GSXR1100 possible CDI issue?

[redeem ouzzer]

Took my standard GSXR1100L out today, the nature of the bike and the fact it’s my every day road bike means it rarely gets revved hard however I went for an overtake in second earlier on a slow moving car and it misfired but it felt really rough, not like hitting the limiter. Did some experiments and found that it’s misfiring at about 9 to 9.5k, which is accompanied by the tacho bouncing around like its signal is also braking down. I’m thinking CDI failure. Below this the bike rides perfectly, wiring harness was new last year, bike runs dyna mini coils. Tested the charging rate and it’s hard capped at 14.68V regardless of revs so I don’t think that’s an issue. Any input would be appreciated, I know the black boxes are 30+ years old now so failure wouldn’t be entirely surprising, however the couple of failures I’ve seen previously gave total loss of spark or loss of spark on one output (I.e. 1-3 or 2-4 dead). The tacho going mad leaves me pretty sure it’s electrical.
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Be a REAL MAN!

[Robby]

I would poke around the low tension ignition wiring first. I presume it is also 30 years old. A wire being a bit loose or internally broken so it's not making good contact with the vibrations from high revs could be a culprit.

Utter bugger to work out a test for though, apart from setting a multimeter to resistance and wiggling things.

[redeem ouzzer]