Jimmy13 posted this a few months back, several people tried it with great results. do a search for MC16 CDI issues DO NOT DESPAIR

To all you MC16 owners out there......

I have recently had issues with the CDI units on my bike well one in particular (MC16 has 2). This unit controlled the tachometer/rev counter also and so the key symptom was the rev counter going nuts when the ignition was turned on and dropping a cylinder when started.

Having searched the globe I found various used units at rather high prices in south africa and australia but considered £120+ to be excessive for a used unit.
I finally gave in and rang Wemoto for ideas they put me in touch with David Silver spares who I currently have a brand new unit on order with from Japan for £103 inc vat and delivery. GREAT !

In the meantime I found this guide on a XL600R forum ref CDI's of the same year...ironically the part number is almost identical and the XL also had 2 x CDI units made by the same manufacturer.

http://www.ta-deti.de/ta/knownproblems.html#blackbox

This guide highlights design floors with the CDI's and how to repair them.

So, as I had a new unit on the way I took the dremel to the faulty unit and quickly identified (after picking of rubber sealant under cover) a component leg with no solder.
I then resoldered the leg and tested.
Started first kick !! SUPERB

I then replaced cover and used a silicone sealant to finish the job.

I am going to keep the new unit as a spare but the bike has started and ran perfectly ever since.

So to summerize this repair technique does work if you have a little electrical knowledge and a keen eye and can save you £100.
I'd be happy to perform the repairs on your broken CDI's for a small fee also so please pm me.