I thought the soap trick was for annealing aluminium (that's certainly what I use it for and it works a treat!), "soap" blacking temp wouldn't have been high enough for annealing copper I would have thought. 

As others have said, cherry red (in subdued light).

Alan

Quote from: AdrianS on 17 November, 2020, 16:45:40
Riding my old BSAs is a part of a calorie controlled diet. I usually end up having to push them home!

I know I did a few weeks ago.    A mile and a half (even if half of it was downhill) was a long way and it was only a little old B21 250!

Alan

Well at least you're in with a chance, it still exists and is currently taxed!

Alan

Many thanks Dave for the advice.

I'll give it a go if I can track down some replacement studs, I suppose I could have a crack at making them if not.

Alan

The threads on the crankcase studs that hold the pushrod tunnel and the oil filter gauze/sump plate in position are quite badly worn on my little B21 and I'd like to replace them if possible.

Simple question; do they just unscrew from the crankcase with the aid of suitably applied torque using for example a pair of Molegrips or is there more to it?   

Thanks

Alan

Quote from: Gtt on 14 September, 2020, 12:44:15
I would think an oversize gudgeon bush could be made to accomodate a standard gudgeon.

Too late for that ......

After my tail of woe regarding the piston and ring failure on my little B21 (See the Pre-war thread if interested) I want (no, need) to flush out the crankcase to make sure no debris remains - I DO NOT WANT TO BREAK THE BOTTOM END DOWN AT THIS POINT (which ultimately would be the ideal thing to do I suppose but it's not happening at the moment!).   

So, to aid me in this task I have a couple of questions if I may?

1) Can the oil pump be removed and put back easily from the engine with it in the frame and, perhaps more importantly, what points do I need to look out for e.g. shaft, gear or whatever alignment, gaskets, bolts to remove or not remove etc etc?

2) I think (if my understanding of the Parts Book is correct) that in my engine the timing shaft/wheels/cams etc have a retaining/bearing plate underneath the outside case so can I just remove the timing side outside crankcase cover to clean/make sure no debris is lurking there whilst leaving the valve timing etc intact?

With the oil pump removed for separate cleaning, my plan is to flush the crankcase through with paraffin or similar and dry/clean out with compressed air to ensure any debris is released and expelled.    Similarly, with the timing side cover removed that area will be similarly treated.

TIA

Alan

Well I both calculated and measured the compression ratio to be around 10.5:1 which is something over the stock 6.2:1!    No wonder it was sprightly when running but was obviously seriously over-cooked.   Fortunately it now appears the piston and rings bore the brunt of the abuse.     

As the conrod little end is now sized for the the Triumph piston and not the BSA there's no easy way back to stock.  So, I've got a replacement Les Harris Triumph piston at +040 (well, to be correct I've actually got two as they come as a pair for the twin  ), the barrel is away being re-bored and the plan is to insert a 2mm annular copper head gasket between the liner and the head and provide a slightly thicker version of the aluminium base washer/spacer that was fitted when I got the bike.   The intention being to get the CR down to around 8:1 which hopefully will be a lot kinder on the old girl but still retain a little bit of the "High compression" sparkle that I was just getting used to.   I'm just hoping there's enough "capacity" in the tappets to accommodate the increased distance between the followers and the rockers.    Fingers crossed!

Anyway, we'll have to see how it goes.

Alan

This is how "snug" the nose of the saddle is to the tank on mine,  I suppose a longer, two spring sets one would fit as well?

You really need to track down a known Terry saddle of the period I suppose to be sure, even a catalogue wouldn't necessarily answer the question unless it was extremely detailed.   Imagine uncovering an original drawing of the S782!   If you did, I'd rush out and buy some lottery tickets while your luck holds!

Alan

Here are a couple of photographs of my saddle.   I have no idea if it is the original or even made by Terry.  There is no manufacturers label on it although the cover material does appear to be lined with wool and fairly old (but 81 years old? )

One thing is for certain, not all the springs are original, a right motley bunch if ever there was one!

One point of note is that all of the saddle photographs I managed to find seem to have two sets of springs linked by a plate, my saddle only has one set attached to a pivoting plate at the front which is probably significant but I have no idea what it tells us!   

Sorry I couldn't provide more help!

Alan

According to the spares book the B21 Deluxe had a Terry S782 saddle (although I'm not certain how much help that is!)

Alan

I have a B21 Deluxe, I don't know if the saddle is original or not but I'll take a look and report back.   

Alan

I wouldn't be putting the battery in the airing cupboard,  room temperature storage would be kinder.

Alan

Thanks Julian.

Yikes - That compression ratio isn't very high!

I'll see if I can get that figure with the calculator I'm using, that will give me a good idea if the value I work out for the T100 piston is correct.

Alan

Julian do you have the spec for the B21 Super engine anywhere please (or can you point me in the right direction)?

Particularly useful things to know would be: the standard compression ratio, con rod length,  deck height and really pushing my luck, the head's chamber volume.   

I'm trying to work out what the compression ratio was with the T100 piston so that I can see how much higher it was then it should have been.    I've measured the volume of the head's chamber volume as best as I can by measuring how much fluid it will hold (good job the valves don't leak) but I'm sure there's some measurement error included.

Any info you can provide will be gratefully received!

Alan