The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: bsa-bill on 09.08. 2011 21:06
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RGF up to it's usual old trick today, was going to book it in for an MOT but thought it prudent to give a run out just to make sure all was well -HA
it's been starting in the shed no problem, it went the first two miles fantastic, up hill in top with ease and no pinking.
Pulled in two miles out to adjust idle that was a bit fast, it stopped on the lower idle, from then on poor running, difficult starting mostly only possible with bump starts down hills, I ran out of hills and had to be rescued.
There is a spark - sometimes not bad sometimes a bit weak and often coming from around the plugs centre electrode rather than from it ( I did change plugs several times with new plugs also).
Haven't ruled out carb problems yet but here's a thing, I tested for a short on the kill switch, put a meter from ground to the coutout screw on the end of the Maggie, I get 110 to 120 ohms - should this be, this maggie worked fine on my Flash 7.5 pistons, the RGF has the 9.1 pistons back in and the 357 cam (bad move I think)
Any ideas more than welcome
I don't have that much patience these days that I can afford to squander it on this project, saving grace is the old Flash. utterly reliable, starts with a short prod, ferried me to work for about three weeks without a hitch
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Is the slip ring dirty from a badly-inserted HT brush?
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Hi Bill
How long ago has the mag been checked or rebuilt? I am told that mags die of old age after a while.
If you could find a NOS mag that has been on the shelf for more than about 10 years you would probably have trouble with it.
May be that it worked on the flash at a lower comp ratio but would not work on the RGF as you would need a stronger spark at the higher comp. Also may be breaking down as it gets hotter which would explain why it worked ok in the garage.
I spent ages sorting out a backfire / misfire / starting problem on my SR and I finally bit the bullet and had the mag rebuilt and the bike runs like a clock now - best money I ever spent!
Jim
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Hi Triton Thrasher and Jim
Just in so haven't had a chance to look any further at the bike
Good point TT I had just fitted new pickups, will look closely at the slip ring, it is producing a spark though but maybe not in the compressed air of the cylinder.
Jim I have another maggie on my flash, both give the same result on the project, I take your point a bout the higher compression.
The symtoms are as you would expect from a maggie with "warm starting problems", It was reconditioned at FTW around three maybe four years ago ( I have the receipt so could be more precise)
it was also back to them last year as the cam had slipped, something I could have fixed myself but with it giving trouble thought it should be checked out.
However this time it will not start even cold, should at least give a pop now and then even if I've changed the odd setting a tad here and there (don't think so though)
Plan to check the slip ring as TT suggests also the carb before going any deeper.
May swap back to 8.5 pistons but leave the 357 cam in ( has any body run this combination ) if the higher compression is duffing up the maggie then the choice is get it reconditioned again ( somewhere else maybe) or go electronic ( install two slim 12 volt batteries and a switch arrangement *smiley4*)
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The reason I thought of the slip ring is because I have misaligned a brush myself (more than once!) and it puts a black ring around the bottom of the slip ring. The plug sparks in open air, but when under compression, the HT current tracks around the carbon mark on the slip ring and sparks the other plug!
Easy and cheap to diagnose- hope it's so simple, but which of use ever has such luck with magnetos?
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Thought that was it TT, there was a bit of carbon which I cleaned off, checked the gap and went to get some known good plugs to try it.
Decided to test the plugs for continuity with a meter, lot of variation one new plug failed completely.
However I got two good plugs and tried the maggie, nice fat blue sparks
Next checked out the carb, nothing wrong in there so put it back on and went to try the bike - nothing, kicked for a good while before taking the plugs out to check for a spark, no spark whatsoever
And the plugs were not wet, tried two other plugs that had given sparks when trying the maggie - nothing.
I hear what you all say about the high compression killing the spark but surely it should produce a spark again when back out of the cylinder, it disappears?
What in dozen or so revolutions can happen to a magneto that is producing a good spark to kill it, no resistor caps or plugs used, I'm more than a little rusty on the black art of windings and high voltage but my mind points me to thinking about the condenser (due to the fact I can't think of anything else).
