hillbilly K
New Member
I have a CM91 and a shop manual for a C90. What's the difference in the CM91 and C90?
CM91 vs C90
- Thread starter hillbilly K
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joel1234567
Active Member
I think you might be confusing the C90 with the CM90.
It is my understanding that the CM91 was the U.S. version of the C90. Same bike, but the CM91 does not have turn signals and it has a bobbed rear fender, and the C90 used a newer style front fork and the handlebars are also a different part because the speedometers have a slightly different shape, as well as the obvious mph/kph difference.
Both were the “new”(for 1966) 89cc overhead cam with aluminum head.
The CM91 still used the old style forks that were on the old 87cc iron head OHV pushrod CM90
If you’re referring to the manual in the attached picture, all of the specs and adjustments of the C90 will apply to your CM91.
Both were the “new”(for 1966) 89cc overhead cam with aluminum head.
The CM91 still used the old style forks that were on the old 87cc iron head OHV pushrod CM90
If you’re referring to the manual in the attached picture, all of the specs and adjustments of the C90 will apply to your CM91.
hillbilly K
New Member
Thanks, that is the exact manual I have. Just wish I had time to work on it now.....
This is partly incorrect: the CM90 was first 90 cc engine with a regular overhead valve design. Then came the CM 91 with the same chassis as the CM90, but with an upgraded & more powerful overhead cam engine. Then the C90 series came with redesigned forks and other slight chassis changes. It was the C50/70/90 series that continued on into the 70s and 80’s
I have a 1966 CM91A I've been working on. It has the Keihin M91A and an automatic transmission (actually a shifter lever actuated clutch).
This particular carburetor is not covered in the above mentioned manual. The published date on the front is 1977 but inside there are no references to model years. I have to wonder why they left it out and the CM91A designation on the front cover. Since this was a big change at Honda for 1966. Some models spanned years and there are at least a half dozen different carburetors. Funny how the '66 Honda Part Manual for the CM91 had the early Keihin M91A carburetor in it. I have a Honda Shop Manual, includes C90, with a 1971 Date stamped on the rear cover and there is no coverage of the push rod engine in it. I concur with "Blaine" having heard from somewhere that the C90 and CM91A are the same bike, just sold in different markets/regions.
This particular carburetor is not covered in the above mentioned manual. The published date on the front is 1977 but inside there are no references to model years. I have to wonder why they left it out and the CM91A designation on the front cover. Since this was a big change at Honda for 1966. Some models spanned years and there are at least a half dozen different carburetors. Funny how the '66 Honda Part Manual for the CM91 had the early Keihin M91A carburetor in it. I have a Honda Shop Manual, includes C90, with a 1971 Date stamped on the rear cover and there is no coverage of the push rod engine in it. I concur with "Blaine" having heard from somewhere that the C90 and CM91A are the same bike, just sold in different markets/regions.
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