Author Topic: auto advance mystery  (Read 1074 times)

Offline Happy Hans

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auto advance mystery
« on: 30.10. 2018 19:28 »
Hello,

I have a problem with installing my auto advance unit. While tightening the double threated centre nut I recognized that the A/R unit goes not deep enough onto the conus of the armature, it doesn't fits firmly, even didn't touches it . Seems wether the fibre sprocket is too thick, because it touches the inner timing case before the A/R unit touches the conus, or the armature of the magneto goes not deep enough into the timing case, or something else. By the way the k2f magneto is freshly rebuilt by david lindsley and I'm very satisfied with his work.

I would be glad if somebody have an idea what causes the problem.

Thanks in advance, Hans

Online chaterlea25

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Re: auto advance mystery
« Reply #1 on: 30.10. 2018 19:38 »
Hi Hans
Is the "U" shaped washer fitted under the nut on the A/R unit ?
it sits into the dished washer/shim
If this is missing the nut may not clamp the unit
It is easily made by cutting a slot from a suitably sized flat washer

John
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1963 RGS (ongoing)

Offline Happy Hans

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Re: auto advance mystery
« Reply #2 on: 30.10. 2018 19:48 »
Yes it's fitted, and when tightening the nut only slightly it will come loose when I try the kickstart some times. When I tighten the nut firmer the whole drive train goes firm, then it is not possible to kickstart again. So I thought that it has something to do with the contact that the fibre sprocket has with the inner case.

Online trevinoz

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Re: auto advance mystery
« Reply #3 on: 30.10. 2018 20:08 »
Maybe the magneto armature is not protruding far enough due to shimming on the wrong end or the taper is worn.

Offline Happy Hans

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Re: auto advance mystery
« Reply #4 on: 30.10. 2018 20:29 »
I dont believe that there is something worn, because the magneto is totally overhauled, but that it has something to with the armature is not coming out enogh maybe could it be, but then I am down because that should not occure after I payed a huge amount of money for the mag renovation. Maybe it is worth to messure the length of the armature end coming out of the housing and have a comparision to another one ,or to messure the cone somehow.

Thanks, Hans

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Re: auto advance mystery
« Reply #5 on: 30.10. 2018 20:45 »
Measure it Hans and post result.

Offline Happy Hans

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Re: auto advance mystery
« Reply #6 on: 30.10. 2018 20:56 »
I measured it. The distance between the housing flange and the end of the taper is 24,7mm.
Sorry I only have it in mm's.

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Re: auto advance mystery
« Reply #7 on: 30.10. 2018 21:33 »

 Hans- I had the same thing with my ATD and initially I made a conical brass shim to pack it out, but when I did my rebuild 7 years ago, I figured the only real option was to carve some material from the casing behind the unit - that was about the time I bought the Dremel...*work* I have somewhere the details of how much I carved

 I bought a spare maggie at a swap last wekend , and these are the measurement of the taper /thread;
 Case to end of thread;      23.52mm  (0.926")  ......
 Taper length;                   11.36mm  (0.448")
 Thread length;                 11.76mm  (0.463" )   

 My regular maggie is in hosptal at the moment, will measure that when I have it back


Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Offline Happy Hans

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Re: auto advance mystery
« Reply #8 on: 30.10. 2018 21:47 »
Carving some material, I think could be an option if there is not too much necessary to get contact between the unit and the taper. Dutch do you mean the distance between the inner timing case or the maggie case to the end of the thread?

Thanks for your help.

Offline morris

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Re: auto advance mystery
« Reply #9 on: 30.10. 2018 22:18 »
Hi Hans, I measured an ATD I had lying around.
The taper depth is 18 mm to where the thread starts.
The taper protrudes about 9.5 mm behind the gear.
The gear is 15 mm wide
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Offline Klaus

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Re: auto advance mystery
« Reply #10 on: 30.10. 2018 22:29 »
Hi Hans,
please check the 2 bolts comming througt the housing. May be the rear one is too long, so the gear get in touch.

Klaus


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Re: auto advance mystery
« Reply #11 on: 30.10. 2018 22:36 »
Hi Again Hans,
Can you "feel" the unit touching the engine cases?
On one bike a long time ago I found that the nut was going to the end of the threads and still the unit had not seated on the taper!
Eventually I had to remove the first 1 or 2 internal threads on the nut

I would remove the magneto from the engine again, then trial fit the unit on the shaft,
If it tightens up ok then go to plan "dremel"
If the nut will not tighten on the taper make a thicker U shaped washer as a first move

John
1961 Super Rocket
1963 RGS (ongoing)

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Re: auto advance mystery
« Reply #12 on: 30.10. 2018 23:46 »
 Hans, it's from the bearing flange on the Maggie case, right next to the bearing and shaft( the bolt flange is another 2.45mm )
 I measured it with digital caliper,  the analogue ruler is just for demo.
 This is I believe the correct maggie for my '53 engine BA10
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Offline kiwipom

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Re: auto advance mystery
« Reply #13 on: 31.10. 2018 03:23 »
Guys surely this unit should go together without talking a grinder or a hacksaw to it,  presumably Happy Hans had this working before the mag was reconditioned. I would go back to the guy who did the work and see if he can figure it out, cheers
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Re: auto advance mystery
« Reply #14 on: 31.10. 2018 03:52 »

 Yes KP, one would think so,  but we sometimes reluctantly need to work with what w have
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia