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#16
Quote from: Rupert on 18 February, 2022, 18:08:16
It may be more a question of do the followers and the inserts they run in really need changing? If the followers go up and down ok without excessive side to side play then leave well alone?

There's a lot of side play with the inlet follower particularly but, more importantly, they really need to be in another (half decent) crankcase casting.

Quote from: Rupert on 18 February, 2022, 18:08:16
There's one correct original cam follower on eBay at the moment from dynamo dunn, so you can at least see what it looks like. Item 325015367365

I'm slowly getting to grips with this now; I've been scouring the parts book looking for something that looks like what is already there but, of course, it's another red herring!   I have already seen that follower when searching EBay but it looked completely wrong (i.e. completely different to what is in there already) - now I know why!
That would also explain why the tappets were so difficult to set as they are partially located "up the tower" and not nicely in the chamber intended for them.   So I'm guessing that another PO modification was custom length push rods to accommodate the over-length  and bushed cam followers.

Do you know what the significance of the partly helical holes are?   Is it to reduce surface area and thus friction, maybe to impart rotation of the follower to spread the wear?  Any ideas?

Anyway, thanks for you help, now at least I understand what should be there so I now have a couple of options 1) try and restore it back to the original (parts permitting) or 2) contrive a similar replacement system to that that is present using more freely available M20 parts (for example).

Cheers!

Alan
#17
Quote from: Rupert on 17 February, 2022, 12:44:37
There's no accounting for what may have been done to your engine before in terms of butchery and non-standard parts having been made to fit.

And that is definitely the truth!   Many and various of both acts of butchery and non-standard parts.   You'll see an example of the former in the following photograph where a big chunk of the casting is missing (one of many missing bits of casting).

Quote from: Rupert on 17 February, 2022, 12:44:37
Correct re the principle of how the tool pulls the guide up and out of the casing. I put a tapped hole in the shouldered collar for the bolt to screw into rather than using a nut under it.

I could possibly drill and tap a hole into the top surface of the guide alongside the cam follower stem? - see next point ....

Quote from: Rupert on 17 February, 2022, 12:44:37
Correct the cam followers have to come out first. What is stopping your cam followers simply lifting up and out of the guides? Removing the cam spindles to allow the followers to come out downwards shouldn't be necessary.

The cam follower itself has a circular head with a flat surface that bears on the cam. The head is a larger diameter than the stem and therefore can't be pulled through the bore of the guide.  I'm not certain that even if the cam spindles were removed you could get the followers out that way as I think the head will foul on the crankcase casting itself.

Quote from: Rupert on 17 February, 2022, 12:44:37
On no account risk damaging an irreplaceable cam follower by using it in some other way!

Yes that is an excellent point indeed!   Try as I might I haven't seen anything that looks remotely like my guides on EBay etc.   The followers look to be a similar style to those for B33 (See second photograph borrowed from  EBay) but the guide is completely different; there is no threaded part (I presume as I can't see it!) and there is definitely no hex to unscrew it.     Having said that, I can't tie up what is in my engine with the Parts Book for the year (1939) but then I don't fully understand the parts book anyway on this particular subject!

Quote from: Mike Farmer on 17 February, 2022, 13:24:52
---but if you turn the cams, do the cam followers move.

Yes the cam followers move just fine, driven by the cams when fitted or a finger when not.   The guides are worn so the followers have some side play (mostly at the top of the stem) but I need to be able to remove and recover the followers as I probbaly will replace the crankcase casting for one that isn't full of cracks, bodged welds, holes where lugs have fallen off and been fixed back on etc etc.

Anyway, thank you very much for your continued interest!   I will get to the bottom of it but probably not very quickly.

Alan
#18
Many thanks for the reply.     

Do I understand you correctly; the bolt passes through the plate then the hole in the guide  with the nut on the underside i.e. closest to the cam and pulls the guide out as the nut/bolt are tightened against the plate?     

My guides seem to be in 2 parts; 1) a thin wall brass/bronze tube fitted into the bore in the crankcase casting and 2) the guide bush itself * which presumably is a a good fit in the thin wall tube and this has the bore in which the cam follower shaft runs.     

If my understanding of your description is correct, clearly the cam follower has to come out first which means the cam spindles have to be removed.

I have another similar casing that has the thin wall tubes fitted but no guide bushes.   Both cam spindles are intact and don't look like they've ever been removed.

Could the cam followers themselves with suitable thread extensions not take the place of the bolt or would that be sacrilege?

Sorry for possibly being a bit dense here!

Alan

* In-fact my exhaust guide seems to have already been gotten at in a previous life and actually appears to be a steel bush with a thin walled bronze tube inserted.  You can see this in the the second photograph.
#19
Pre War / Re: B21 - So what exactly have I got here?
13 February, 2022, 09:20:04
Thanks,

Yes I've been in  touch with a chap, Russ,  who  I saw did a wonderful job on a James gearbox casing recently - amazing results he got with that!   I will be asking him to work on "some" castings although I think I will probably sacrifice the original timing side one - it is so poor in so many ways.   As the bike is far from completely original, I'd  rather re-build the engine with a good basic casting than something that's got more Elastoplasts on it than all that and that's before any remedial work is done.   

I can't find a video, but here are some photographs of the amazing job he did on that James gearbox.

https://www.facebook.com/BadFootCustoms/photos/pcb.284372720459715/284370690459918/

#20
I need to remove the cam followers and guides from the B21 engine.   Most of the later ones appear to have the guides screwed in and, most importantly, they have some flats on by which they may be tightened and loosened.

The B21's guides seem to be sub-terrain and smooth; no holes or flats to get a grip on.     

