Author Topic: CB400T engine, what frames will fit? (Read 18468 times)

Alan F. · « **on:** August 23, 2009, 05:11:28 PM »

I just scored a CB400t engine from feebay for a side project, I'm wondering what frames it's compatible with? This is the single cam twin, 5-speed with a kickstart and chain drive, and it's got header pipes and carbs, in 2 other auctions I scored some decent directionals and the tach, and the entire electrical system from the donor bike. I'm thinking of a sporty low-buck lightweight bobber. CB400t, cm400 cmx? cb450sc? Does anyone know? I think it's a 78 model CB-400TE 4052479
-Alan

Pinhead · « **Reply #1 on:** August 25, 2009, 02:58:46 PM »

Is the CB400t engine the same as the CM400?

tbpmusic · « **Reply #2 on:** August 25, 2009, 03:28:19 PM »

I think it will pretty much fit in any 400/450 models that use the engine as part of the frame (like the old 305 SuperHawk).......

jeepurz · « **Reply #3 on:** August 25, 2009, 04:24:14 PM »

purty much what bill says above, ive never tried the 450 personally but cb cm, A and T should be for sure.
frame shown is 78.

Pinhead · « **Reply #4 on:** August 25, 2009, 04:33:37 PM »

Now THAT's interesting, a monoshock CM400... Are you planning on racing? Is the frame stiff enough for the rigors of tight cornering at high speed?

EDIT: I guess the frame on the bench is the same in the first pic so I guess it's not for racing.

How is the frame stiffness, anyway? Seems flexy compared to my '79 CB650...

jeepurz · « **Reply #5 on:** August 25, 2009, 05:47:15 PM »

frames are purty much rubber without the motor in em.

Alan F. · « **Reply #6 on:** August 25, 2009, 07:51:32 PM »

Quote from: Pinhead on August 25, 2009, 02:58:46 PM

Is the CB400t engine the same as the CM400?

I think the cases are different somehow, but I'm not sure. I'll have to look up the front mount and it's bolt sizes and the rear mount bolts sizes, maybe they'll be the same between all of the bikes you guys called out?
Wish me luck.

jeepurz · « **Reply #7 on:** August 26, 2009, 05:37:39 AM »

if you need pics yell, ive got both engines somewhere in a pile O parts.

Alan F. · « **Reply #8 on:** August 26, 2009, 02:37:27 PM »

Just as you we suspected, I compared the CM400C/CM400A from 79-82 with the CB400TI and TII from 78-79, and every motor mount bolt is identical, and the front mount is even the same part number.

Alan F. · « **Reply #9 on:** August 26, 2009, 02:51:04 PM »

CM450A/E 82-83 and CM450C 83 are mostly the same too the front mount bolts have been changed from 8x80 to 10x80, this should not be an issue.

The CMX models had twin downtubes on the 450 and a single downtube for the 250, they may work...may not.
The CB250 Nighthawk frames are the correct type, but the bolt sizes are too different to say it's a match, these may or may not work.

Alan F. · « **Reply #10 on:** August 26, 2009, 02:57:56 PM »

Quote from: jeepurz on August 26, 2009, 05:37:39 AM

if you need pics yell, ive got both engines somewhere in a pile O parts.

Thanks man, pics might add something to this thread, but if it's a hassle skip it.
-Alan

crazypj · « **Reply #11 on:** August 26, 2009, 05:39:13 PM »

As far as I know 450 and 400 are pretty much identical.
450 is 5mm bigger bore than 400

PJ

jeepurz · « **Reply #12 on:** August 30, 2009, 03:22:27 PM »

[/quote]

Thanks man, pics might add something to this thread, but if it's a hassle skip it.
-Alan
[/quote]

Ok , the pics of the polished cases are 78cb 400 T for sure it has kicker hole,

these pics Im unsure of year , if its cm or cb, but note lack of kicker hole (im hoping my polished cases will fit and I can fit a kicker to this block.
other than thats its identical , engine # written on case

last is the automatic, rite side is for sure dif, left is not , # is written on block.

las

jeepurz · « **Reply #13 on:** August 30, 2009, 03:24:23 PM »

forgot to add all mounting points are the same.

