanners.

Finally.... You will find that you can't get a socket on to some of the head nuts and an open-ended spanner can't get the torque. In which case I suggest getting one of these: it's metric but adjusts to grip and does a good job!


BSF use the same spanners as BSW. For post war fasteners, the same diameter thread in both BSW and BSF use the same spanner size. Prior to that, the Whitworth fastener would have a bigger head than a BSF fastener of the same diameter. Hex sizes were reduced to save material, and never changed back. What makes it confusing is the markings on spanners never changed - even brand new ones will say 5/16" Whit for example, when in fact it will fit a 3/8" Whit bolt and nut (and 3/8" BSF, which the spanner will correctly state)

Unified series threads (UNF/UNC etc) use AF spanners, as you say across the flats sizes.

CEI (later adopted as BSCy) should use BSW sizes for the head flats, but I've found a mix on aftermarket nuts between BSW and AF size hex (should be the former on standard fasteners)

Singles / Re: Magneto Habits?
« on: 14 March, 2021, 09:02:17 »
My B31 tends to like the timing retarded roughly half way on the lever to start (mine is a 1953 build, taught wire advance as original). Retard it any further and I can't get it to go. I've not once had it kick back so it might be too retarded full stop? Runs and goes well though when fully advanced. After I've started it I advance it pretty much straight away. Once warmed through I can retard the ignition to a nice bob-bob-bob slow tickover. I'm not totally sure the timing is spot on as I haven't checked it yet - it's a job on the list before I get back out on it but it seems pretty good (I already reset the points and plug gaps, cleaned the pickup etc).
Do bear in mind I've only had it a few months so really not sure on its 'behaviour' yet!

Twins / Re: Are these fuel tap corks especially designed to leak ?
« on: 13 March, 2021, 22:12:53 »
Good morning,

I think I need to drink some wine and make some fuel tap corks.  Not at the same time though.
The corks are available for a lot less than 7 but with a wine cork the quality is probably better.  One problem though is how to get the cork out of the bottle without using a cork screw as this will damage the cork.
If you do this wear a mask as the dust from the cork is likely to be harmful if inhaled.


You'll have to take to drinking champagne!

Much better than that would be a cork from the stopper on a single malt bottle... no corkscrew damage.

I made a new cork seal/bush from a wine cork for the Whale tap in my old 60s camper, worked a treat!

The Star and Garter / Re: BSA C15 Light switch screw
« on: 10 March, 2021, 12:43:43 »
I had a quick look at my spare switch and I am pretty sure that is what it will be. I can measure for you if you need to order a screw only to find it might not fit!

Singles / Re: B33 plunger centre stand
« on: 10 March, 2021, 12:02:46 »
Yes can make one of those and post it to you no problem. When I sat and looked at it with a fresh set of eyes it was obvious how it should work - my original assessment was based on what I had inherited from a previous owner (which is obviously wrong, although it does work) but when I mentioned it earlier or became obvious how it should be.

Let me know the length, OD and ID and I'll turn one out of some steel.


Singles / Re: B33 plunger centre stand
« on: 10 March, 2021, 09:50:57 »
The stand on my B31 plunger has a bronze bush in it through which the stud passes, not sure if this is original or not (probably not as whoever had fitted it hadn't drilled through for the grease nipple!) It came with the bike, but unattached and with the old pivot seized in and cut off. I shelled it out and removed it, reamed the bush back to something like and made a new pivot pin to suit. As usual, the frames were worn so I made top hat steel bushes to go into the frame holes which were dressed until they fit nicely and the pivot bolt passed through with minimal play. Worked nicely in the end, and saved me welding the frame holes up.

I can turn you a bush in steel, bronze or whatever you like. Where abouts are you?


EDIT: thinking about it is the tube supposed to be a crush tube so the stud tightens up hard on it and the stand pivots around it? Possibly. I can't remember what I did to get the nuts to tighten now. The bush was so tight in my stand I assumed that where it should be. Would also explain the lack of grease hole in it if the tube is supposed to be stationary with the frame (oops!)

The Star and Garter / Re: BSA C15 Light switch screw
« on: 08 March, 2021, 22:17:28 »
Total guess... 2BA? BA is incredibly common in electrical fittings, especially old Lucas items too. Is this the 'usual' Lucas rotary light switch? The screw that retains the knob on top?

Twins / Re: BSA A50 broken sump stud removal
« on: 08 March, 2021, 17:58:43 »
Not a fun job with the engine in the bike. Any broken studs into alloy or other soft metal I really like to get them set up securely on the pillar drill and drill out the stud to the core diameter of the thread. Done accurately, you will be left with a little spiral of steel much like a helicoil which removes easily enough with a scribe or small pick. Not much help in your situation mind you...

With it in the bike a stud extractor is worth a shot. Hopefully where it is it shouldn't be corroded too badly into the casting as it'll be all oily (are they tapped right through into the crankcase or are they blind holes?) so I think you stand a good chance with an extractor. Another way to get a snapped stud moving is to punch them round anticlockwise but not recommended on something so small and surrounded by nice soft aluminium...

I assume it has broken flush with the casing?

Twins / Re: Oil
« on: 08 March, 2021, 17:50:43 »
For the Gearbox, if you use a gear oil say EP 80, specify the 'Yellow metal' compatible one as the standard EP has an additive that the bronze bushes don't like!
GL4 spec is what you want - GL5 has too many sulphates in it which leach the copper out of bronzes (so far as I understand it). Many people will tell you they have ran GL5 for years with no I'll effects, but given GL4 is just as easy to find and no more expensive I don't take the risk. I believe GL1 grades are still available from agricultural dealers etc but I've never had any experience with it. I would guess it contains even fewer sulphates (and so smells even less eggy!)

Indeed as Bess hints to above, gear oil weights aren't the same as engine oil weights, which is really handy  :o

Singles / Re: A crack in the cover
« on: 04 March, 2021, 19:19:54 »
If you want to retain it then get it TIG welded and skim the mating face to get rid of any distortion (or file it flat with the aid of a surface plate, pane of glass or whatever you have to hand to use as a flat surface to check against).

Otherwise you could replace it? They aren't uncommon.

The Star and Garter / Re: Head Gaskets
« on: 03 March, 2021, 12:54:32 »
:) :) :)

I've jut re-read the info on using a spanner on the end of a torque wrench. My thoughts the fulcrum/break point is in the same place are we really extending the arm????????? I dont think so but I shall be advised as usual.

Mike 8) 8) 8)

Yes, you are. To make it simple for the maths side though you must keep the spanner in line with the torque wrench - angles are doable but require a little more working out.
Now imagine it with spanner in line as one long lever. For a given torque, we all know that the further out from the centre you go the less force you need to apply. The bolt/nut is your new fulcrum point, where the torque wrench clicks doesn't really matter, but the reading on the wrench itself is only calibrated with the square drive over the fulcrum. With the centre of the turning moment now further away the setting will be lower.

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