Comet series c ignition timing

M

Matt Mckeown

Forum User
Non-VOC Member
Can anyone help with me try to work out what's going on with my magneto? I tried to start the bike after a long layup. There is a good spark at the plug but it wont fire in any way shape or form despite good fueling and plenty of kicks.
I decided to do a static timing check to eliminate a timing issue. However much to my surprise, after connecting a tester between the centre bolt of the points and the magneto case, I have a closed circuit regardless of the position of the points, (open or closed). I removed the points and checked them to see if there was an isolation problem but that was fine. but after reinstalling them The same problem was there. I don't understand this. I have a regular spark coming out of the lead and yet, apparently, there is a permanently closed circuit at the points. Confused
 
G

Garth Robinson

Well Known and Active Forum User
VOC Member
Matt Mckeown said:
Can anyone help with me try to work out what's going on with my magneto? I tried to start the bike after a long layup. There is a good spark at the plug but it wont fire in any way shape or form despite good fueling and plenty of kicks.
I decided to do a static timing check to eliminate a timing issue. However much to my surprise, after connecting a tester between the centre bolt of the points and the magneto case, I have a closed circuit regardless of the position of the points, (open or closed). I removed the points and checked them to see if there was an isolation problem but that was fine. but after reinstalling them The same problem was there. I don't understand this. I have a regular spark coming out of the lead and yet, apparently, there is a permanently closed circuit at the points. Confused
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You won't get that regular spark if you leave the bridging wire in position when you turn the motor over.That's how the magneto cut -out on the handlebars works.
 
vibrac

vibrac

Well Known and Active Forum User
VOC Member
Thats also why if you want to electrically signal when the points open with a bulb you have to slip a bit of insulation(I use heat shrink tube) over the taper bolt in the mag centre to insulate it.
 
greg brillus

greg brillus

Well Known and Active Forum User
VOC Member
That's because of the inbuilt resistance in the primary circuit of the armature, you need to remove the points holding bolt as Vibrac described to test in that way. Or else there are new testers available and not too expensive that will check these circuits with all still connected. Perhaps the shaft has slipped on the ATD taper.
 
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