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Discussion Starter #1 (Edited)
Hey guys!

I recently purchased a 1981 Hondamatic CM400E with a blown motor, was looking into buying a replacement and came across one locally.

its from a 1981 Honda CB450A, from my understanding this would drop right into my frame correct?

Just wanted some confirmation before I pulled the trigger.

Also I was a bit confused, I thought the CM400A was the Automatic transmission, Did the CM400E come with an automatic option? My title definitely says CM400E

Thanks!
 

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The CM400E is a manual transmission model, kickstart only, spoked wheels, and drum front brake. The CM400 and 450 A models have the automatic transmission, disk front brakes, electric start, and comstar wheels. Swapping an automatic engine into a manual frame is somewhat more than a simple bolt in operation.

I would suggest that you start by comparing the serial number on your title with that stamped on the identification plate on the frame neck below the handlebars.

Welcome to the group.

Got pictures?:p
 

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Discussion Starter #3
Yeah I only paid $75 for it so I didnt really look too much into what it was before handing over the money, I'm pretty sure he advertised it as a Hondamatic but its definitely a manual. VIN Numbers match, its a CM400E. It was pretty stripped down when he dropped it off (no handlebars) so I guess I took it for granted that it was an automatic haha. I guess that changes what I'm looking for!

Im excited to rebuild it regardless, so as far as motor replacements what am I able to use as a replacement aside from the obvious CM400E engine? I'm assuming any 80-81 CB/CM 400/450 manual transmission engine will be compatible?
 

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You can use CM400/450 engines from 78 to 85 at least. Although , there is some changes to make it completely compatible wiring wise. For the most part direct swap.
 

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1981 cm400a

Was wondering since I seen that someone said the engines are swappable from 78 to 85 I have a 81 cm400a and was wondering if I could swap the engine out for a 78 cm750a and without having issues?
 

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Sensei
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NO...... That would be 400/450 engines, NOT 750's....
I'm only familiar with the CB750A in '78......Where did you come across a CM version?...Or was that a Typo?
 
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