Think I'll give FTW a ring, they reconditioned it
Also found some info on plugs today that I'll post elswhere
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Once, the thick wire broke off from the condenser on mine, but I think that's unusual.
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Think this has the makings of something unusual TT *smiley4*
Couldn't resist one more go, been down the shed gave the slipring another clean ( was ok), took the earth screw out and looked at it uit it back.
Wondering about the end cover, can't see what could go wrong with it although it could have got swapped with the one off my other bike but there both the same I think.
I jury rigged a fuel pipe to the carb and tried it, it fired - once, took the plugs out and tested for spark and they did spark so tried again, it fired - once, still sparking outside the cylinder too so some progress maybe.
As I've had the carb off maybe it needs a tweak, tomorrow
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You can ru with no end cover if you can stop the cam ring falling out. Is the points spring keeping clear of the cam ring?
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Is the points spring keeping clear of the cam ring?
Ah now I spotted that and thought I was onto something, it is very close and might indeed touch but only on the part of the cam where the points are closed in which case all the parts are earthed together anyway or have I got that wrong and they should not be earthed to the frame but just to each other.
back to the continuity thing, there is no continuity from the central pin (that holds the point plate in) to the maggie case, but there is some (as said before)from the kill button on the end over to the maggie case - going to swap them over today, also check meter reading on old flash for same thing.
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The centre screw should have continuity to earth with little resistance. Shouldn't the test current go from that screw, to the condenser and thence through the thick LT winding to the armature yoke, which is earthed to the casing by one or more earth brushes?
Something like this:
(https://www.a7a10.net/forum/proxy.php?request=http%3A%2F%2Fwww.avweb.com%2Fnewspics%2Fmagchec2.gif&hash=4738ac6b1f8e5ec6fcb0a0e172cef56f3f0c444f)
Sadly, most magnetos which act as if cursed or haunted turn out to have an intermittent/deteriorating HT winding fracture don't they?
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thanks TT that's really helpful, my 12 month apprenticeship in a Electrician come radio/tv shop some fifty years ago seems of little help to me these days *dunno*.
Do you know which point ( fixed or moving is from the primary windingand therefore the capacitor) I can do comparison with other maggie.
Have tested the end cover from the Flash's maggie, it has a brush that is twice the length of the RGF one, it also shows around double the resistance, looks like what I'm measuring is the resistance of the brush in the end.
I do have a spark now (don't ask how or for how long) but the carb is not right, bike fires once after flooding then stops, not enough fuel I think, it's coming out the rear of the carb.
You know I can't remember braking any mirrors but..................
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Bill, the fixed point (ie the one we adjust) is the live one. It's insulated by a mica washer and other little bits and bobs that go round the small screw that holds it to the cb backplate. The sprung, moving, point is earthed always through the screw on its tail, to the cb backplate and then through the earth brush(es) etc. It doesn't matter electrically speaking if the spring blade touches anything else that's earthed - but it mustn't touch the brass bit that holds the live point obviously or you'll have no sparks as the points will have been bypassed. Could have been your prob? unless the cut-out / kill button wasn't right - ie permanently shorted to earth and thereby same result? (If the camring hits though, anything could happen as the points might never even operate properly!)
The live point is connected (at the drive end of the mag) to the live side of the capacitor and the live end of the LT winding. It's done by a link wire that goes from the bottom of the cb centre-screw through a channel cut in the laminates of the armature - the coil end, the link wire and the capacitor live are soldered up with norralot of room around them. The other end of the LT coil is earthed along with the capacitor itself (and the HT winding for that matter) also at the drive end.
The kill button brush or contact blade (or whatever) to earth should show an Open Line except when the button is pressed - when it should be as near to 0 ohms as possible . . . If there's permananet continuity, then no sparks natch.
As TT says, there'll be continuity to earth through the centre screw (or live cb point, same thing), that's the resistance of the LT coil only - about half an ohm. Which a cheap meter seldom measures with any precision. Earthed point to mag casing or frame should be zero ohms - but same problem with cheap meters and there's usually a bit of unwanted resistance in any brush and spring arrangement. If readings are obviously high but seem to be correct, then the earth brush is a likely prob as suggested.
