Fitting another motor in a CB400T frame

[Blueofnoon]

So I got a '78 400T Frame and am starting my first ever build. I am having trouble finding the proper motor to go in it and was wondering if much modification, if any, would be needed if I attempted to put a CB350 or CB750 motor instead? I appreciate any help!

 

[CALfeRacer]

The 400T motor is a stressed member of the frame in your bike. CB750 and 350 motors are not. 350 wouldn't be terrible to mount, but you would probably have to make a set of lower frame rails going from the end of the current front tube to the rear of the frame. CB750 would be the same, but you have the issue of it being much wider than the 400T engine. Also, the backbone on the frame could give you issues with clearance for carbs if you're swapping another engine in.
If it were me, I'd look for a CM400 or CM450 motor to go in, they're basically the same with the exception of the 450 motors having an oil cooler on the front. Shouldn't be any trouble to get one in your frame though, they're mounted the same.
What parts do you need? I have a complete motor from a 78 CB400T.

 

[Blueofnoon]

That's what I was afraid of. I appreciate the help! I am just looking for a 78 CB400T Motor that is in decent shape. Preferably running or one that wont take a whole lot to get running.

 

[CALfeRacer]

Where are you located? I am selling mine along with some other parts, if you're interested. Motor is complete but a bit dirty, and the top end looks good. Kicks over free, but there is some surface rust on the flywheel.

 

[Blueofnoon]

Sounds very interesting! Although I am all the way in Massachusetts! I have a feeling that would be pricey shipping bill lol

 

[CALfeRacer]

Shoot. Yeah, it would probably be a bit expensive, and I'd need do build an engine crate.. Good luck with the search though!

 

[VonYinzer]

Don't forget the CM450. I believe it shares a frame w the 400.