Topic: CM 400/450

[Ecosse]

Please be gentle. I have a pal with a couple of 80's CM's in his collection. Just outta curiosity I wonder if anyone knows anything about these. The engines primarily. I have the feeling they're not related to anything preceding them but don't know if they share anything with their contemporaries or if they have any attractive engineering features or if they're suitable for souping up.

I don't know nothin' except my pal's seems to go right along. No hot rod but not really a slug either.



Not my friend's but this is what they look like. 

[Grizzly]

I think i'm write in saying the motors are the same as or derived from the 400 SuperDreams and later CB450.

I can't remember these bike's having many faults with the motor's. A couple of friends I had with 400 SuperDreams used to thrash their's all over the place with no ill effect.

Don't know of any that have been souped up. Though I have read somewhere of a guy is looking to turn his into a cafe.

If your pal is not a hard rider then the chances are his bikes will go on for ever.

[HavocTurbo]

I've got one bill....

Carbs are it's weak point. Exhaust is a close second.

What really wakes this motor up is head work followed by a good set of custom filed rings.

Haven't bored mine..... yet.

She'll run with 600's all day long and not break a sweat.

But cars..... they can be detrimental to it's health.  long story.

[Ecosse]

sometimes i think about talking my friend out of the 400 mill from his parts bike so i can chuck it onto a go cart. alas... the pipe dreams never cease.

i dunno why but i'm particularly curious about these motors. maybe a good long ride on my sohc/4 will cure me.

thanks for the info havoc.

[crazypj]

3 valves per cyl, two intake one Ex.
 Head can be removed in frame which has through holes to allow the bolts to be torqued or loosened.
Dual balancers with a long chain resting on crank sprocket. Early motors needed clutch cover removed to service/adjust chain service because adjustment was off from factory and it didn't have adjuster plug (the later ones needed adjuster re-set on first service)
 I liked the carbs because they didn't have diaphragms, the pistons can get corroded though and stick if they don't get used.
Metal polish fixes them pretty easy.
 Very few problems with them, 1979/80 had generator problem where low speed trigger failed so bike wouldn't start.
 Biggest problem was exhaust balancer/silencer which rotted out real quick (usually about 18months) a piece of 3"x1.5" steel box section and some exhaust tubing repairs that pretty quick and gives a little more noise.
 Rectifier/regulator is awesome, fitted them to just about any bike with a permanent magnet alternator, seen 24amps @14volts running through one without a problem ( at least for a while  )
 PJ

[Ecosse]

awesome crazypj, thanks. it looks like the 400 didn't have what i assume is an oil cooler but his 450 looks to have one. also, 450 has air forks and... disc over drum in front?

yeah his exhaust is looking a bit iffy but he's had one 450 for a while. the parts 400 came with a black 2 into one header and muffler- mac maybe, in pretty good shape. i advised him to pull it as the 400 will likely just rot out in his yard.

so it's safe to say these are kind of orphan engines?

[crazypj]

Yep, they are pretty much out there all alone.
 There was a 350 which used almost the same engine and a Ducati sytle frame ( I think it was out well before the Duc?)
The automatics had an oil cooler, I just cant remember if they all did, been too long since I worked on them (1979)
 It sounds like you have the inside out disc brakes. Works like the Buell rim brake but smaller diameter to enable it to be covered up
They are a lot of 'fun' to work on.
 The stainless steel 'bearings' (shims) corrode onto the alloy bosses on wheel and prevent rotor from floating so brake locks up. (usually it sticks a bit) Copperslip on all the sliding parts after you clean them up works ok for a year or two (when they were used daily in all weathers)
PJ

[BlindJoe]

The ports are alot cleaner compared to the fours.

[HavocTurbo]

The ports are alot cleaner compared to the fours.

Like I said.... head work really opens these up. There's a limit, but it's a lot easier to smooth the rough edges out on these. I had to experiment with pipe size, but settled on 1-3/4" beveled out to 2" just below the crankcase.

I'm currently looking for a larger valve that will easier facilitate a bore "kit".

[Ecosse]

if you do, or have done, anything of note to your cm havoc i'd be interested to see (or hear, read) your progress.

just being nosy again.

[bryanj]

In UK we had a 250cc version and when generators start playing up holed pistons can occur

[Geeto67]

i have had a few of these over the years and my opinion will probably differ from a most of the other guys here...they are stone reliable dogs. It is a honda so of course it will be reliable but really there are so many other motorcycles out there that give a better riding expirence that it is probably best to pass on these and find something cooler.

[HavocTurbo]

i have had a few of these over the years and my opinion will probably differ from a most of the other guys here...they are stone reliable dogs. It is a honda so of course it will be reliable but really there are so many other motorcycles out there that give a better riding expirence that it is probably best to pass on these and find something cooler.

While I don't disagree, most people do what they can afford. I know I have. The CM's are dogs I won't deny. But modding them is just as cheap if you already own one or it's all that's in your price range.

