AAU Fixing Screw m4x10

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tobydmv
Posts: 85
Joined: Wed Apr 16, 2014 4:59 am

AAU Fixing Screw m4x10

Postby tobydmv » Fri May 08, 2020 1:22 pm

Anyone have a pic of the auto advance screw and washer? My screw rotted out a long time ago and was replaced with a socket head allen bolt since that's all the hardware store had. I'm trying to track down the source of some random kick backs that kind of come and go as they please. I'm wondering if the AAU might be getting stuck in full advance due to the allen bolt i'm using or maybe the springs arent retracting it, IDK at this point. If you have any other ideas please let me know. It seems to be really bad some days and other days not at all. I probably need to reset the timing again.

Duccout
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Joined: Wed Feb 05, 2020 1:20 pm
Location: Essex UK

Re: AAU Fixing Screw m4x10

Postby Duccout » Fri May 08, 2020 2:28 pm

I'm not sure that can happen - the AAU cam on mine has a lot of end float and would not be gripped by a washer. These parts are now so old that I would guess that most AAU are really worn.

tobydmv
Posts: 85
Joined: Wed Apr 16, 2014 4:59 am

Re: AAU Fixing Screw m4x10

Postby tobydmv » Fri May 08, 2020 2:35 pm

Duccout wrote:I'm not sure that can happen - the AAU cam on mine has a lot of end float and would not be gripped by a washer. These parts are now so old that I would guess that most AAU are really worn.


Yeah I agree, I just took a really close look at the old AAU and the cam lobe is recessed from the advance shaft. I dont think the fixing bolt or washer can capture it unless the washer is conical and mine isnt. My AAU also seems to be free to advance so i'll check the timing again and go from there.

ducwiz
Posts: 515
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: AAU Fixing Screw m4x10

Postby ducwiz » Fri May 08, 2020 5:43 pm

Have you looked into a parts catalog, especially for your bike? In most of them the dimensions and types of screws and shims are given.

Hans

tobydmv
Posts: 85
Joined: Wed Apr 16, 2014 4:59 am

Re: AAU Fixing Screw m4x10

Postby tobydmv » Fri May 08, 2020 7:36 pm

ducwiz wrote:Have you looked into a parts catalog, especially for your bike? In most of them the dimensions and types of screws and shims are given.

Hans


Yes sir, thats where I pulled the m4x10 and verified that the driven gear and shaft parts are universal across models but the AAU is not. The scrambler and monza have different aau. My bike started as a scrambler and was converted to monza DC ignition. I've been trying to get it right ever since. Thanks Hans!

Jordan
Posts: 1162
Joined: Fri Dec 24, 2010 11:29 am

Re: AAU Fixing Screw m4x10

Postby Jordan » Sat May 09, 2020 12:02 pm

Don't dismiss the AAU as being probably worn out.
This part of the Ducati singles that is well designed and generously proportioned.
I have rarely seen one that is worn out, just some dead ones that had rusted due to poor storage.
It is easy enough to check for smooth operation. After disassembly and cleaning, lubricate and reassemble to the bike.
It should be easy to twist the cam with fingers, and letting it go will allow it to spring back.
A sloppy action could be due to worn springs.
A minor issue with the AAU is that it can be installed 180 degrees from correct position, easy to put right.

A battery-less Ducati "points" single uses an AAU with a reduced ability to retard, so it is inherently more prone to kick back if not given a swift kick.


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