Aplogies that I am a bit late with this image. (There is a rubber cover yet to be fitted over the switch mechanism.)

The gearchange quadrant shaft has suffered during the years this bike was stored in tea chests.  I was going to ignore it, as I reasoned it was cosmetic and the shaft is invisible. But I notice Draganfly do a shaft repair service. There is no oilseal on the gearchange shaft. Is there a reason why it would be worth getting a new shaft fitted? 

I have contacted RTS, as I now realise that the inner camshaft bush is excessively worn, the outer is worn and loose, the end float is excessive and my NOS inner bush will certainly need line reaming as the camshaft won't go in at all. 
Just in case they are booked up - are there any other respected BSA engineers about? Ideally somewhere in Yorkshire! 

Thank you!

I've rewritten this to remove verbiage.

On a C15F, does the inner camshaft bush fit into a rebate such that the outer face is flush with the surrounding aluminium? Or in my case, slightly recessed?

Or to put it another way - is the inner camshaft bush in the picture positioned exactly as it should be?

Thanks so much for the chart. I will do some measuring and see if my new bush needs reducing a fraction before I go in for round two. 

The same thought had occurred to me - how could the outside diameter of the bush be worn when it is pegged. I went to my favourite US website that give pictures and dimensions for nearly all C15 parts (bsaunitsingles.com) and it informed me that the bush outer diameter should be 0.9155". My bush measures 0.9075" - so I think it has been an undersized pattern part. 
The new bush I have obtained measures 0.9165" - and it certainly is not a push fit in the case.I tried tapping it in after having the bush in the freezer for a couple of hours and heating the case for a few minutes with a hot air gun, and it wasn't having it. So today's question is how much interference should a bush like this have?

I found there seemed to be considerable camshaft end float when checking as per Rupert's book. I then discovered that the outer camshaft bush was loose in the inner cover, which appears to be due the outer dimension of the bush being considerably less (0.9075") than the correct 0.9155". So with a new bush obtained I went back for another look, and was musing on what the camshaft actually bears against end to end. And it didn't really seem right at the crankcase end. (See picture.)
Having now seen photos of the inner camshaft bearing, it appears the entire lip has disappeared!

Unless - does the bush lip fit into a recess? So it is supposed to be flush?
Or has it been installed backwards (with the lip in the crankcase)?

There is some evidence of the side of the cam lobe scuffing the crankcase above the bearing.

My BSA A50 (blue) has what I believe is the standard bars - 68-4971.  I recently saw a similar bike (red) sold on eBay. The red bike has bars with slightly more raise than mine. Does anyone have any clues what the bars on the red bike are. (I don't think they will be the BSA USA bars which appear higher.) I fancy trying them on mine. Any clues on who might stock them would be massively appreciated!

The outer camshaft bush is slightly loose in the case on my C15F project. This only came to light when I was checking the camshaft endfloat. I can pop it out of the case with a tiny bit of finger effort. It is a nice fit on the camshaft - and it is pegged (so it hasn't been rotating).

Obviously I could find and fit a new bush, and ream it as required. But could I alternatively use some loctite bearing fit or similar to secure it? Any downsides?

I managed to get the C15F sludge trap out today. It is packed with crud.

My question is - is it safe and logical to clean this detritus out with the crankshaft assembled? It seems to me that there is danger of me loosening rubbish that could drop into the oilway to the big end.  On the other hand, given that the big end has no play (and may be new), is separating the flywheels solely to guard against this likely to do more harm than good?   

Piccies attached

There is one on my A50 - and I have never oiled the chain in 27 years of owning and riding it - on the same chain and sprockets. Yes, it does deposit the odd drip of oil from that area when parked - which reassures me everything is as it should be!  But I take Rupert's point - I will try the C15 one (when the project is complete) and see if the supply is as finely judged as my A50 chain oiler. 

Rats.  I found a dealer with some in stock, so ordered a couple... from America..  The ratio of item cost to postage cost was distinctly unfavourable!

Hi Rupert

My brother says he has one that matches your requirements. Pictures attached.

Is that any use to you? 

I'm reasonably certain he would sell it.

Cheers