Hi. Can anyone recommend somewhere to test / rebuild my Magneto please? (Close to Sheffield would be a huge bonus)
This is what I've done so far, in search of that illusive spark:
Cleaned ignition points & pickup with brake cleaner
New plug
New cap (non resistor)
New HT lead
I've tried the HT lead without a plug too but there's no sign of life.
I'm an absolute novice when it comes to 4 strokes and old bikes but I'm thinking that it might be a magneto problem?
Any help or advice would be much appreciated as I'd love to hear her running.
Thanks
hi fraz, the points can get dirty, try and get some emery paper in between and clean the contact point.
Well, FTW Magneto's are in Sheffield, although I have never used them.
It might be worth looking at the Bright Sparks or The Magneto Guys websites for advice, although they may be a little overwhelming if you're new to this.
Andrew Guttman at Priory Magneto's is a Club member, and I can recommend APL and Armoto.
Unfortunately, magneto overhauls take quite a long time, but you may be able to get it running by making up an insulated points centre screw together with a U shaped brass contact strip under the screw, shaped around the points carrier to contact the carbon brush of a new plastic end cap. Then you can run a 6V coil and condenser.
Good luck.
Hi,
Maybe a bit basic but is the slip ring clean and the pickups making good contact?
I think there was storey a while back about poor quality pickup brushes not being very conductive so perhaps check them for any resistance.
A test that I used many years ago, but would attract a prison sentence today, was to get my youngest bother to put his finger in the mag against the slip ring whist I turned it quite quickly by a piece a shoe lace wrapped around the end of the shaft. The quality of the expected spark could measured against the decibels of the resulting scream.
I only managed to use this method once.
I suppose a cats tail would work just as well (only kidding).
Dave.
Quote from: DAVE BRADY on 25 Nov, 2023, 19:51
Hi,
Maybe a bit basic but is the slip ring clean and the pickups making good contact?
I think there was storey a while back about poor quality pickup brushes not being very conductive so perhaps check them for any resistance.
A test that I used many years ago, but would attract a prison sentence today, was to get my youngest bother to put his finger in the mag against the slip ring whist I turned it quite quickly by a piece a shoe lace wrapped around the end of the shaft. The quality of the expected spark could measured against the decibels of the resulting scream.
I only managed to use this method once.
I suppose a cats tail would work just as well (only kidding).
;D
Dave.
Thanks for the tips. I'll see if my brother will come and help ;D
I've cleaned the pickup and whatever is inside that the brush contacts, with brake cleaner and both are clean now.
Not sure how to check the resistance of the brush though?
I've measured the depth of (presumably the ring?) And compared it to the length of the brush, to confirm it's long enough to contact - and it is.
Much appreciated
Quote from: DerekAnderson8 on 25 Nov, 2023, 17:07
hi fraz, the points can get dirty, try and get some emery paper in between and clean the contact point.
Thanks.
I forgot to add that I had cleaned the points with wet & dry before spraying with brake cleaner
Quote from: Steve.S on 25 Nov, 2023, 19:39
Well, FTW Magneto's are in Sheffield, although I have never used them.
It might be worth looking at the Bright Sparks or The Magneto Guys websites for advice, although they may be a little overwhelming if you're new to this.
Andrew Guttman at Priory Magneto's is a Club member, and I can recommend APL and Armoto.
Unfortunately, magneto overhauls take quite a long time, but you may be able to get it running by making up an insulated points centre screw together with a U shaped brass contact strip under the screw, shaped around the points carrier to contact the carbon brush of a new plastic end cap. Then you can run a 6V coil and condenser.
Good luck.
Thanks for all your suggestions, that's great (although I admit to not understanding the latter half :-[
I'll try the local company first and thanks again
Quite often just cleaning the contacts don't work ,it's best to take out contact and rub on carborundum stone ,if bike has been standing for sometime the contacts get hard scale on them ,
Hi,
As far as I know the brush should offer no resistance as it is only a way of touching the HT lead to the strip on the ring.
