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CDI is best, but most of mine have old school points mags. I'm talking very early "70's points systems on mine which have been totaly reliable i must say, but cdi set ups from very late "70's & into the "80's on yamaha generaly give very little trouble & 9 times out of 10 the reason for 'no go' will be the source coil in the flywheel as the windings are very fine wired compared to an old points mag source coil. For-instance a mag source coil will have a resistance of around 2 ohms where a cdi source of about the same diameter will have 350 ohms & to take that to the extreme--a source coil for my old yz125 will have 1437 ohms [by memory] for a coil of approximately the same diameter as the others. I cut one of those yz ones apart once & the wire strands were finer than my hair--when i had hair!! lol. Sorry if i mis-interpreted your question. Think what i was getting at was cdi coils being finer wired can fail through heat & vibration more often than points coils.