Yamaha TT-R90P Manuel D'atelier Du Proprietaire page 274

IGNITION SYSTEM
2. Inspect:
Source coil resistance
Out of specification → Replace.
Tester (+) lead → Brown lead 1
Tester (–) lead → Green lead 2
Source coil
resistance
688 ~ 1,032 Ω
at 20 ˚C (68 ˚F)
6 - 5
– +
ELEC
Tester selector
position
Ω × 100