Hi all, having recently installed a Trispark, I have my 15 year old digital boyer just sitting around.

A friend just bought a 1970 era BSA 650 Lightning and would like to dump the stock points set up.

Can we mount my Boyer?

If so, anyone know how many degrees BTDC to strobe it at, and at what rpm for full advance.

Or since the Boyer is supposedly fully advanced at 5000rpm, from memory, just be ok to set the timing at whatever degree BTDC at 5000rpm?

We don't have our hands on a workshop manual yet, so don't know what the timing calls for.
Thanks for any comments
John

Yes, it's the same thing, even the rotation.

It may work , If you don't mind an initial advance of around 15° ..

Ludwig, there's a different advance between the BSA & Norton ignition boxes?

grandpaul wrote:Ludwig, there's a different advance between the BSA & Norton ignition boxes?

I don't know , but I do know the analogue boyer for a Commando has a rather flat advance curve : about 10 - 12 camshaft degrees , = 20 - 24 crankshaft °.
The Norton engine needs only 29-31° total advance , thanks to the exellent design of the cylinder head . Most comparable engines need much more advance .
The BSA must be , IIRC , around 35 -36 ° .
This means that advance at kickstart or idle rpm is around 10° for a Norton and 15° for the BSA , using the same box .
Ideally , it should be closer to 0° .
That's why many change to Pazon or Trispark , who have steeper advance curves .

I have done this very thing over ten times with good results.
Simple to use the timing lock tool for BSA to check that the mark on the rotor is still good about 34 BTDC than static time the Boyer. Always strobe light it when it runs using the primary side rotor mark to be sure it's right. Read the back of the Boyer plate before installing it and mark the anti clockwise hole with a felt pen so you know you’re on the right hole. Seems a bunch of us have both bikes and ride them hard. BSA's love to rev they have a better rod ratio than a Norton in stock form. The Norton will out torque a BSA from down low but a BSA will run away once the motor has some revs. The Boyer will help with the pinging VS points with its slower advance. The Boyer curve is suited well to A-65's for this reason. If the Boyer starts a bit high it’s not too much an issue as long as it lands on the mark at full advance. A Pazon doesn’t hurt a BSA (I have used them)but they are good for using old Boyer Mark 4’s up.

Micro Digital has a steeper curve with a kink at the start to stabilise the tick over, so may not be a pink free as the analogue but worth a try. Have one on a B44 and it did reduce the pinking over the AAU.