The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: bsarider on 24.03. 2010 11:01
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Would someone have a look at the points off my mag as I explained earlier in the manual it says"move the spring arm off the moving contact breaker point noting that a small but vital insulating washer is interposed between the end of the pivot and the spring arm" I seem to have a half round solder bullet under the spring arm. Your comments would be appreciated. Alan
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G`day Alan, I think I am right in saying that it doesn`t really need to be insulated, the earth is through the outer spring, so it is another earth path. I guess an insulated washer would be kinder to the spring clip.
regards Jim
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jimmy is right. The orange arrows in the retouched pic shows what must be isolated.
Seems the point surfaces show much wear\ burn ?
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Thanks for your comments,further to my posting I have now taken the timing side engine cover off and removed the fiber Wheel which is intact.It wouldnt come out of its
orifice unless I partially drew the magneto backwards off its mounting bolts so thats what i have done.
On cleaning up the magneto I put it in the vice and ran it up with my electric drill in reverse and after about 100 or 200 rpm the magneto stopped sparking from the HT leads.I think I have a faulty magneto that may also have slipped its timing. No horseshoe washer was present under the pinion fixing bolt head which also have added to the slipped timing problem. Alan
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Easy, 'rider; let's not be jacking the mag around.
Firstly, note that the mag driving pinion is self-extracting and can be dismounted from the mag shaft by simply unscrewing the shaft nut all the way. You shouldn't have to remove the mag to do this. See BSA Service Sheet No.203.
Secondly, be careful when you drive the mag shaft to check spark. The safety gap screws must be in place and the spark(ing) plugs should be grounded to the mag body before you go spinning the shaft. Otherwise, you run the risk of blowing the secondary windings in the armature.
Thirdly, if the contact breaker points are burnt you probably have a shorted capacitor ("condenser") in the primary. This is located in the armature in a very inaccessible place. Armature repairs are best left to your Lucas mag specialist.
The mag doesn't "slip(ed) its timing" when it's removed from the engine; its internal circuitry ensure that it's timed to itself. Your task is to time it to the engine. The "horseshoe washer" can fall away when the mag shaft nut is unscrewed: if you don't find it on the shop floor, make a replacement using a one inch OD 1/16th inch thick steel flat washer.
You will save countless hours of frustration attempting to time the mag if you attach the mag driving pinion using a medium strength Loctite to the (clean, dry) taper surfaces after setting the pinion. Remember to wedge the advance if you have the auto mechanism. Tap the pinion onto the shaft gently and let the assembly set for a few hours before you drive the nut on fully.
The K2F is a fine magneto; don't screw it up.
Good luck,
David
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Thanks for your reply David,the mag was driven around with the spark plugs earthed to the body. When I unscrewed the fiber drive it released from the mag taper shaft but would not come out of the inner timing case housing which I had left in place,It was loose from the mag but would not come out .The bike is an A7 longstroke so it could be different to later models? So the easiest way was to draw the mag partly off its mounting studs which allowed me to tilt the fibe drive enought to remove it physically from the bike.The mag is going to Sheffield today for testing and /or repair. Alan
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Well, I did it again: I failed to inquire as to the year and model before composing a reply. Oh, well.
Good luck, Alan.
David
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Just an update on the Magneto,took it to FTW in Sheffield and he confirmed the mag had shorted and the capacitor was also u/s.He says the mag had all its 1949 markings still inside within the mag so he would assume it had never been touched until now.
Alan
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but would not come out of the inner timing case housing which I had left in place
Yes Alan... I do recall that now being a problem on my 1949 A7... and I cant remember now if I had to do as you did, by removing the magneto after the manual advance/retard unit was released from its taper, OR, if I removed the inner cover... OR, jiggled around until I did eventually find away to remove it, bit like a Chinese puzzle.
David... You will save countless hours of frustration attempting to time the mag if you attach the mag driving pinion using a medium strength Loctite to the (clean, dry) taper surfaces after setting the pinion.
That's a good tip to remember for the future... Thanks!