RS1 Coil Values

[AndyD]

Hi and thank you for letting me join.
I have just stripped cleaned and rebuilt my first Lister D but cannot get it to run.
Fuel seems good as I can smell it coming out of the exhaust so I suspected the spark was bad.
Cleaned up the points and set them, fitted a new condenser and have a new HT lead and plug.
I suspect either the coil is duff or the new condenser is.
The condenser does seem to charge up with a multi-meter set to MΩ and discharge when set to Volts.
The coil resistances (when disconnected) are 4500Ω on both coils to the earth connection and 0.8Ω from the coil wire to earth (see attachment).
When assembled both sides of the points are continuous to earth even when they points are open.
I can't find any of the document showing what good resistance values should be.
Any help greatly appreciated.
AndyD

[cobbadog]

Go to Youube anf watch some clips there to show you how to test both condensor n coils. I have tested and replaced  a few SR1 n RS1 coils after they failed the tests.
A good coil in generalshould read. from HTR lead to ground - 3800 - 5000k on 20K setting on your meter.
Secondary should read from secondary winding wire to groun - 0.3 - 0.6 Ohms on 2K setting.
Some meters now are automatic in selec ting the correct range but my old bastard is a manual one. I think to test your condensor it is a different method from as you described, but I might be wrong. Now days I have a bench top testing meter that tests all types of magnetos plus will heat the coil to operating temps to test again looking for tracking or internal arcing inside.

[AndyD]

Well rechecked everything twice and still no spark. So sat the magneto in front of a fan heater for half an hour and hey presto it sparks like a good-un.
Engine now starts with half a turn of the handle every time. Had a few fuel leaks to sort but easy done.
 

[cobbadog]

Glad it is running again. What do you think the issue was, just water ingress?

[AndyD]

I can only assume it was some moisture somewhere so fingers crossed it stays dry 😳

[cobbadog]

Hopefully that is all that was wrong and that it stays in working order. Not sure where abouts you are in the world but if you do need another coil they are readily available from any magneto rebuilder. Ring around as prices will vary.
I have a supplier here in Australia that rewinds his own product and seals it and posts very quickly for a very good price.

[ajaffa1]

Hi Guys, these magnetos have an insulating seal between the two armature bearing races and the chassis of the magneto. A spark will always take the shortest route to ground, if these cardboard insulators are damp guess what happens.
Glad you got it running.

Bob