Best of luck!
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Thanks Goily and TT - plenty to digest and test there, I think the resistance I measured could be down to the carbon brush on the end cover screw ( to kill switch)
I have an old AVO meter that I started to clean, was my dads, I think I'll get it together and test the maggie with the info you've both provided.
Now some good news, Les (friend ) had heard of my problems and came around to investigate, makes a difference when you can share the kicking.
We has little success so decided to go through all the things that usually go wrong other than the maggie, carb, valves, timed to correct cylinder, discussed the events of Tuesday starting with how well it went at first, Concluded something must have broken or moved.
Checked the ignition timing, heel just at the ramp when cylinder at the 3/8th btdc, it was --- thats when the lamp lit, it should be there when fully advanced not at retarded.
Possibly moved when I bump started it or just not been tight enough, at best timing has slipped at worst tooth/teeth of the fibre pinion. will find out tomorrow.
This still does not explain the disappearing spark
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OK I got around to making sure all was well re timing both valve and ignition, and had the carb to bits once more.
Put new plugs in and tried it - zilch, the plugs spark outside the cylinder and light up a plug tester when in the engine but it wont start.
We were looking at the plugs and thinking they were dry but thinking logicaly when Les swped the plug leads over we got an almighty crack, I tried the same thing and got two loud reports and on a second kick another bang that sounded like it was in the crankcase, so there must be fuel mixture in there (or maybe this is how the universe came to be, matter from nothing *smiley4*)
The other point to this is that when you swap the leads you then have the spark formed in the cylinder that is not under compression.
This is leading me to believe the Maggie is just not upto the task, both my Maggies perform the same in this engine perhaps I should accept that neither of them is up to sparking in compression over 7.5 .
Now to meter readings, my meters lowest resistnce range is 0 - 200, with the points open readings between centre screw and earth or either points and earth is around 5.6, with points closed the same readings give around 9.
tell me if I'm doing this wrongs folks
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I think you're running around in circles. Probably nothing to do with the maggy? I'd triple check timing, rag stuck in manifold,gods wrath, time of day etc....
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Bill, I think you have confirmed that both your mags are on the way out - probably only a matter of time when they will not run at the lower compression also.
If the spark is not strong enough it will have problems arcing across the plug gap at higher compression - alternatively it may find a "better" path with less resistance through the mags internals if the insulation is breaking down so not get as far as the plugs.
Couple this with the rubbish we forced to buy as fuel in the UK then any mag problems are intensified.
The problems I had were so similar to yours and in the end I bit the bullet and had the mag rebuilt. It did not run well at first but a new set of N4s cured it and it now rides like a different bike.
Hope you get it sorted soon so you can get some miles in before the winter.
Jim
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Jim thanks, you've confirmed what I think is going on, I have been thrown my the fact that both Maggies performed the same way.
Also ordinary plugs (N3,4,5, B6,7) wont spark in the pot and give a weak spark outside but two Bosch plugs I have do give a spark in the pot ( I had it running today) but they are peculiar plugs, very thin electrode like an Iridium plug but apparently silver they are not resistor though , they have an extremely thick metal base, unfortunately they also soot up on a short time (cold plug), no doubt if I sorted out the Bosch code I might find plugs that I could use, not ideal though I should be able to get reliable starting without stocking up a hoard of exotic plugs.
I had a call from old firm yesterday, bit of work to do so I could be flush in a week or so, think I might keep the Maggie as a spare for now and get it looked at when time and dosh allow, meantime I think I might dabble in the Pazon direction, a plan is hatching - involves two batteries and some sort of switching arrangement to allow use and charge of either, thereby always having a fully charged battery on board.
Could be I'm a glutton for punishment
Thanks all once again for the help
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G'day Bill,
if your going down that path why not go for a dvr2 reg to convert the 6v generated by the dyno to 12v for the ign and lights, running 1 12v bat.
