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Adjustable mag sprocket

Posted: Thu May 17, 2018 5:53 am
by wade.edwards
I've done plenty of searching here and the great w.w.w. without finding out what happened to Serco's adjustable mag sprockets. Serco appears to no longer be in production and may or may not have morphed into another company but they are not listing said sprockets.
Would appreciate an update if anyone is in the know. Thanks

Re: Adjustable mag sprocket

Posted: Thu May 17, 2018 6:21 am
by nevhunter
I can't help you there Wade. IF you have an original puller, I find it's easy to use the camshaft sprocket to make small adjustments, rather than the magneto shaft. Vintage AJS 's used a telephone dial and pin style vernier adjustment which I think the one you mention is similar to.. Nev

Re: Adjustable mag sprocket

Posted: Thu May 17, 2018 10:05 am
by david.anderson
Wade
I believe this link is what you are after. http://www.mdamotorcycleengineering.com.au/index.html
David

Re: Adjustable mag sprocket

Posted: Thu May 17, 2018 7:51 pm
by wade.edwards
Thanks for the suggestion, Nev. Although an unconventional idea, others have tried this method successfully.
David, you have your finger on the pulse. Thank you for the link. At least one company is full service. Amazing.

Re: Adjustable mag sprocket

Posted: Fri May 18, 2018 5:11 am
by Ian.Taylor
I noticed these Sprockets do not have the thread Boss for the puller.
My 31 Norton has No such boss and when you try to remove the sprocket , I get worried that I may break a case trying to get the sprocket off. Lever s behind the sprocket and try to tap the mag shaft is not my idea of fun.
I haven't tried the cam shaft sprocket yet , I may next time on my Ariels.

Re: Adjustable mag sprocket

Posted: Sat May 19, 2018 11:29 am
by iansoady
I've seen a picture of a tool for removing Norton mag sprockets that consisted of a lever bent into a U shape so that the short end of the U slips behind the sprocket and the longer end bears on the end of the spindle (with nut on a few threads). A sharp tap on this longer end then bounces the sprocket off (allegedly).

I'll see if I can find that picture.

Found it:

Image

Re: Adjustable mag sprocket

Posted: Sun May 20, 2018 1:28 am
by nevhunter
The Lucas Magdyno has only 2 screws holding the brass slip ring end on to the coil body of the armature and it's a long way from the ballbearing that supports the shaft to the threaded end. Prising and belting the end is not on. Runout of the shaftmakes chain adjustment impossible and may cause armature runout and polling on the case and loose or tight chain on an Ariel (or JAP ) will damage things. You need that puller tool. Also have the thread on the shaft undamaged (3/8 BSF). You have no good way to stop the shaft turning when you tighten the nut before the Taper binds so both the nut and the shaft thread must be in good condition, as well as the tapers. Best time to check all this is when it's on the bench before you put it on the bike.. You could make a puller for the After market sprocket. It could operate on the 3 screws quite satisfactorily. Just replace them with longer ones and have them through a thick washer that impinges on the shaft end , has 3 appropriate holes and tighten the screws evenly and you have the puller . Nev

Re: Adjustable mag sprocket

Posted: Sun May 20, 2018 7:42 am
by john.whiting
My take on this is that if one of the fixing screws falls out ,its a good chance of getting jammed in the chain and breaking the mag shaft out of the armature.......if you are lucky...As for the Norton tool,I made a similar device (with a puller screw) from an old shifter .....just to get some good steel ,and it works OK.......but it would have been a lot better if Norton had used a threaded boss for a puller ,like Ariel......In fact Ariel was the only maker to provide this very helpful feature........and there is no reason that Ariel sprockets cant be used on a Norton.

Re: Adjustable mag sprocket

Posted: Sun May 20, 2018 5:32 pm
by cmfalco
john.whiting wrote:My take on this is that if one of the fixing screws falls out ,its a good chance of getting jammed in the chain and breaking the mag shaft out of the armature.
This is no different than many other places on our motorcycles where if a screw falls out bad things would happen. That's why we use Loctite and torque wrenches.
john.whiting wrote: there is no reason that Ariel sprockets cant be used on a Norton.
Other than the fact Nortons don't use 12T sprockets.

Re: Adjustable mag sprocket

Posted: Mon May 21, 2018 3:15 am
by john.whiting
Lots of owners use Matchless sprockets on Nortons,a wider ,finer pitch chain,gets away from the bicycle chain.If the sprockets are the same number of teeth and fit in the case,IMHO,the chain line will be right.All British bikes used the old Bosch large taper as a standard.Even BSA A7/10 generators use the Bosch taper ...and so would Ariel 650s