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Hi All, Thing is setting up the rotor without a dowel is not always as simple in real life.

Pre fit plate slots centered. Mark case at the sight hole location to pre aline rotor.

Set motor to 38b using tdc tool or rotor mark. I’ve found I always turn motor in running direction to take up back lash in gears. If you must back up, over back up then come forward again.
Install rotor loose & center slots in plate when installing. Get down & really sight in the paint dot/rotor. Slip rotor as needed, then snug bolt.

If pointer doesn’t match tdc tool 38b mark rotor at what tdc tool shows.

Start motor & strobe check. Even with our best attempts at set up you can run out of slot.

Cure. Think about how much you need to adjust rotor & which way to center slots close enough to get timing. Remove plate, rotate motor forwards to 38 mark. Sight this in. Mark rotor & case with sharpie pen. Loosen rotor & slip it as needed using marks to know how much you moved it. Snug rotor. Install plate & re strobe. Here is where many go wrong…, no marks they guess at how much to move rotor. Get frustrated & start filing slots. Especially if they only need 1/8” or so.

Quality of wiring & charging system as a whole is very important. When fitting EI is extra important as they are more sensitive to low voltage/current flow.

As expected the plate slotters are the same ones that do poor wire connections. At the same time don’t address the corroded, split bullet connectors & sleeves, ground points, fuse holders etc. You address all of this & these bikes will very, very seldom leave you walking.
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If the holes in the last photo once held the pillar bolts they were in the wrong holes. The holes hidden by the plate are where the pillar bolts should be. At least they are that way on my 68 and the 72. Bolts straight up and down, noon to six, not tilted. Can't remember what the tilted holes are for, maybe someone else does. My 68 has a Pazon. The 72 a Boyer.

Last edited by desco; 10/14/21 7:02 pm.

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yes , reset the rotor taper .
In my experience a simple thing , they tend to pop right off when lightly tapped at 90 degs.

i see some rust and blowby on that old stator plate , with its oversized slots ... but it still looks usable .
I would have tried just adding some custom oval washers
over the slots and under the pillar Bolts to help spread the load on and over the PC board .
a pair of oval washers can hide how how much adjustment slot is left ,
but would probably be a good idea for even a brand new stator .
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I would like a copy of the stl file for the 3D printer!

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Originally Posted by Carmackle
I would like a copy of the stl file for the 3D printer!
I have published the STL file and SKP (Sketchup) file on Thingiverse.

https://www.thingiverse.com/thing:5021746

If anyone uses this or improves it I would love to know.

Thanks
Peter


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
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Thanks!

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So, I seem to have found why a previous owner butchered the stator plate.

I fitted the new stator plate and set it up at 38BTDC using the correct (clockwise) timing hole. Tried to start the bike and no joy. Got a very occasional backfire but didn't try to run.

After quite a bit of fiddling about and head scratching, I thought I would try it on the anticlockwise hole, as that was how it had been before. I did this by moving the rotor clockwise. Sure enough, it started. Didn't run very smoothly but it ran enough for me to get the strobe light on the timing marks.

What I have found is that the timing is not advancing with the revs. It is static. I think that the unit is stuck at full advance. This is why it wouldn't start when set up correctly but when I moved the rotor "forward" I have effectively retarded the timing (I think) to a point where the bike will start.

I have checked my battery and given it a charge and it seems to be ok (holding 12.4v ish)

My feeling it that the Boyer "box" is knackered, but I thought I'd ask here if anyone knows of any other possible causes? It's a Micro MKIII btw.

Many thanks
Peter


1963 3TA (TwentyOne) Half Bathtub
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Originally Posted by Peter Williams
What I have found is that the timing is not advancing with the revs. It is static. I think that the unit is stuck at full advance. This is why it wouldn't start when set up correctly but when I moved the rotor "forward" I have effectively retarded the timing (I think) to a point where the bike will start.


Check the black/white and black/yellow wires aren't swapped over somewhere between the pickup plate and the Boyer box. (Or swap them over at the pickup and see what happens?)

"Timing Plate Wires"
http://vintagebikemagazine.com/technical-articles/Boyer-trouble-shooting/

Last edited by L.A.B.; 10/18/21 9:08 am.
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Thanks L.A.B. - That's a pretty comprehensive article.

First thing that I did notice is it says that the magnets should be strong enough to hold the weight of the rotor. Mine aren't. I noticed how weak they seemed when I took the rotor off.

Will check the wiring as well.

