1964 Atlas

Steve Highfield

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Feb 12, 2021
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I finally got my Atlas up on the operation table.. While trying to get it running i noticed the Magneto has a weak and intermittent spark.
I have a Distributor for if it if the mag is bad.
But before i pull the mag what can i check on the mag to trouble shoot it to confirm it's a goner?

P.S. I'm going to have a lot more questions as this build progresses
 
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Points cleanliness and gap on both ramps of the cam ring.

Cleanliness of the high tension slip ring.

Are the HT brushes not worn away?

Is the earth brush free to move in its holder?
 
Triton Thrasher said:
Points cleanliness and gap on both ramps of the cam ring.

Cleanliness of the high tension slip ring.

Are the HT brushes not worn away?

Is the earth brush free to move in its holder?
Click to expand...
Unfortunately Triton Thrasher's trouble shooting advice won't tell you if the condenser is bad. The symptom of a bad condenser is decent starting followed by rough or non existent running once the bike warms up. Also, if the mag has never been rebuilt, 99.9% of the time the condenser is bad. The only reason I don't say 100% is that I have no proof that this is true for a bike with a mag that was stored in a climate controlled room for 50 years.
 
+1 With Bodger. I will go to 99.99%. Even NOS condensers are likely to be bad after being on the shelf over 50 years.

To clarify TT's comment regarding point gap: gaps should be equal on both ramps.

If you kick over the engine with both plugs removed and both plugs grounded to the engine, you should get a blue spark from the plugs. A yellow spark is weak.

Slick
 
Thanks guys..
I appreciate the info. I'm going to take it off of the bike and give it a good going over.
In the research i've done says i need a special tool to center the pinion shaft..
Is there a trick to it so i don't need the tool?

I will keep you guys up to date of my findings with the mag
 
I have gone down this route three times in the last few years, just stripping old K2Fs greasing the bearings & replacing the insulators & oil seal. Each time they have started to fail once hot. The bikes always restart when they have cooled down but misfire a lot. The last time was on my Atlas. In future I will just send them to Tony Cooper in Birmingham for rewinding/rebuilding. The capacitor will need to be replaced in yours at the very least, so unless you have the skill to rewind the armature you would be better off sending it to someone who has.

Martyn.
 
Steve Highfield said:
Thanks guys..
I appreciate the info. I'm going to take it off of the bike and give it a good going over.
In the research i've done says i need a special tool to center the pinion shaft..
Is there a trick to it so i don't need the tool?

I will keep you guys up to date of my findings with the mag
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There's a way to center the pinion shaft by turning the camshaft to where there is tension. To be honest I've never understood it but I'm sure you can look it up by doing a search here. I use a dummy timing cover and Andover sells a tool that does the same thing.
 

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I would not DIY. To my knowledge, there are several special tools necessary to disassemble and reassemble a K2F, as well as rewinding the armature with about a mile of very fine wire, centering the armature, and giving the magnet a Gauss boost.
Better to send it to a competent Lucas magneto re-builder.
While the cost may seem high, keep in mind it includes the armature rewind fee, plus many new parts. What you might save DIY is minimal, and you might damage something.
I see you are in NS, Ca. I do not know anyone in Ca to recommend, but on the east coast of the US, there is none better than Doug Wood of Boyertown, PA <dougwood@netzero.net>

BTW, To elaborate on the post by Matchless .... starting cold and dying hot is textbook capacitor failure. The old Lucas cap has got to be replaced by a modern capacitor of proper specs.