Works well on both of mine.
Cheers.
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Hi Musky
I have a v-reg 6/12 volt reg from http://www.norbsa02.freeuk.com/index.htm (http://www.norbsa02.freeuk.com/index.htm) and had the dynamo upgraded to 12 volt and run a 12 volt battery, batteries are a lot smaller these days so two slim ones should fit in the space, some sort of mechanical switch-over would give an option ( to be sure to be sure) *lol* *lol*
So I'm looking at the Pazon Sure fire as it works down to 8 volts and has a 7 1/2 year warranty, apparently made by former management at Boyer ?
Looked at the Wassel one too, looks sound as it's encased in silicon but it only comes with one year warranty, would have thought these days they should have enough faith in it to give a bit more than that.
Also have been looking at Bosch plugs, I'm impressed with the ones I have got ( the only ones that will start the bike it seems, that fact alone sort of points to the maggie as the weak spot)
Found some that are N4/N5 and such compatible and with the silver thin wire centre electrode also non resistor, got a couple ordered.
Found them on this site http://www.boschsparkplugs.net/411.asp?pt=1 (http://www.boschsparkplugs.net/411.asp?pt=1). lot of interesting stuff in the "plug problem" section, kind of explains why plugs go dead and for me gives some reason as to why every indication of the plug sparking but no fire - interesting reading.
Been at work for the last week so just getting down to some maggie detective work this afternoon (in between British Super Bike and Moto GP)
Yep I'm thinking along the lines of trying the electronics and keep he maggie for a spare, then sell it in five years or so as a rare RGS component ( five years on I might have this bike going) *smil*
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Hi Bill and All,
Have a read of this article on plug fouling *idea*
http://www.gsparkplug.com/shop/fouling-shortingout-problem-modern-plugs-champion-vs-ngk/
I had a set of NGK's give me trouble during the week, The bike was running and starting fine
After refuelling is started to miss and became harder and harder to start *conf*
I blamed the petrol ?? but when I went and refilled the next day the problem persisted ????
A new set of plugs and problem dissapeared *smile*
I was on the Irish National Rally so 500 odd miles during the week *smile* *smile* *smile*
Regards
John O R
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I've read that one John, certainly fits in with a lot complaints about plugs.
I'm also thinking there is something in the theory that that common plug types are not quality controlled at all (sorry forget who stated this) which might explain why the more exotic type work better, perhaps they are tested
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Got around to doing a comparative test between my two Maggies, (trying to stop running around in circles *smiley4*, none taken Wilko)
Checked out the meter leads and battery just to be sure
Centre screw removed - points open - resistance in ohms
Mag 1 mag2
fixed contact point to mag body 7.4 69.5
moving contact point to mag body open open
moving point brass pivot pin to mag body 7.3 69.5
with points closed same tests 12.4 130 - 95 fluctuating
tomorrow I'll nip up the road to Bobs and see what his magnetos read, we did all the ohms, watts, volts , amps stuff a school so I do have a rough idea of it all but that was a long time ago, today I know continuity from an open circuit but beyond that I might as well subscribe to the smoke theory
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Bill,
I have just measured the resistances of a newly rewound armature and I get -
High tension - 5200 ohms
Low tension - 0.5 ohm
This is without points or slipring fitted.
Trev.
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Hi Trev
Many thanks
Tested mate Bob,s spare maggie yesterday and got same result as Mag B so I've got an odd man out, which just happens to be the one on the RGF.
Will take it off today and copy your test and see what I get, also a look inside will see what condition it's in and anything obvious, should contain a nice clean newish looking rewound armature *dunno2*
Will decide today which way to go,probably will try Pazon , will then have a spare maggie but as Bob remarked about his spare Maggie "it's probably doing better than money in the bank these days)
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dismantled the Magneto today, slight problem with the safety screws, both were extremely tight and a fair bit of corrosion on them, the head broke off one of them so not ideal, had to break off the bottom of it to get the armature out.
