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Lucas K2FC magneto trouble help

9419 Views 17 Replies 9 Participants Last post by  Tony the torch
This is not a call for help, but rather a tech tip that may help you with your K2Fc magneto if you are having trouble with a poor/no run condition. The time this happened to me, it was on a fresh build, complete motor build, complete mag rebuild. And the bike ran like a champ for two weeks before this issue reared its ugly head.

Backfiring out exhaust, stalling out, and eventually a "no-run" condition, only occasional firing of either cylinder. It was much like having very fouled plugs, and having the kill switch "on".

Upon further trouble shooting, it began to run, but only with the cap off (even without the kill wire connected).

The issue turned out to be a slightly loose (not rattling loose, just not completely cranked down) center stud. After tightening the stud, it ran like a champ again, instantly.

I hope this info helps another one of us fools who are addicted to old British iron.

Cheers, Dan.

This is not the mag in question, but it is a K2FC...
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This past year I have been pulling my hair out trying to get my 1958 TR650 back on the road. I had made a big mistake letting the bike sit for a couple of years since I was riding my Harley all the time another story back to the K2F mag problem. I finished having the valves ground down and the jug milled due to the head gasket blowing between cylinders and I installed a new carb. After reassembly of the engine the bike was back firing out the exhaust, thinking I had a timing issue I proceeded to re-time the mag. I found that the bike would start right up 1st or 2nd kick but after running for a bit it would start back firing upon acceleration. I was then thinking that the K2F mag had to be the issue even though it appeared I was getting really good spark. I removed the mag and set it up the my bench and using a drill was able to spin it to check the spark of each plug. They both where firing with a very nice blue spark, confused at this point I removed the points cover performed the same test and I noticed that the points where firing twice but 180 degree apart. I replaced the capacitor with a new product EasyCap Retested and found the points only firing once during rotation. The Bike is running like new. Hope this helps any ? drop me a note. Cheers Mike
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