Play in timing advance sprocket

1down5up

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Oct 17, 2014
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Hi all. Going through the process of timing my Atlas.
I have notices there is a reasonable Bounty of play/wobble in the automatic timing advance shafting sprocket.

Is this right? Doesn't seem to be but figure I should check before everything starts summing apart.

This is the shaft that goes In to the magneto.
 
I interpret what you wrote as "play in the sprocket" when the AAU is otherwise solidly attached to the magneto taper. If so, that is not normal.

Can you be more specific?

Slick
 
Play is in all directions and appears to be the shaft itself running into the magneto,
 
1down5up said:
Play is in all directions and appears to be the shaft itself running into the magneto,
Click to expand...

That sounds like bad bearing in magneto. With a bad bearing, the oil seal on the shaft should also be in failure ... do you have any oil in the contact breaker cavity?

The AAU is held to the magneto shaft by a taper fit. There cannot be any play possible between the AAU and the shaft if the center bolt is tight. Thus whatever play you feel must be in the shaft. If in doubt, pull the AAU and test the shaft separately. The center bolt is a self extracting screw .... if it works as it should, the AAU will pop off the taper.

I do not recommend a DIY to rebuild mag. PM me if you want a reference for a professional rebuilder.

Slick
 
It very well could be the bearing itself, however I suggest you remove and strip the magneto and see if the rear bearing is OK as the outer bearing cup is held in place, along with the oil seal by a flimsy paper type component that holds the cup in the rear of the body – these should not be replaced with anything else.
Be careful in dismantling in case any ¼ type magneto shims fall out when you have removed the front points /magneto cover-these should be put back in exactly the same place.
If you have oil in the armature/points the seal will need replacing also.
P.S.
ALWAYS check the points timing on BOTH cylinders with a degree disc ( as well as checking that both points open the exact same amount.)

http://www.britbike.com/forums/ubbthrea ... Post458761
 
Cheers for the help/info. Will look into this this weekend and report back for anyone else that has the same issue in the future
 
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