Engine Trouble new CDI, no spark

[Yolandi]

hi recently had trouble with my still new 66cc, found the previous problem was the stock CDI being a bit rubbish, bought another off ebay (with removable ht lead and cap boot but essentially the same)
started up first time and ran fine then the other day just died and wont do anything, no spark at all however with a clip on flash cap it is producing a very dim flash, sticking the old CDI on it is producing a very dim spark but doesnt start (like before)
i went online and found some testing numbers and here is my comparisons, (base is the normal range according to the testing sheet)

are these numbers right? the base and my own readings?
is the cdi dead again after a week of use?
ic checked the magneto and its producing a little over 25 volts while pushing the bike along at jogging pace

 

[Deleted member 12676]

http://www.dragonfly75.com/motorbike/testCDI.html

 

[crassius]

check the ohms on your mag coil - we had some last year that read about 480ohm rather than the usual 350

these seemed to blow out one leg of the rectifier in the CDI leaving a very weak spark - often would blow out a CDI in less than 10min run time, but CDI would still function as long as motor was turning at 20MPH or so

 

[Yolandi]

just checked across the black and blue wires, blue wire and engine casing and between the magneto soldered terminals, 310 ohms on all accounts

 

[crassius]

I'd say the problem isn't in the mag then - I have in the past seen two bad CDIs in a row, but that is rare these days unless some ebay seller is dumping old stock on the market

no meter test of CDI is reliable due to capacitors & diodes & transistors inside - I built a tester at my shop to check both spark & timing, but that seems beyond what a typical rider needs

just have to try another if you think it is bad (don't forget to check wire connectors for dirt/corrosion)