The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: bsa-bill on 23.08. 2010 18:36

Title: Maggie question
Post by: bsa-bill on 23.08. 2010 18:36
Trying to test the recondition Magneto on my non starting Rocket Gold Flash
So swapped the Maggie, put the recondition one on my Flash (which starts easy), Fired first kick so I'm thinking that the maggie is allright, except it was missing on one for quite while, went on to two and seemed happy.
I decided at this point to try out a colour tune kit I got some time ago as this bike does run rich, especially on pilot jet ( I reckon smaller jet or blocked air way), well yellow flame so yes it's rich and no amount of adjustment gets it any different, at some point I need to take this carb off and clean it and/or swap for smaller pilot jet.
Now here's the thing when adjusting to slower tick over the colour tune stopped, I presume this meant no spark.
If this is the case that this magneto is only sparking on one side at slow tickover and coupled to the fact I have a larger engine sprocket (1 tooth more meaning  the engine will not turn as far with one kick ) could this be a reason for non starting?
And one further Query, I have read the mails about checking the timing with a lamp or buzzer, I cannot get this to work on either of my Magneto's, checking with a meter I get continuity all the time whether point are open or closed - I'm stuck with the Rizla method
Title: Re: Maggie question
Post by: muskrat on 23.08. 2010 21:10
G'day Bill,
                doesn't a yellow flash mean lean, blue is good ? I used a colortune on the cafe and adjusted to a blue flash, runs great.
Sorry can't help much with the maggie, I use Boyer.
Cheers
Title: Re: Maggie question
Post by: a10 gf on 23.08. 2010 21:27
Quote
checking with a meter I get continuity all the time
Actually not, there is approx something like 0,5 ohm difference (this may vary a little from mag to mag) between open and closed, you need a very good digital meter to measure it properly, & a normal buzzer will not react to such a small difference, just keeps on buzzing. Any normal meter will have big problems to reliably read such small resistance values, and the value will jump all over the place as the armature is rotated, so IMO a meter is not suitable for this kind of job.

Try the lamp +battery method (http://www.a7a10.net/forum/index.php/topic,1375.msg10365.html#msg10365), & the LED based testbox (http://www.a7a10.net/forum/index.php/topic,2539.0.html) seems interesting, see frost.co.uk (http://www.frost.co.uk/item_Detail.asp?productID=9247&frostProductName=Magneto+Timing+Light)

... and moved to Lucas board (ref the title).
Title: Re: Maggie question
Post by: bsa-bill on 23.08. 2010 21:35
Just had another read of the instructions Muskrat, It states adjust at normal idle to show yellow flame (rich) then weaken to achieve bunson burner blue.
I didn't get this far as the heavens opened up here and the garage roof leaks, tomorrow maybe.
Thinking about the maggie, if it is producing one spark it should produce two - I'm guessing one pickup or lead is dodgy
Title: Re: Maggie question
Post by: sparx on 23.08. 2010 21:41
Yellow on the colortune is rich, blue is stoichiometric (big word for "right"  *smile*) white is lean. My A10 seems happier slightly rich.
  If the maggy is sparking on one side only at lower rpm I'd suggest you have a look at the points gap, make sure it's ok when open in both positions.
  If the points are good try swapping the pick-up/lead/plug from one side to the other and see if the lack of spark swaps side as well. I had this problem a short while ago, it was a duff plug that had hardly done any miles before failing.
 I couldn't seem to get the bike running good using the resistance check method, despite being careful to get the piston position spot-on. I don't know if it was just good luck or what, but a fag paper worked better for me.
Title: Re: Maggie question
Post by: bsa-bill on 23.08. 2010 21:45
Thanks a10gf - I have a maggie on the bench so a good time to try a method or two, my meter has several Ohm ranges but I wouldn't class it as a good one, seems to take a while to decide what to display.
I have in another shed an old AVO that my dad bought at a Radio rally long time ago, it's about the size of a breeze block, haven't the heart to throw it out, I should spend a bit of play time with it
Title: Re: Maggie question
Post by: bsa-bill on 23.08. 2010 21:56
Cheers Dave - points gap should be ok  I checked  before I put the maggie on the bike

Quote
If the points are good try swapping the pick-up/lead/plug from one side to the other and see if the lack of spark swaps side as well. I had this problem a short while ago, it was a duff plug that had hardly done any miles before failing.

Yes I think that,s tomorrows task, swap leads, it wasn't the plug as it was the colourtune side that was missing.
I don't smoke so no Rizlas around but I did find some paper 0.001 thick

Positive side of things are that the maggie itself does produce sparks and the maggie off the flash is good and can go on the project eliminating one cause of non starting
Title: Re: Maggie question
Post by: a10 gf on 23.08. 2010 22:00
I remember the AVO's, beautiful devices (but not suitable in any minuscule ohm range). This one maybe http://vintageradio.me.uk/testeq/Avo_8.jpg ?. Keep it.

But in any case, (imo) it's very bothersome and unreliable to use resistance measurement\meter to try to get the points\timing right.
Title: Re: Maggie question
Post by: sparx on 23.08. 2010 22:15
And you checked in both cam positions Bill ?

  I used one of those big old Avo meters a lot when I was an apprentice. Found out the guarantee runs out just over half way between the bench top and the floor. The number of swear words my foreman knew was truly amazing.
Title: Re: Maggie question
Post by: Triton Thrasher on 24.08. 2010 07:52

Now here's the thing when adjusting to slower tick over the colour tune stopped, I presume this meant no spark.

No- more likely you have restricted the flow of fuel and air until it stopped firing, although still sparking. 
Title: Re: Maggie question
Post by: BSA_54A10 on 24.08. 2010 12:16
Have another look.
You should be able to see the spark
So if there is a spark & no flame then there is an fuel related problem.
If there is no spark then it is an ingition problem.

I use a colour tune all the time.
It is my first test on any suspect engine so I can start looking down the correct street.
Saves a lot of time.