I can get the 0.5 ohm reading but the high tension ( testing from the brass on the slip ring to the taper on the drive shaft ) is erratic, I get 1500 to 800 and many in between but they just flash up on the meter and then disappear.
Also pretty black grease in the bearings and are they meant to be slackish?
any way a Pazon surefire ordered along with a billet housing, I'll sort the Magneto at my pleasure
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Hi Bill,
You need to check from the high tension slipring to the centre bolt that holds in the points (points rotor removed)
The inner end of the high tension winding is connected to the low tension winding so unless the mag is complete and the points closed there will be weird readings??
quite often if using a digital meter the HT winding will show open circuit
this is because the connection is only pushed into the slip ring and not soldered or crimped
HTH
John O R
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Ah thanks John, will do that tomorrow although I think I've already done it.
Have ordered a Surefire from Mr Goff and will build up the Magneto with new bearings and seals as a spare
I'll get a photo of the armature and what I presume is the capacitor (or two) encapsulated in the end of the armature, they look a bit old fashioned what else could they be though?
Armature looks like it's been dragged past a safety screw at some time , big deep scratch along it's length (wasn't me honest).
Many thanks once more to all who have chipped in on this saga
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Had my mag rebuilt recently and two capacitors were fitted opposite each other supposedly to improve the armature balancing - I think only one was fitted originally.
I had erratic readings too on the mag pre rebuild and John O R mentioned at the time that the HT winding is only pushed under the slip ring so I put it down to that. It seemed that I got various readings on different parts of the ring and at differents pressures on the probe.
If only Joe Lucas had made guns we would never have had any wars *smile*
Jim
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Hi Jim
I think I have two capacitors fitted also, are these encapsulated into the end of the armature, they don't look too modern to my eyes
and they are different in detail although they could be facing different ways.(the capacitor not my eyes)
Writing on them is as follows
on first one on the next
RIFA 275 V~ SH
pme271M 14 RJ ( Csa )this looks like a trade mark
5v9 250 VAC
40/110/56/B
Found the manual for my meter so got the "resolution" for the ranges
take your point about the variable readings.
so I get 0.5 ohms Lt 4.32Kohms HT seems low compared to what you guys are getting, armature windings shorted somewhere?
Certainly has been out before as big scratch would testify, also evidence of wires soldered to edge of armature on both sides?
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Hi Bill
I never actually saw my new armature as I asked my Manx Norton restorer friend to rebuild the mag for me and he sent off the armature to a guy he has used for years. He mentioned that when he got the armature back it had the two capacitors and the armature had been sealed with resin. He also said that the capacitors had been replaced with a modern type - I can vaguely remember back in my apprenticeship in the sixties that capacitors were paper and foil construction and there are much better materials available now and the components are a lot smaller and more reliable.
It certainly seems that rewinders earn their money having looked at a few posts previously which had links to the process - the wire used in the HT winding are about the thickness of a human hair *eek*
Electronic ignition does seem a good alternative but there is something strangely appealing about a device (mag) where you just turn a spindle and sparks come out of two wires with no complicated circuitry involved. When they are working well there is an certain attractiveness to the simplicity of the design and not a lot can suddenly go wrong as they seem to die gradually with plenty of warnings and can normally get you home.
The downside of electronic ignition is that it is reliant on the battery but your idea of a separate battery using a split charge sytem for the ignition should solve that - it is probably similar to that used on caravans to prevent flattening the car battery while using the van electrics.
If you go down that route it would be interesting to see the results.
Jim
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Hii Bill,
4.3k ohm is absolutely fine no worries there, Original windings were about 4k, with modern insulating materials some winders get some more turns in
I cant make sense of some of the numbers on the caps fitted to your mag??
The problem with a lot of modern caps is that they arn't man enough to absorb the high current charge
I have had to repace several from well reputed rewinders
The original foil and mica caps were able to withstand the pulses much better,
Sean Hawker has hand made capacitors like the originals, Not cheap though *ex*
Independant Ignition supplies capacitors seem to be ok, Havn't seen one fail yet
There have been a lot of dodgy sliprings about in recent years,
pitting and tracking on the insulated part of the ring, use a megger tester from the brass segment to the opposite side
What happens when the slipring tracks is that the mag is trying to fir both plugs at the same time *eek*
HTH
John O R
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Hi John.
