Bean can

[Dizerens5]

Early (1979...) R65s used contact breaker ignition and the ATU cannot be removed from the bean can (at least, not without an unusual tool) and anyway neither the ATU nor its parts have ever been available as spares. Anyone know why BMW did this? It seems a very unusual and unnecessary restriction. A failure in the ATD means buying a whole new bean can, very big money and no longer available in this country anyway it seems.

[Bob_Roller]

I don't know about the contact breaker points type 'bean can', but it doesn't look much different from the electronic version.

I think the clue, is it has to be disassembled from the bottom .

The drive plate at the end is held in with a roll pin and I think there is some sort of spiral wire snap ring or circlip that prevents the pin from moving, once that pin is removed, it comes apart quite readily .

But you are right, that parts are not available from BMW .

I think Motobins in the UK has the centrifugal advance mechanism for sale without purchasing the entire  'bean can' .

http://www.motobins.co.uk/bmw-parts.php?model=R%20Series%202%20valve%20Twin

Part number 72660 .

I was almost right, looks like nothing available for '78 or later points, these parts may work, they just don't say they are effective for them .

[Barry]

Early (1979...) R65s used contact breaker ignition and the ATU cannot be removed from the bean can (at least, not without an unusual tool)  

Well it's certainly not easy and I suspect from what others have said in the past very much more difficult than the later bean cans. If I remember correctly there are 2 securing screws but the real problem is that the bean can has been crimped to lock the points baseplate in place. What I did was to improvise a pin wrench type tool ( couple of steel bars set at the the correct spacing in an engineers bench vice) to rotate the base plate until the crimped areas were no longer holding the plate.  It was a real struggle and before reassembly I carefully relieved the edges of the base plate to make it something less of an interference fit not too much though as it's important that the base plate is secure and remains concentric with the points cam to keep the timing equal on both cylinders.

Best of luck if yours is as tight as mine was it's a swine of a job. BMW went way overboard with the crimping.