Quite some time ago we were talking about fitting a magneto to a set of cases with flogged out dowel holes.
I mentioned the local chap Peter Scott made up 1/2 moon ones to overcome this but my descriptions were not particularly good.
Well the Maggy had to come off so a chance to take a few pickies.
These cases were fairly good but the ones it is going on are really badly flogged out but it got too dark to photograph them.

email (option): bsansw1@tpg.com.au

Nicely done... better than original round pins in my opinion. Thank you for sharing this.

email (option): teladelujo@msn.com

A lot easier than trying to bodge up a set of cases
The ones this went on to had a repair to the rear strap and it looks like the bike was ridden for quite some time with a broken magneto starp.
Even the slots nearest the timing case were flogged as was the hole in the timing chest.
But the new pins held it nicely in line.

email (option): bsansw1@tpg.com.au

Great idea Trevor for a worn set of crankcases, but how do you think they were machined. With a whitworth thread you would never get them to line up due to the coarseness of the thread. Do you think they were machined with a full head then fitted to the magneto then the sides were machined after?

Tim W

email (option): t.j.walker@btinternet.com

My first thought as well...Perhaps they were aligned with Loctite already applied to the threads and then left to 'go off'....Ian

email (option): ian@wright52.plus.com

They are WW machine screws or set screws ( full thread on shank )
The head is milled flat on one side then inverted and milled flat on the other.
Some with a good hand could file them flat & parallel, but not me.
Then the remaining rectangle of head is ground to the 1/2 moon shape
The 1/2 moon is about 2/3 the depth of the milling in the crank case to allow them to be rotated so they line up.
So none of them were done up tight against the body in the first photo.
No my idea so no credit due.
They were done by Peter Scott Motorcycles a local magneto / dynamo workshop.

In the last photo up can see the edges of the thread machines slightly and in the shot above the pin siting on the bottom of the slot showing that the pin is shallower than the slot to allow for alignment.

Worth the effort no matter what the state of you cases is.
It was a long time ago we were talking about these pins & I thought I had some spares but they had been given to another M20 rider some time ago.

At a guess, considering that they are all within 1/12 of a turn on being fully home the bolts were most likely screwed home then the edged scribed onto the heads then removed and milled down to the mark.

The faithful M 20 is currently off the road as it did a head gasket in 2016 and when it was replaced the piston was sitting lop sided as the gudgeon pin retainer had come loose & the pin made a nice deep grove completely through the std bore liner ( bugger)
That would have happened around 2005 because it was around then it started to blow excessive oil out of the breather when pushed really hard.
Not the fasted machine BSA ever built but these old warhorses are tough and just about unstoppable ( if you have enough oil ) so the War Office did well to settle for them.

The spare engine is just about in so I will be pulling the old one down.
Got an M21 crank to go in and a 1800cc VW piston to sit on top but that is for after the international.

email (option): bsansw1@tpg.com.au