Slick
 
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Bodger said:
There's a way to center the pinion shaft by turning the camshaft to where there is tension. To be honest I've never understood it but I'm sure you can look it up by doing a search here. I use a dummy timing cover and Andover sells a tool that does the same thing.
Click to expand...
I'll do some research on the subject :)
 
texasSlick said:
I would not DIY. To my knowledge, there are several special tools necessary to disassemble and reassemble a K2F, as well as rewinding the armature with about a mile of very fine wire, centering the armature, and giving the magnet a Gauss boost.
Better to send it to a competent Lucas magneto re-builder.
While the cost may seem high, keep in mind it includes the armature rewind fee, plus many new parts. What you might save DIY is minimal, and you might damage something.
I see you are in NS, Ca. I do not know anyone in Ca to recommend, but on the east coast of the US, there is none better than Doug Wood of Boyertown, PA <dougwood@netzero.net>

BTW, To elaborate on the post by Matchless .... starting cold and dying hot is textbook capacitor failure. The old Lucas cap has got to be replaced by a modern capacitor of proper specs.

Slick
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I would never attempt it myself.. I might just go the route of the distributor. I might sent the mag out to have it rebuilt later

I have a Buddy that has own a electric motor company for the past 30 years. He's an electrical genesis
 
Update- I've checked and cleaned the points and checked the gap. It was at .020 i set it to .012.
-Cam ring is in good shape
- slip cleaned and in good shape
- HT brushes cleaned and in good shape
- Ive got and nice fat blue spark now :)

I bench checked the mag and i only get spark in one direction turning it. Counter clockwise. Clock wise nothing.
The mag only produces spark on a higher rpm range. low rpm nothin
 
Low turning should give you at least a fair kick whilst holding the bare HT lead with your hand.....
Do you have any oil inside the magneto? If yes it should he drained, cleaned and new oil seal fitted.
 
Steve Highfield said:
Update- I've checked and cleaned the points and checked the gap. It was at .020 i set it to .012.
-Cam ring is in good shape
- slip cleaned and in good shape
- HT brushes cleaned and in good shape
- Ive got and nice fat blue spark now :)

I bench checked the mag and i only get spark in one direction turning it. Counter clockwise. Clock wise nothing.
The mag only produces spark on a higher rpm range. low rpm nothin
Click to expand...

Very important ..... Do you have equal gaps on each ramp of the cam ring?

I am confused .... you say you have a nice fat blue spark, then you say you get nothing at low rpm. Which is it?

Slick
 
Bernhard said:
Low turning should give you at least a fair kick whilst holding the bare HT lead with your hand.....
Do you have any oil inside the magneto? If yes it should he drained, cleaned and new oil seal fitted.
Click to expand...
When i turn it slow i get nothing.
There was oil in it when i took it apart.
 
texasSlick said:
Very important ..... Do you have equal gaps on each ramp of the cam ring?

I am confused .... you say you have a nice fat blue spark, then you say you get nothing at low rpm. Which is it?

Slick
Click to expand...
Yes i get a consistent gap on both ramps
I have it attached to a variable speed drill. when i turn it over slowly i get nothing but when i give it a good speed i get spark
 
Steve Highfield said:
When i turn it slow i get nothing.
There was oil in it when i took it apart.
Click to expand...
Oil seal is gone . Did you give the armature and the interior of the mag body a good clean using electrical contact cleaner, clean the brushs and rotor where the brushes run on?
Also remove HT leads and suppressor caps, check copper wire is shinning copper, test without suppressor caps first then test at low speed again.
I still weak or no spark, magneto is either tired or capacitor needs replacing. The DIY type capacitor would be cheapest.
BTY, is yours a Lucas Competition Magneto?
 
Steve Highfield said:
Update- I've checked and cleaned the points and checked the gap. It was at .020 i set it to .012.
-Cam ring is in good shape
- slip cleaned and in good shape
- HT brushes cleaned and in good shape
- Ive got and nice fat blue spark now :)

I bench checked the mag and i only get spark in one direction turning it. Counter clockwise. Clock wise nothing.
The mag only produces spark on a higher rpm range. low rpm nothin
Click to expand...
Hate to be a "Debbie Downer," but unless you know that the condenser/capacitor has been replaced your test is meaningless. With the original condenser/capacitor the mag can throw a nice spark and start easily, but then it will leave you on the side of the road ten miles later after it has been warmed up by the running engine.
 
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