Vintage Dirt Bike Q & A

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PostPosted: Wed Mar 24, 2010 9:14 pm 
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Joined: Wed Mar 24, 2010 7:25 pm
Posts: 1
Hello all,
I have lost the spark on my 74 1/2 GP 400 (see a short clip of it here at http://www.youtube.com/watch?v=NmUsV7ry3SM) and I could use some advice (other than drop the bills for a PVL)
Last time I took it out to race at Perris, it would not start and I gotta get it ready for an ARX race in April. It has (what I think is) the stock magneto, points, condenser, single wire motoplat coil etc. (motoplat coil may not be stock?)
I removed the kill switch, still no spark.
Check continuity of points. With points closed, continuity between ground and primary coil wire....with points open, still continuity. I think this is wrong.
Remove condenser wire, no change.
Remove coil wire from points, points work fine, ie no continuity with points open.
Check coil resistance: Primary to ground...1.4ohms
High tension (spark plug wire) to ground...7.6k ohms
My Clymer book shows a different (two wire) coil and says the resistance between high tension wire and ground should be 3k ohms.
Is the coil my problem?
Any advice or tips would be appreciated, It has always been easy to start before.

Thanks
Don


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