The BSA A7-A10 Forum

Technical (topic titles must be descriptive) => Lucas, Ignition, Charging, Electrical => Topic started by: bsaalf on 21.05. 2009 20:54

Title: k2f magneto
Post by: bsaalf on 21.05. 2009 20:54
the magneto on my 1960 a10 is stamped with these numbers k2f  42264d and 563 do anyone know what these numbers mean and do they help with ordering parts if needed in the future !
Title: Re: k2f magneto
Post by: groily on 21.05. 2009 22:00
The important things to know are it's a K2F, and that it rotates anti-clockwise looked at from the drive end. The only other things that matter for support and maintenance are whether it's got an ATD auto-advance/retard unit or a cable and moving cam ring, as there are differences in construction between the two. Cam rings differ between clock and anti-clock rotation.
If you have a K2FC, I think you don't as the 'C' would be in your list of refs, it will have a screw-on end cap at the points end plus HT pick-ups which use 2 screws each to secure them to the body instead of the spring clip on the standard item. Plus a cable for AR. The HT pick-ups and the contact breaker end-housing are not-interchangeable between the 'C' and the others, and there are myriad minor differences between end housings, end caps and their screw fixings, but all the guts are the same across the K2F range: the armatures, bearings, contact breaker backplate and points. Parts can be got from any number of very helpful people, see loads of threads here!
Title: Re: k2f magneto
Post by: bsaalf on 21.05. 2009 22:30
thanks groily very helpful great site cheer's
Title: Re: k2f magneto
Post by: trevinoz on 22.05. 2009 00:18
Alf, according to the Lucas book, your magneto belongs to an A.J.S. or Matchless Twin. It is listed as "Anti-clock Right hand. The Right hand refers to the side of the housing to which the advance cable fits.
The B.S.A. item is part 42263 which is "Anti-clock Left hand".
If you have manual advance and the cable is on the right hand side, you have to pull the lever to advance ignition instead of retard.
The "563" is the date of manufacture.
Title: Re: k2f magneto
Post by: bsaalf on 22.05. 2009 21:31
thanks trev now i am confused because i have just looked at the mag and looking end on from the points end where the kill button is the able comes out on the left side high up, and also i have the lever mounted on the right hand handlebar so which way do i pull to advance it !!
Title: Re: k2f magneto
Post by: a10gf on 22.05. 2009 23:16
Seen from points cover, cable on left side = pulling the cable will retard ignition. To check it: open the points cover and look at the cam ring, find out which way you have to pull or push the lever to move the cam ring clockwise, thus retarding the points opening relative to the piston position (you'll get the spark closer to top dead center or thereabout). I'd imagine the lever on the right side you'd have to push it away from you to retard (I've got it left side, pull retards).

pic here

I Hope this explains some of it.

Title: Re: k2f magneto
Post by: groily on 22.05. 2009 23:20
Alf, if the cable comes into the mag high up on the left, the mag is set up anti-clock with left hand end housing, which is ideal. The cable should be tightened, ie pulled at the lever to pull the cable upwards at the mag, to retard as A10gf says. So with the lever fully relaxed (cable extended) you'll be at full advance. I prefer my ignition levers on the left, but that's just a matter of choice and competition for space on the bars. Whichever side, if the lever on the cable is facing towards the outside of the bars, it's forward for advance.
Funnily enough, re Trevinoz' detective work, on both my AMC twins the mags - which are anti-clock like on our BSAs - have the lh cable fitting same as yours, which is what they ought to have from a practical point of view. Space was tight on AMCs under the carb and inlet manifold, and that's maybe why some mags for their twins had the rh end on an anti-clock job. But basically the rh end is better for a clockwise rotator. Plus the fact that there is no guarantee the plate on the mag describes what it is exactly . . . either because anyone can buy a plate and stick it on, or because the mag has been played with (as most have over the years given that so many parts are interchangeable). I doubt any of my mags are exactly what they say they are on the ticket . . . but they all work just fine.
I think you should check that the cam ring is free to move for its full movement - check by taking the end cover off and watching what happens as you pull and push the lever - and adjust to be sure that the cam ring moves the full breadth of its slot against the peg on the inboard side. Worth checking the ignition timing is correct while you're on, see loads of comments in this here forum. Wonderful devices, and when you've poked and played with it, you'll have no troubles that can't be easily solved thanks to the people who support us with spares.
Title: Re: k2f magneto
Post by: mrshells on 22.05. 2009 23:40
Im not an expert but a K2F with a C ie K2FC is a competion mag with screw on pick ups
it has bigger bearings than a standard mag
a different body
different windings on the armature
a chrome points plate retaining screw
as you said different end plate and screw on cover
Im no expert  but i have a friend whos a proper Mag train spotter
also a k2fc is worth £100 more than a standard K2F *smiley4*
Title: Re: k2f magneto
Post by: bsaalf on 23.05. 2009 00:02
ok thanks everyone i understand it now, i am new to classic motorcycle riding and i am very greatful for all your help what a great forum so much knowledge cheers all..
Title: Re: k2f magneto
Post by: a10gf on 23.05. 2009 00:14
bsaalf, this is one of the main reasons for the forum to exist, and nice to read it's providing help.
Title: Re: k2f magneto
Post by: bsaalf on 23.05. 2009 00:18
spot on a10gf couldn't agree more .
Title: Re: k2f magneto
Post by: groily on 23.05. 2009 07:10
Not going to argue with a train-spotter mag watcher Mr Shells, not at all! Passing observation can't compete with deep-rooted passion!
The bodies are different because the HT pick-up diameters are different and there are the screws, the end cap is very different, no idea about whether there's a shiny screw, and I'm happy to be put straight on the bearing dimension about which you're right. But the armatures? Are they really different? Next time I have the C apart I'll do a proper comparison with the spare standard one on the shelf. Cos I'm going to be a train-spotter too when I'm big.
Whatever, I've got my C on my A as it's my best mag on my trustiest workhorse and although it's a tight fit under a Monobloc and ski slope with the AR cable at the angle and the vertical-pointing HT pick-ups, I'm very happy with it. Whether the thing's really worth 100 quid more than any of the other mags round here is a matter for endless reflection! Maybe I should polish it more to improve that reflection?
I find continually that when you want to buy something it is rare and expensive and involves sucking air through teeth and lots of mumbling about rocking horse droppings and shaking of the cranium, but when you want to sell same, it's common as muck and not desirable . . . . 'twas ever thus!
Title: Re: k2f magneto
Post by: fido on 23.05. 2009 08:18
That explains it  *smile* Back in the '80s when I had my A7SS I had to pull on the advance lever to get full advance. I remember this because it tended to work it's way closed by vibration so sometimes if riding with others I had to hold the advance lever just to keep up! Obviously it should not have worked that way but someone must have fitted a different magneto before I got the bike. The original mag can't have lasted long though as the bike was only used on the road for 9 years before I got it.