Cheers
Peter


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
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Originally Posted by L.A.B.
Originally Posted by Peter Williams
What I have found is that the timing is not advancing with the revs. It is static. I think that the unit is stuck at full advance. This is why it wouldn't start when set up correctly but when I moved the rotor "forward" I have effectively retarded the timing (I think) to a point where the bike will start.


Check the black/white and black/yellow wires aren't swapped over somewhere between the pickup plate and the Boyer box. (Or swap them over at the pickup and see what happens?)

"Timing Plate Wires"
http://vintagebikemagazine.com/technical-articles/Boyer-trouble-shooting/

+ 1 lab .
Considering the modification to the stator plate , it almost make sense
that the trigger wires could be wired backwards too

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Deleted.

When reversing the wires, moving the rotor 70° could be correct.

Last edited by L.A.B.; 10/18/21 10:23 am. Reason: Correction
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I'll check it out. Struggling with how / why someone would swap them over though.

Last edited by Peter Williams; 10/18/21 10:27 am.

1963 3TA (TwentyOne) Half Bathtub
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Originally Posted by Peter Williams
I'll check it out. Struggling with how / why someone would swap them over though.

I don't think it's done on purpose just that old stained black/white could be mistaken for black/yellow and a faulty box not advancing [retarding] still can't be ruled out.

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Quick check with a multimeter followed by unwrapping lots of black tape around cheap and nasty connectors at the "black box" end...Black/Yellow goes to Yellow/Black (and I do mean Yellow/Black!) And Black/White goes to Red/White!!

At the Stator the wires emerge as Black/Yellow and Black/ White, so somewhere in-between there are some more connectors. Under the tank I guess.

Bottom line...they do seem to be crossed over. No time now to re-do the timing but, fingers crossed, that will be the problem. Hopefully get a chance to look again tonight.

Can't believe someone would start "modifying" the stator plate before checking the wiring. :-(

Thanks L.A.B. for the pointers.


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I just tossed a battery that read 12.3V but did not have enough power to keep the oil pressure light turned on. 12.7 or more is better on a fresh battery. Get your striped wires sorted then wire the black box straight to the battery. If it still won't run it's got to be the battery or the box. Hope you have a comfy garage.


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Regarding why black/white and black/yellow may be swapped around on some bikes, below quote is from Haynes Triumph repair manual, 1990.

"Since the left hand set of contact breaker points (black and yellow lead) corresponds with the right hand cylinder......"

By swapping the wires AND resetting timing 180d difference, the bike will now have left set of contact breaker controlling left cylinder; much easier to remember left to left and right to right. I don't play with EI, so am not sure if this is a practical swap in an EI system. But it does explain swapped wires at some point.......

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Originally Posted by Deadstiffcatt
I don't play with EI, so am not sure if this is a practical swap in an EI system. But it does explain swapped wires at some point.......

The black/yellow and black/white are used for a different purpose so that's not what happens with EI.

http://vintagebikemagazine.com/technical-articles/Boyer-trouble-shooting/
"Timing Plate Wires"
"The polarity of the timing plate wires is important. The Black/Yellow and Black/White wires must be connected color to color. Make sure the Black/Yellow wire on the timing plate is connected to the Black/Yellow in the wiring harness and the Black/Yellow wire on the ignition box is connected to the Black/Yellow in the wiring harness...

...If these wires are connected incorrectly, the ignition advance feature will not work properly. Also, the box will fire 70° from where you want it to.
"

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RESULT!

Swapped the wires, set the static timing and kicked it over…

…started first kick and now advances with the revs.

I don’t have time to do too much more tonight (and the neighbours wouldn’t appreciate it).

Thanks again L.A.B. (and everyone else that’s offered help)

I have some wire on order, so will get rid of the spurious wires and just have what I need in the right colours (also add a common earthing point). Did the same with my 3TA and have found it to be much more reliable.


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That M/C is 53 years old. If I have learned anything in my 60 year relationship with these old turds it is this; If you assume that every previous owner was either mechanically inept or too cheap to buy needed parts or both, you will be right most of the time. If you want piece of mind, plan on replacing everything that affects reliability. I build them to start easy, get me where I want to go and get me back home. It takes a while and costs money to do it right. In all my travels getting home has rarely been an issue.


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Take a Voltage Reading - The voltage of a battery is a good way to determine the state of charge. Here's a handy table:
State of Charge Voltage
100% 12.7 - 13.2
75% 12.4
50% 12.1
25% 11.7
Discharged 0 - 11.6

From the "battery Stuff" web site. Lots of good info here and a pleasure to deal with.


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