The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: u28909z on 21.08. 2014 20:43

Title: Basic Dynamo Query
Post by: u28909z on 21.08. 2014 20:43
Hello all.

I am new to BSA, having just aquired a 1957 A10. I am trying to remove the dynamo to refurbish it. Is it necessary to remove the inner timing cover to liberate it, or is it possible to wiggle it out through the engine plates?

Thanks
Title: Re: Basic Dynamo Query
Post by: bsa-bill on 21.08. 2014 20:48
you need to take the timing cover off, possibly you could wiggle it enough to shake off the chain and then wiggle it out but you'd need to be a bit of a Houdini to get the chain on again *smile* *smile*
Title: Re: Basic Dynamo Query
Post by: Beezageezauk on 21.08. 2014 20:57
As Bill says, it's a bit of a struggle but it is possible to remove the dynamo, complete with driving sprocket without removing the inner timing cover.  However, if the dynamo has a belt drive on it the driving pulley will need to be removed in order to get the shaft through the aperture in the inner cover.

Beezageezauk
Title: Re: Basic Dynamo Query
Post by: a10gf on 21.08. 2014 21:08
Another thing with the cover still on (assuming dynamo gets out and can be refitted without removing cover, never tried that!) is finding the correct chain tension when refitting (assuming you have a chain), usually needs a few attempts at tightening the dynamo before the chain is ok. Too slack and 'anything' can happen, too tight and it's goodnight to bearings and chain.

And welcome aboard! Intro post\pictures in Bikes & members always appreciated.
Title: Re: Basic Dynamo Query
Post by: KiwiGF on 22.08. 2014 01:21
On my 56 swingarm it is not possible to remove it without first removing the inner cover so it comes out towards the right...... I suspect some engine plates have larger clearance than others which is why it is a case of trying it to find out  *conf*

A mate opened the plates out on his a10 so he could remove it from the left side.....so im not sure if some plates are different from the factory or been customised.
Title: Re: Basic Dynamo Query
Post by: duTch on 22.08. 2014 03:45

 As per all the above, but fairly sure I've done it, by rotating it backwards to remove the chain, and for the sprocket to clear inner case aperture, then immediately back the other way (forward) for the interface flange to pass through the R/h engine plate which I think has a slightly larger oval hole....

                                            *????*
Title: Re: Basic Dynamo Query
Post by: tiggy on 23.09. 2014 18:15
Hi, it may be too late but I have just done this on a 1958 A10 if it helps.
The outer timing case can be removed without taking off the exhaust. The strap needs to be fully loosened and pushed up to give as much play as possible. Looking from the drive end, rotate the dynamo anti-clockwise to loosen the continuos chain which can the be lifted off the dynamo drive but left on the other cog. Push the dynamo away from you enough to remove the cork washer. I then found it easier to pull/wiggle/rotate the dynamo from the other side to remove it. It did come out without too much trouble.
When refitting, the Haynes Manual states 1/4" slack in the centre of the chain is what you are looking for.  I found the dynamo had a tendency to want to move, loosening the chain when tightening the strap, so had to jam it with a lever to hold its position, but got there in the end. It was easier than I expected.
Good luck.
Title: Re: Basic Dynamo Query
Post by: u28909z on 24.09. 2014 21:03
Thanks for the replies.

I think I struggled because the dynamo has had an SRM belt drive fitted (not by me), and the pulley would not pass through the hole in the inner case.

In the end I didn't need to remove it as after another run of around 5 miles the dynamo started working properly, and is still doing so.

I have had this with another bike (Triumph) after it had stood for a year without being ridden. I assume the residual magnetism in the field coil pole shoe can weaken with standing, and needs flashing.
Title: Re: Basic Dynamo Query
Post by: Rgs-Bill on 24.09. 2014 21:40
I understand about a long ride to get the Dyno working again after a long sit, BUT HOW COME no one here is talking about flashing the field side of the Dyno, with the hot wire from the battery.  Remove both the D wire and the F wire from end of the Dyno, and flash 2 or 3 times 1 second flashes to the field pole of the dyno.  This should be done anytime the battery is removed for a time, to make sure the regulator and the Dyno are on the same polarity, so as to not ruin the regulator.  Is some one here  knowledge able on if this is necessary to do to a DVR-2 regulator and Dyno setup, or all solid state regulators also ????
Title: Re: Basic Dynamo Query
Post by: muskrat on 24.09. 2014 22:04
I'm not sure if it's necessary every time the battery is removed but it won't hurt. The DVR2 is pole sensitive in that you buy a +ve or a -ve . As you disconnect the F & D wires at the dynamo and flash with another piece of wire the DVR2 is not connected and wont suffer unless you flash the wrong way.
Cheers
Title: Re: Basic Dynamo Query
Post by: bsa-bill on 25.09. 2014 08:36
If a bike is not ridden for some time it's logical it might have lost it's field residual charge but also maybe ( more so) a brush is stuck, a good ride and a pothole or two will just jar it back into action.
A a young apprentice electrician way back (don't ask when) we all carried a fine file to modify brushes a tad so they slid in their holders a little easier, washing machines main culprit.
I did the same to my dynamo once
Title: Re: Basic Dynamo Query
Post by: Andreas Larsen on 25.09. 2014 23:03
(...)the field side of the Dyno, with the hot wire from the battery.  Remove both the D wire and the F wire from end of the Dyno, and flash 2 or 3 times 1 second flashes to the field pole of the dyno.

Question just to clarify - which side would be the "hot wire"? In a +ve earth system that would be with a wire from the -ve pole? Or is it the other way around?

Andreas

Title: Re: Basic Dynamo Query
Post by: morris on 25.09. 2014 23:08
You got it right Andreas. On a +ve earth you flash it with the -ve pole
Title: Re: Basic Dynamo Query
Post by: u28909z on 01.11. 2014 19:50
My dynamo stopped charging again. I accidentally connected the battery on the wrong way, and thought I might have blown the DVR2 regulator. I tried the regulator on my rigid Triumph, proving it was fine. So off with the outer timing cover to attempt again to remove the dynamo to test it. I put a spanner on the dynamo nut and noticed the driving pulley was spinning free of the shaft. When I tried to tighten the nut it wouldn't tighten - stripped thread.
I had to clean up the thread on the shaft with a die, and a new nut (locktited) should hopefully be a long term fix. 
I can confirm that getting the belt tension correct is tricky.