yz 100 ignition

[Nipper]

I have a yz 100 1980 model, there seems to be a problem with the cdi. an onyone tell me if I can use either a 125 cdi or even a yz 80 cdi of the same year ? Thanks.

[vandy010]

if its just the CDI box, i've had success before mixing and matching Yamaha CDI's, as long as they have the same number and colours of wires you'd be fairly safe i reckon.
someone else may correct me though...

[OverTheHill]

agree with vandy010, pretty safe mix & matching so far as colors are the same. but in saying that, the most likely thing would be the energising [source coil] down the bottom. [been 30 odd years but] if it has the gray plastic encapsed two coils then main one should read something like 1400 ohms give or take. Might be wrong but is a hell of a high number compared to what i call an ordinary cdi coil of around 350 ohms. [might be 1700 ohms] pay to find out from someone with a spec sheet. Can't recall the reading for the other coil but is low ohms compared to other one. Has wire as fine as 'hair' in it [if i had hair]. Think color of wires is 'brown to black' for test, other is 'red to black i'd think. If i can find an old spec sheet i'll get back. In saying that--if it's definitely the cdi box--well sorry about rambling on. Plus make sure all connector plugs are making contact. Good luck.
ps, i'm relating back to my 125G 1980 but should be relevant except the 100 might have had mag on the left as opposed to right on the 125 from 1980. Someone will tell me if i'm wrong. All good.

[Nipper]

Cheers Vandy and over the hill . I will check the coils and see if they are around the mark. If they open circuit or faulty for whatever reason are other coils interchangable.e.g yz 80 or yz 125 ? Thanks.

[OverTheHill]

i'd say 125 coils would be same without really knowing. if they look the same type & screw holes line up, should be ok. in saying that, if mags on the left on the 100 as opposed to 125g being first model on right--does that mean anything so far as how things are wound==[dunno sorry]. Be interested to know the outcome in the end. Just thinking a "79 F 125 was left side mag, check part numbers between the two models although that's not always the answer as sometimes numbers change for very minor reasons & will still work ok. Cheers.