Magdyno aaahh!

[Kevin.Priest]

Sorry but I am steaming tonight as I am trying to get the wife’s bike ready for the German rally and again more agro.
I’ve paid a recomended chap to have the mag overhauled apparantly a new armature was required and I’ve now just come to time it up and the taper of the new armature either doesn’t suit the pulley or the taper doesn’t protrude enough . Which ever way it is it ain’t gonna work . Anyone had anything similar , if so did a new sprocket gear help ?
I’ve tried my sprocket on the old armature and it fits nicely .
Getting close to a big sell up as much as I like my oldies i don’t think I can handle the niggling agro anymore .

[nevhunter]

That's a bit sad and really shouldn't happen. If you start swapping bit's from one armature to another you can expect some misalignment but it still might be worth a try Remove the front drive shaft bearing slip ring etc and undo the two long screws and try a swap from another armature. Check alignment (runout) and if you get away with it that's fine. The armature must not pole. Don't machine it as you will have too much pole clearance if you remove much. You might file a few high spots of and get away with it. A lot of electrics people get the "mechanical" aspects wrong. I get the coils done and do the rest myself (Not because I like to) but I have to. Hope you get it OK for the rally..Nev

[john.whiting]

Im a bit surprised that a collector with a number of bikes does'nt have several spare magnetos.......I have many from the old days......when you could argue over a $2 price tag at a swap,and get the price dropped to $1.......At a recent clearing auction sale in Toowoomba ,hundreds of Lucas and BTH mags went in a job lot lot for $500.........but some of the rare stationary engine mags fetched $1000+ each,and there were buyers from the US there......John Deere 2cylinder poppers always bring in wide interest.....and farmer level money.

[paul.wirdnam]

Remove the front drive shaft bearing slip ring etc ...

Nev, you know that is alot easier said than done...without the right tool. How many slip rings have been broken by people not removing the earthing brush, or trying to pull off the drive bearing inner race? It's not an easy task...unless you have an Octopus:

[nevhunter]

Paul about 30 years ago, I set to and machined a cylindrical hollow puller that is slotted and a collar slides up the outer area and stops the bits that fit into the inner race groove from coming out of the groove A 1/2 " bolt pushes against the shaft for the long end and a small mandrel goes in the short end to protect it, It works fine and I have used it literally by now probably 1,000's of times. Don't try to remove the race without something like the proper tool. It's well nigh impossible unless the race is too loose a fit. those armatures are not that robust and easily distort. Runout causes timing chain problems potentially also. In this case the people who did the job should rectify it, one would think. I get lots of magnetos others have worked on. Nev

[john.whiting]

Everyone has a small worn out three jaw lathe chuck from a little lathe........its a very simple job to modify the tips of the jaws to exactly fit the groove in the bearing race..........I might add ,I knew a professional magneto repairer who always removed the bearings with a bit of heavy brazing rod bent into a "U" shape,and clamped in a vice,and I'm talking expensive Bosch and CAV car magneto s,as well as bikes.......no puller,he used to twist the race off with a flick of the wrist.......I prefer to use use my chuck device,and do no damage.

[paul.wirdnam]

Paul about 30 years ago, I set to and machined a cylindrical hollow puller that is slotted and a collar slides up the outer area and stops the bits that fit into the inner race groove from coming out of the groove A 1/2 " bolt pushes against the shaft for the long end and a small mandrel goes in the short end to protect it, It works fine and I have used it literally by now probably 1,000's of times. Don't try to remove the race without something like the proper tool. It's well nigh impossible unless the race is too loose a fit. those armatures are not that robust and easily distort. Runout causes timing chain problems potentially also. In this case the people who did the job should rectify it, one would think. I get lots of magnetos others have worked on. Nev

Nev, several years ago, I also made the same style puller (below) and it works very well. The only downside is that you need an additional one for each bearing size, so I have a much smaller one for pulling off the races on the end of dynamo armatures. John's idea of using a modified 3-jaw chuck is great idea except I can't agree that "Everyone has a small worn out three jaw lathe chuck from a little lathe" lying around .

An Octopus bearing puller sold on eBay back in May of this year and it went for less than £5....lucky buyer as I would have paid a lot more than that.

[Kevin.Priest]

Thanks for replies, not sure about Johns reply though,Austrailia is obviously very different to the uk , I may have some spares but generally don't have loads just lying around my workshop to suit different bikes. Anyway Ive made a decision and have abandoned this for now, we are still gonna go to Germany and the annual but reluctantly on a different make of bike.

[john.whiting]

I was talking to the owner at the Toowoomba clearing sale.....and he said....".One morning I woke up,and decided i didnt want hundreds of tractors any more........I want to do something different,now."

[Kevin.Priest]

I was talking to the owner at the Toowoomba clearing sale.....and he said....".One morning I woke up,and decided i didnt want hundreds of tractors any more........I want to do something different,now."

John You didn’t type this then “Im a bit surprised that a collector with a number of bikes does'nt have several spare magnetos.......”