I think I only spent around $600 total for mine. Now if we were counting time spent it'd be more but eh...

if you do, or have done, anything of note to your cm havoc i'd be interested to see (or hear, read) your progress.

just being nosy again.

Ask away Bill. All I really did was clean everything up. Lapped the valves, smoothed the ports and chambers. Bought some over sized rings and filed them down. Cannot remember part numbers but I'm sure if I looked "real hard"  I could find you something.

As for valves and pistons go, I haven't even started on those. Still looking into my options as far as sizes go.

I'm the kind of wrench that cannot let anything sit original. Except for my 48. I'm scared of touching that death trap.

[Ecosse]

The CM might be a dog compared to the mighty CB but with my 150(?) lb. friend on it seemed to be able to keep up. He's got one of those 10 speed 900's in his garage I keep buggin' him to get going (gummed carbs). He does a bunch of riding out to the Boston area and figure it would make a great highway bike.

Don't go digging for info on your CM Havoc on my account. My bud sure isn't interested... and I'm just a curious sort.

That came out wrong.

[HavocTurbo]

The CM might be a dog compared to the mighty CB but with my 150(?) lb. friend on it seemed to be able to keep up. He's got one of those 10 speed 900's in his garage I keep buggin' him to get going (gummed carbs). He does a bunch of riding out to the Boston area and figure it would make a great highway bike.

Don't go digging for info on your CM Havoc on my account. My bud sure isn't interested... and I'm just a curious sort.

That came out wrong.

LOL - Well I'm 250+ and can keep up with KZ650's all day long. They aren't a bad motor.... just overlooked due to inital shortcomings. They can be hopped up just like anything else. Only these are harder and take longer to find parts.

Don't think that asking questions should be limited to topics at hand either. I'm young, but I'm also experienced by LOTS of failures. The pleasures of having a mechanic for a grandfather were I got to make and break a lot of stuff on the track, strip, street.

[Ecosse]

Luck you. I'm the only gearhead in my whole family. Don't know where that gene came from!

My mom told a story about when I was an infant my dad went out and bought a red TR-4... as the family car. Mom was not pleased. Dad had great taste if bad judgment.

Another time he attempted to find out why the Chevy family car was running poorly. Mom says the driveway had parts scattered all over the place and now he couldn't get the car to run.

[HavocTurbo]

TR-4 SWEET!!!!

I have a 75 1300 Spitfire!

Trust me... replacing everything goes a LONG way!!

[Ecosse]

A buddy of mine use to race a Spitfire.  Forgot what class though. I do remember something about it having the stronger (?) rear end bit outta GT6. It was already a dedicated racer when he got it but he went all through it and was very nice when done. He's the meticulous sort.

[HavocTurbo]

I'm working on grafting a vette IRS to mine. Everyone says they are kinda straight forward..... yea... right....

[Ecosse]

I'm working on grafting a vette IRS to mine. Everyone says they are kinda straight forward..... yea... right....

Oh yeah that. It's a direct swap from what I hear. Completely interchangeable, yup.

That same friend had a 240Z with a narrowed... I wanna say 12 bolt, and a small block Chev and four speed. Almost bought that.

[crazypj]

I'm working on grafting a vette IRS to mine. Everyone says they are kinda straight forward..... yea... right....

 I think  Jag IRS would be easier (although its also heavier)
PJ

[HavocTurbo]

I'm working on grafting a vette IRS to mine. Everyone says they are kinda straight forward..... yea... right....

 I think  Jag IRS would be easier (although its also heavier)
PJ

They are... but parts are harder to find. Heavier too.

I am using the vette rear because shocks are easier to mount and coilovers (another option) are better than the transverse leaf in my opinion. lol.

[Peterbylt]

I have a 79 CM400A, one of the automatic versions.
This is just about the slowest bike I have ever ridden. It will do 70 mph but takes a while to get there.
It is also about the most reliable bike I have ever ridden. I mainly use it to comute to work and back.
The automatic is good if I get stuck in bumper to bumper which i do about half the time.
It is very comfortable to ride and gets 50 to 60 mpg.
It came with full saddlebags and faring and looks like a little wing.
If your looking to go fast its not the bike for you but if you want comfort and reliability then this is the bike.



Peter

[Ecosse]

Gotta say I actually think those bags look good on the CM! Sitting on my friends it feels a bit cramped but it does have a comfortable seating arrangement.

Looks like the little brother to his 900 10 speed. Have to start another thread about those too. I kinda want his; I like odd stuff.

That CM400A looks good in red BTW.

[Johnie]

Peter...I like your CM400A.  Looks nice and like the colors.  Here are a couple pics of what my son and I restored a couple years ago.  A 1980 CM400E and a 1981 CM400C.  Both engines run extremely well.  We wanted to keep all the OEM parts on and were able to locate OEM mufflers too.  I agree they are not a fast bike if you are into getting from here to there with no care as to what is between here to there.  We like to ride them on the back county roads around 40 - 50 MPH.  Click on the pic to enlarge.