The CT90 models have undergone several iterations of carburetor styles and jetting. Whether it was due to changes in air filter design, carburetor castings, or some unknown factor, these are the jet sizes to the best of our knowledge:
CT90 K0 (Before frame sn. 000001A)
Main Jet: #72
Idle Jet (Pilot Jet): #40
CT90 K0 (After frame sn. 000001A)
Main Jet: #80
Idle Jet (Pilot Jet): #38
K1 - K7
Main Jet: #62, #65
Idle Jet (Pilot Jet): #35
1977 (K8)
Main Jet: #62
Idle Jet (Pilot Jet): #35
CT90 '78 - '79 round float bowl carburetor
Main Jet: #65, #60(high altitude spec for above 5,000 ft.)
Idle Jet (Pilot Jet): #38