Re: Magneto direction
Posted: Tue Mar 13, 2018 8:24 am
You are.
R = clockwise from the DRIVE end, and L anti-clock from the DRIVE end - so it's as you say at cb side. Not all plates are marked though.
You can almost always re-notch, using a dremel or similar, to convert. Sometimes things get tight due to presence of other notches that you 'run into' but usually not.
Key thing is not to make a mistake in the position as that can cause problems!!
To help in not screwing up here, it is a very good idea to extract the eccentric limit-stop screw that is under a little pimple on the cb end housing. Find a standard 1/4BSF screw, and use it as a grub screw to lock the camplate into what you think is the best position for the opposite rotation. Then run the mag as fast as you can. The reason I say this is that you can often get excellent low speed sparks, but they disappear at high revs if the internal timing is over-advanced, because the magnetic flux 'bends' in the direction of rotation with speed. If the points open even a hint of a fraction before the 'right' moment, the spark will be lost. Better to be a tiny tad retarded internally than too advanced. Remember also that each thou extra on the points gap creates another degree or more of 'advance', and vice-versa as the gap is reduced.
Having got the advanced position right using a 12 thou gap, then grind the notch to give the required retard. About 10mm or 11mm wide is right for about 20-22° of movement, which is quite plenty. The eccenric pin, when refitted, gives you some adjustment for fine tuning.
Be just as careful with the AR cable notch. An error there, and the thing will drop out or pull out of engagement and that is a pain in the proverbial.
Note that camplates come in two or more thicknesses, and I don't know where you get new ones these days, hence preference for modifying. Too thin needs a spacer behind - fiddly - and too thick won't allow the circlip to fit . . . Wobble due to being too thin is bad as it can affect the points gap with the face cam - so things need to fit properly.
Good luck!
R = clockwise from the DRIVE end, and L anti-clock from the DRIVE end - so it's as you say at cb side. Not all plates are marked though.
You can almost always re-notch, using a dremel or similar, to convert. Sometimes things get tight due to presence of other notches that you 'run into' but usually not.
Key thing is not to make a mistake in the position as that can cause problems!!
To help in not screwing up here, it is a very good idea to extract the eccentric limit-stop screw that is under a little pimple on the cb end housing. Find a standard 1/4BSF screw, and use it as a grub screw to lock the camplate into what you think is the best position for the opposite rotation. Then run the mag as fast as you can. The reason I say this is that you can often get excellent low speed sparks, but they disappear at high revs if the internal timing is over-advanced, because the magnetic flux 'bends' in the direction of rotation with speed. If the points open even a hint of a fraction before the 'right' moment, the spark will be lost. Better to be a tiny tad retarded internally than too advanced. Remember also that each thou extra on the points gap creates another degree or more of 'advance', and vice-versa as the gap is reduced.
Having got the advanced position right using a 12 thou gap, then grind the notch to give the required retard. About 10mm or 11mm wide is right for about 20-22° of movement, which is quite plenty. The eccenric pin, when refitted, gives you some adjustment for fine tuning.
Be just as careful with the AR cable notch. An error there, and the thing will drop out or pull out of engagement and that is a pain in the proverbial.
Note that camplates come in two or more thicknesses, and I don't know where you get new ones these days, hence preference for modifying. Too thin needs a spacer behind - fiddly - and too thick won't allow the circlip to fit . . . Wobble due to being too thin is bad as it can affect the points gap with the face cam - so things need to fit properly.
Good luck!