It could be the CDI but if you have a Multimeter test the coils even though you swapped them.Put the meter on 20k ohms and test between the thin LT(Low tension) wire and the plug cap inner.I should read anything between 7 and 13k ish.Then do the test again with the plug cap off.Then test the plug cap.It should have continuity or a very low resistance.
This will eliminate them from the problem.They can cause all sorts of problems even if they appear to look good.I've just had to swap a bad coil as it started to drag the right hand side down and also I've no really good spare plug caps left in my spares box so have just bought/sent for a couple.