Dave.
You've had good suggestions thus far and probably at the limit of what you can do without more knowledge and/or equipment. I have a fair amount of electronics experience (valve era) but when my magneto was weak and failing I sent it to BrightSparks in France for overhaul and then I did a 'deep dive' on learning about the M01 and its foibles such that the last couple I did myself (except for armature rewind). I have test gear and pullers.
I have on the bench a bare mag that I am going to strip, add new bearings and seals, and put a Thorspark system in as it seems a neat piece of kit (I ran 500 Daytonas for years with Lucas Rita and then Boyer). I converted my Dynamo and regulator to 12v.
Down side is that you need a good battery and there is the risk of catastrophic failure ie without warning which happened to me once (Shepherd's Bush roundabout in rush hour for a RITA and outside my house with Lumenition on my MG (my father wisely had me set up a spare points plate for the MG so I was up and running again in 1/2 hour, bike was recovered by Hamrax for Boyer fitting.
No spark when you have clean points, good HT cable, clean pick up and ring suggests failed armature or cracked/shorted slip ring.
Was the bike sold to you as running?
Quote from: neil1964 on 26 Nov, 2023, 10:47
You've had good suggestions thus far and probably at the limit of what you can do without more knowledge and/or equipment. I have a fair amount of electronics experience (valve era) but when my magneto was weak and failing I sent it to BrightSparks in France for overhaul and then I did a 'deep dive' on learning about the M01 and its foibles such that the last couple I did myself (except for armature rewind). I have test gear and pullers.
I have on the bench a bare mag that I am going to strip, add new bearings and seals, and put a Thorspark system in as it seems a neat piece of kit (I ran 500 Daytonas for years with Lucas Rita and then Boyer). I converted my Dynamo and regulator to 12v.
Down side is that you need a good battery and there is the risk of catastrophic failure ie without warning which happened to me once (Shepherd's Bush roundabout in rush hour for a RITA and outside my house with Lumenition on my MG (my father wisely had me set up a spare points plate for the MG so I was up and running again in 1/2 hour, bike was recovered by Hamrax for Boyer fitting.
No spark when you have clean points, good HT cable, clean pick up and ring suggests failed armature or cracked/shorted slip ring.
Was the bike sold to you as running?
Thanks.
It was bought as "not having run since 2016, when it ran just fine"
Am I correct in thinking that the bike should run / produce a spark even with no battery fitted?
Yes
One of the beauty's of these old bikes with a magneto is that they do not need a battery or dynamo working to run completely normally (later B31s went to distributor and alternator which absolutely need a good battery).
The battery is needed for lights and horn only.
Common failures on a magneto will be the things that you have already elimnated (we hope)
After that capacitor (condensor) failure is common. They usually exhibit weak spark as they are wayx paper type and subject to age/temperature degrdadation and access can only be acheived by stripping the whole lot down and removing the brass end cap to get at the capacitor.
Quote from: neil1964 on 26 Nov, 2023, 17:44
Yes
One of the beauty's of these old bikes with a magneto is that they do not need a battery or dynamo working to run completely normally (later B31s went to distributor and alternator which absolutely need a good battery).
The battery is needed for lights and horn only.
Common failures on a magneto will be the things that you have already elimnated (we hope)
After that capacitor (condensor) failure is common. They usually exhibit weak spark as they are wayx paper type and subject to age/temperature degrdadation and access can only be acheived by stripping the whole lot down and removing the brass end cap to get at the capacitor.
Thanks for confirming
I use Armoto for rebuilds. V good, not cheap but near you
Takie HT pick-up and check resistance shall be close to 0 OhMs (0-10) I guess. Basic multimetr provides it wit knob set to Omega sign.
One capbe pres against brush and other on te end of HT pick-up where cable goes....there is metal contact point....check if it is clean .....as said almost no resistance shall be noticed...