Any ideas on how they are held in and how they are removed?
#21
Pre War / Re: B21 - So what exactly have I got here?
12 February, 2022, 12:55:16
Well I think I can safely answer my own question now and the answer is .....

     A Dog's Breakfast

The machine is clearly a bunch of worn out old parts, scraped up thrown together and called a bike (matching numbers though so all is well ...).   Nowhere is this more true than in the engine department.    You may recall after initial running it seized and I re-built the top end when I found it had a Triumph high compression piston, what looks to be an alien conrod and when I measured it a CR of approximately 11:1!    You may also recall that I found a replacement low  compression  +0.02" piston, had the barrel re-bored and made a thick copper head washer which got the CR down to something under 8:1.   Well, despite careful running in it seized again a few months back but this time it was obvious that nothing but a complete strip and re-build was required although this is completely new territory for me.  When I finally bit the bullet and dove in things started to become clearer.

When the crankcase was removed and separated it soon became clear that the crankcase castings had had a very hard life indeed with numerous cracks, holes and missing lugs "repaired" or "replaced" - both those terms are used in their loosest sense and the terms describing quality such as "well done", "professional" and "of a high standard" are most certainly not applicable here!   For example, the timing side main bearing housing is cracked, the lugs that stop the timing side main bearing rotating are missing, great lumps of casting are missing (e.g. round the inlet cam follower), the oil pump mounting surface does a very passable impression of the surface of the moon and many other woes too numerous  to mention.

So it looks like I need to start the re-build (of the engine) from the ground up with some replacement castings and work my way up from there!   

The ONLY good thing that THE previous owner (and I have no idea which one or who they were) that was responsible for such bodgery did was not to scrap the whole thing.     Hmmmmm, I wonder if they are on here and if so, is this an appropriate emoji for them?  :-[ 

Anyway, I think it's a most attractive little bike and was such fun to ride when it was working so I need to stick with it.   I think it could be a long time before it's done  :'(



#22
Singles / Re: BSA Part Numbering
18 November, 2021, 19:47:26
Quote from: idie on 18 November, 2021, 18:02:19
I would try a pair of B31/33 cams as a starting point. You have one already.

Thanks, sounds like a plan  :)
#23
Singles / Re: BSA Part Numbering
18 November, 2021, 16:29:12
You may very well be correct! 

Unfortunately what was to hand didn't seem to be in very good condition as it looks like lobe on the inlet has been "restored" (I use the term very loosely you understand!) by welding and grinding.   Well, nice try but no Cigar ....

My question is aimed at understanding  the differences/similarities in the part numbers so when I plump for replacements from a well known internet auction site it can be done with a modicum of knowledge of what is sensible and/or viable.   I certainly don't need or want "hot cams" for the ultimate in performance, I just want it to run well and run reliably (something hitherto sadly lacking)

Alan
#24
Singles / BSA Part Numbering
17 November, 2021, 20:07:36
I've recently had the need to remove the cams from my B21 single which should both be the same part number.

What I've found is that the inlet cam is numbered "65-2438"  and the exhaust cam number is of a very different form, specifically "A2-1".

The inlet cam is definitely the wrong part number for the bike (from a Gold Star I believe) but my question is is the "A2-1" number a later BSA equivalent number or is it an aftermarket part number?     Is there a conversion chart / table that shows the equivalents?

Any advice gratefully received!

A rather confused Alan
#25
The Star and Garter / Re: Mileage checks
23 April, 2021, 22:54:12
The Odemeters/Tripmeters are operated by pawls with a sharp point engaging in the  fine teeth of the "gear" (not really a gear as it doesn't mesh with another one) on the end of the odemeter drum.    The pawl levers are driven by an eccentric bush that rotates driven ultimately by the input cable.    When the point wears on the pawl it will sometimes fail to advance the drum causing it to record a lower mileage than actually covered.   When the pawl is worn completely it fails to drive the drum at all and the Odemeter and/or Trip stop working completely.    The picture shows a replacement lever I made and fitted to a friends Chronometric to replace the worn original.  The video shows the drive mechanism in operation.

https://www.youtube.com/watch?v=_U2Hb9GrtdU

HTH.

 
#26
Quote from: Editor on 08 April, 2021, 17:41:23
Now there's a thought. Run them down an old speedo outer cable. The purists would never suspect a thing.

As my B21 has no ability to drive a proper Chrono I designed and built an electronic one, driven by magnets embedded in the front hub.   The wires run through a dummy speedo cable and pretend gearbox.   I just hope a future rivet counting owner doesn't try to lubricate the gear box!  ;D

The dummy odometer and trips don't work so the pointer "spells out" the current odometer reading briefly every time you turn it on before going into "speedo" mode.    It was fun developing it but a right PITA to get it working reliably in close proximity to Mr Lucas's finest magneto!
#27
The Star and Garter / Re: Soldering flux
02 April, 2021, 14:17:11
You are much better off when soldering (electrical) wires together using proper multi-core solder and, if you are doing it correctly, you should not need any additional flux.   You can still buy (if you haven't already got any) standard 60/40 lead/tin multicore solder for repair work on old equipment (pretty sure BSA's fall into that category) even though it's use is not allowed for most modern applications.     I think it safe to say that the amount you will use on a lifetime of old bikes will not seriously overwhelm the planet and cause an additional environmental disaster.

Alan
#28
Sorry I don't have any photographs of the appropriate dynamo but can't you just work it out from the direction of rotation of the crankshaft and the number of gears in the gear train to the dynamo?

#30
The Star and Garter / Re: Electric heaters
15 February, 2021, 23:12:16
Quote from: MITCHELL on 15 February, 2021, 19:48:20
Dehumidifier?

Would be a good plan .....