I'll see if I can get a pick of the capacitors, tried this morning but my camera died on me, dodgy batteries (Poundstretcher), they show 1.69 volts but last about three. minutes and still show 1.69 volts - what is it about me and electrics?
Pazon arrived today with magneto replacement body, I have had a study, seems straight forward, I'm short of a fuse though and a decent switch, tried the magneto replacement body on the bike, leaves a very useful looking hole down the rear of the engine, thinking I might resite my filter at some time.
I'll take some photo's as I install it,might be useful to someone in the future
interesting remarks you make re the slip ring, I know an electrician who used to service the estate I worked on, I'll get it tested with him at some point
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Interesting thread Bill.
I think your erratic meter readings are caused by the capacitor. To show this properly you need an old fashioned moving coil meter. The needle will sweep as the internal meter battery charges it. Digital meters just show different readings and are not effective at this. I had my armature rewound after considering the various options. Its between the capacitor dying of old age and the thin HT winding going green and shorting through after several years. One thing you could have tried is wiring an old style car points capacitor across externally to the centre kill connection at the mag and earth. This will help a dying mag for a while. But the only reliable solution is to rewind or go electronic.
Stu
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Hi Stu
From advice I've had here it seems the Mag checks out good apart from the maybe the capacitors or the slip ring, I have two maggies both show the same results (both refurbished at the same place?)
I do suspect the capacitors but have no way (or knowledge) of testing them with the digital meter I have two AVO meters my dad bought long time ago, the small one (just a little bigger than a modern one) is very difficult to move the (knob) and the other one is about the size of a shoe box, need to find time to look at them.
I'm half way through installing the Pazon, I got a call to help out with seed sowing yesterday so a day lost but helps pay for the Pazon *smiley4*
Will report back when I get it in
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Well Pazon fitted (pictures taken of the procedure, will post when time allows)
I fitted a pair of not to clean N4's that had been used and failed to start it in the past just to eliminate any advantage new plugs would give, tried them out of the cylinder first, nice fat spark on both ( at the same time ).
With a little trepidation tickled, choke on, eased till it wheezed, a nice determined swing - BAAROOM.
ran it for a minute adjusted the pilot ( 2.5 turns for best running, probably could go back to 25 pilot but hey 1 turn from normal - good enough)
stopped it a couple of times and restarted, first kick each time but need to try the same after a run
So far so ..............................
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Great news Bill, I know you will love it, even with the down side of having to have a good battery. I got it on all three Beezas.
After your run and it's nice and hot re-do the pilot adjust.
Cheers
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Hi,
I've no experience with these antiques but below is a 'Tech Tip' copied from the latest HMCCQ club magazine.
< It ran last time out? now there is no spark from the magneto?
Don't despair - yet! Try a Dave Dettmar 'tech tip'.
Remove the contact breaker assembly from the front of the magneto.
(Take out the centre bolt and the assembly, after a wriggle to loosen it, should come out)
Clean the carbon brush behind the assembly & brush track inside the magneto.
The track especially can accumulate a film of oil that with age (& when cold) may thicken and act as an insulator to block the low tension current flow.
Re-fit the assembly, it goes back with a key to locate it in position.
Then try it again - maybe this time ................? >
Seems to make sense. I don't think the centre bolt should be used as the earth path.
Aren't the bearings and the shaft supposed to be insulated from the frame with a fibre thingy?
and any resistance in the low voltage side will likely have a bigger impact on the high voltage.
cheers
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Modern replacement points don't even have the brush?
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I don't think the centre bolt should be used as the earth path.
Nor did Lucas. The centre bolt is the live path.
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Modern replacement points don't even have the brush?
Nor did some original brass plates.
My magnetos have all had an earth brush at the drive end.