RS 125 (Rotax 122) CDI faulty?

[andy_uk]

Having just fitted new crank bearings etc after a lovely seize up...I now think my CDI is on its way out
It was running fine for the first week after the rebuild but today it started playing silly buggers...
The bike starts fine, but after a few minutes if I go over 3k revs it either dies completely or misses one hell of a lot.
I have an electronic rev counter which takes its signal from the input side of the coil and when it starts missing the rev counter reads around 250rpm (even though the engine is obviously doing a lot more than that while still coasting...). I can hear it firing approx 4 times per second with the throttle wide open (which tallies with the rev counter reading).
If I let it drop back down to tickover (or let it stall & restart the engine) it's fine again until the dreaded 3K revs is reached.
Presumably I can rule out the coil (for the reason stated above regarding where the rev counter is connected to).
I've checked cable routing etc as well as the connector(s) between the pickup and CDI, no amount of 'cable wiggling' appears to make any difference.
So...
Does this sound like a classic "fooked CDI" or should I check anything else?
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Aprilia Classic 125, GS500E, ER5-A1, ER5-C4, ER6 & an XJ6 project frame...

[uberkron]

check your stator/cdi windings. Before condemning the module. Had a weird coil/cdi issue on my zip where it would limit at about 3.5k but coil and cdi are integrated in my case but what you describe could well be your coil failing and shorting the cdi output.
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i ride a zip 50 2smoke. It overtakes a hundred times a day.

[andy_uk]

My multimeter has a frequency counter on it so I should be able to check the flywheel pickup...
I also have another coil (not the right one, but it may suffice for testing purposes...hopefully!)
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Aprilia Classic 125, GS500E, ER5-A1, ER5-C4, ER6 & an XJ6 project frame...