Aye Reborntoride,
I see you have posted another thread, but I shall keep putting this new info here, so as to keep it all together!
If you go to the URL link I have pasted to below, it will take you to the Yamaha OEM Parts, Motorcycle Parts site. When prompted at 'Step 1' select = Motorcycle, 'Step 2' select = TT600S, 'Step 3' = 1986. This brings up the complete spare parts list for your TT600S 1986 motorcycle/engine. (Only built between 1985-86, last year of production.)
Then go to the 'lefthand' side of the page and select 'Electrical 1', this is the parts list and diagram for the ignition system for your motor (as you have described it).
The part number appears to be: CDI unit assembly - 55U-85540-51-00
TT600S_1985-86_spares_listAlso if you don't have it, get yourself a copy of the Clymer Manual 'Yamaha XT600 & TT600 - 1983 - 1989, Ref. No. M416, ISBN 0-89287-546-1. The latter reference number, will enable any library or Amazon to get you the manual, it refers to the TT600S in detail.
I hope this little lot helps you sort things out. Go to your Yamaha dealer as they may be able to source the parts. Maybe take a few nuggets or opals along to pay for it though!

My regards, Bill.