Alan F. · « **Reply #14 on:** August 30, 2009, 05:46:05 PM »

Very, very cool polished cases, they look great. I've just picked up a CM400C partsbike, Looks like I've found a winner.
-Alan

crazypj · « **Reply #15 on:** August 30, 2009, 07:09:43 PM »

The polished covers are from early motor, have to remove clutch cover to adjust balancer chain.
Usually have to re-set adjuster quadrant after 500 miles if new balancer chain is fitted.

PJ

Alan F. · « **Reply #16 on:** August 30, 2009, 09:19:52 PM »

Cool PJ, thanks. I've got a thread going at the twins forum, the .com one...
Jst look for 'the 99 cent special'

Pinhead · « **Reply #17 on:** August 30, 2009, 09:27:47 PM »

Twins forum?

Alan F. · « **Reply #18 on:** August 30, 2009, 09:35:10 PM »

www.hondatwins.com is the one I mean, Lots of members here are members there too.

there's also www.hondatwins.net which has lots of good info too.

jeepurz · « **Reply #19 on:** August 31, 2009, 05:33:18 AM »

Quote from: crazypj on August 30, 2009, 07:09:43 PM

The polished covers are from early motor, have to remove clutch cover to adjust balancer chain.
Usually have to re-set adjuster quadrant after 500 miles if new balancer chain is fitted.

PJ

pj those polished covers are the ones you helped me on the balancer chain problems, I never could figure it out, I ended up trading an ol xs motor for a newer 400 engine
(2nd set of pics), im hoping to be able to swap the kickerless parts to make it a kicker only.

crazypj · « **Reply #20 on:** August 31, 2009, 12:25:56 PM »

Hi Jeep,
I still have manual for it, bit covered in oil though

PJ

Pinhead · « **Reply #21 on:** September 07, 2009, 05:01:27 PM »

It may or may not help you, but here are a couple of pics comparing the CB400T frame to the CM400T. The CB's frame is a more solid design, IMO, than the CM.

CM400:

CB400:

Pay special attention to the rear section where the "tail" attaches to the rest of the frame. The CB's rear is much straighter and sturdier than the curved CM's frame.

Alan F. · « **Reply #22 on:** September 08, 2009, 06:23:33 AM »

That's an interesting point there, I never noticed that. Have you ridden both bikes? I'd be interested in hearing the key differences in handling.

I've picked up a complete CM400C for $40 it's very tempting to just bolt it together and ride, but I've really got to finish my 750K3 by spring.
I'll have plenty of time to think about what direction to take this project.
-Alan

Pinhead · « **Reply #23 on:** September 08, 2009, 10:09:21 AM »

I haven't ridden the CB400 but the first thing I noticed when I started riding my '79 CM400 is the instability when compared to my '79 CB650. The bike was basically unrideable above 55mph if the grab rail was removed; the rear section of the frame flexed too much to be stable. The slightest shimmy in the front-end made the entire bike feel like a slinky. Stiffening the rear section with the grab rail made the bike much more stable (though still not as good as the 650).

Alan F. · « **Reply #24 on:** September 08, 2009, 11:55:05 AM »

I don't have a grab bar for my CM, I was thinking of running a solo 'tracker' style seat without one too....
I guess some subframe reinforcements are going to be needed. I'll have to get that figured out before I design my airbox and paint everything.

I love the look of these frames without side covers, too bad they're hard to tune with pods. I'm considering an aluminum airbox that'll house the battery box and all the electrical stuff, kinda like a fake oil tank...

I think it'll allow enough vacuum as long as it's not smaller in volume than the stock airbox, and the inlet is the same size, I'll actually use the stock air filter cover which has the inlet on top.

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Author Topic: CB400T engine, what frames will fit? (Read 18468 times)