Discussion in 'Norton Commando Motorcycles (Classic)' started by WEM, Apr 1, 2019.
I'm just wondering if it's possible to replace the springs on the AAU without removing the AAU.
Really need to inspect the slots and pegs, file off burrs, etc when dealing with these. If sticking, chances are it is not the springs.
They don't appear to be sticking but one weight seems to be almost flopping loosely back and forth. As far as I can see, the spring on that weight looks to be in place but I can't really get a look at the end of the spring. If it's possible, I was hoping to be able to replace the spring on the loose weight without removing the unit.
I would replace both springs with new.
Removing the AAU does not offer any advantage to replacing the springs other than the convenience of having the AAU in your hands, rather than dealing with it on the bike.
I don't know enough to know if what I've done is an issue or not but I'd appreciate any feedback folks want to offer. It may be a non-issue. You'll have to excuse my ignorance. I pulled the points plate off to have another look at the auto advance unit. I marked the location of the points plate relative to the case first so I could put the points plate assembly back in the same location. As a reference, I also had the timing slot on the end of the AAU lined up with the plastic heel of the right (drive side) contact. This opens that set of contacts. I turned the AAU by hand to see if the AAU springs were working and they seemed OK after lubrication. However, I also turned the cam shaft by using the kick start to see how the AAU would behave. Unfortunately, I didn't think to keep track of the timing slot on the end of the AAU when I turned the camshaft. I lined up the points plate with the marks I had made when putting things back together. And I lined up the slot in the end of the AAU with the heel of of the drive side contact. But, and this is my issue, I don't know if the camshaft went around 360 degrees when I was turned the cam shaft by using the kick start. So my question is, even though the slot in the end of the AAU has been realigned with the plastic heel of the drive side contact, is it an issue if if I didn't rotate the cam shaft a full 360 when I was turning it via the kick start. Like I said, unfortunately, I don't know enough to know if this is an issue or not.
If the complete AAU hasn't been put back in exactly the same position in the camshaft taper then the ignition timing will be out so the timing needs to be checked.
If you only removed the AAU cam without completely removing the AAU then you need to ensure the cam goes back on the AAU body in the same position it was before and not 180 degrees out.
LAB, Thanks for the quick reply. Sorry if I wasn't clear, but I didn't remove the AAU or the AAU cam at all. I just pulled the points plate off and lightly lubed the AAU mechanism which seems to have fixed the bob weight/spring issue I was having. If I didn't remove the AAU, I'm thinking now after some thought that rotating the cam shaft via the kick start would not cause a timing issue as everything would still be in the same relative position?
Yes, as long as the tapered fit between the AAU and the camshaft was not disturbed, the AAU cam is in the same position on the AAU body and the points back plate refitted in the same place then the timing should not have changed.
That's great to hear. Thanks. I really appreciate the advice.
LAB, just a few quick follow-up questions to your earlier reply:
1. How do I remove the AAU cam without removing the complete AAU?
2. If just the AAU cam is removed, can the bobweight springs be replaced then without removing the complete AAU?
3. Is there a dowel on the cam shaft with a corresponding slot on the AAU for alignment purposes like on the Triumph AAU's?
If the springs are unhooked from the spring posts (and with the AAU retaining bolt removed) the cam will pull off the AAU spindle.
Thanks. Really useful information.
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