Honda Twins banner

1 - 20 of 24 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter · #1 ·
So, I recently came into possession of a 1978 Honda CM400A Hondamatic. I got the bike in a trade ( i Traded a T-Top '92 Camaro RS for it) and upon it seemed the bike looked a little rough, but was otherwise all there. I took it knowing it was non-running, but i was entertaining the idea of a cool old-school bobber project anyways, so i wasn't like crazy concerned due to the fact that I've heard these bikes are RELATIVELY simple to work on and maintain. I had to go to work right after we made the trade, so unfortunately i did not have time to dig in and investigate what was REALLY up with the bike. So, i get off of work at around 8:30, go home, and upon closer inspection i find that when i hit the kickstart - nothing. No popping, no compression, NOTHING. Just a whirring noise from the rotating assembly rotating in the crankcase. i pop the valve cover, just to realize that THE LIFTERS AREN'T EVEN SECURED TO THE TOP OF THE MOTOR (there were no bolts in the lifter racks whatsoever!), so when i'm hitting the kickstarter the camshaft is forcing the lifters to jump up off the valves, thus i'm going to assume that is the source of my compression problem (correct me if i am wrong.). I put power to the bike - nothing. Then, i realize that the fusebox is devoid of any fuses to speak of, so i caught a ride to Advance, and bought a 15A and two 7.5A fuses for the main box. Upon returning home i was able to get power to the instrument cluster, and all of the lights come on, minus the turn signals - but when i hit the electric start it does nothing but dim the head & tail lights. This is all very new to me, if any one can shed any light on how to move forward and where to start, i would appreciate it enormously. i included some pics below, i will take pics of the strange state i found the valves in when i get home.
Cheers!
-JB
 

Attachments

·
Premium Member
Joined
·
10,203 Posts
I bet it ran when he parked it though!:-?

I'll be interested to see the camshaft pictures, sounds mighty strange.

When you press the start button it should disconnect power from the headlight and connect power to the start solenoid. A test light or multimeter can tell you if this much is working. I suspect you are not getting power either to or through the solenoid.
 

·
Registered
Joined
·
111 Posts
When using the kickstart make sure the bikes in true neutral. The autos can be a little odd finding that position and the kickstart wont work in that case
 

·
Premium Member
Joined
·
24,208 Posts
No bolts in the rocker stands means the head bolts are missing, maybe you got a box of spare parts with the bike and they're hiding in the box. A couple of ways to proceed there. 1) do a quick rebuild of the top end (rings, valve clean up, fresh gaskets) and proceed with the project. 2) install the head bolts and torque then pray you've got decent compression. I'd opt for #1 since you'll be able to inspect and repair/replace any bad top end pieces.
You will want the FSM. PM sent
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #5 ·
Awesome!

Thanks! I will definitely research through the FSM's, that will be of great assistance. Here is a photo of what i found when i pulled the valve cover, as per the request to see what the cam area looked like. It was not even attached and it had absolutely no valve cover gasket to speak of. I happened to be shirtless when i was playing with it earlier, and realized that when i manually turned the kickstarter that i could feel a soft whooshing of air out of the gasket between the head and the block. (photos below.) Any further advice is greatly appreciated as this is my very first vintage Honda.
Cheers!
-JB
 

Attachments

·
Registered
Joined
·
1,574 Posts
Wow your missing a whole lot more than the head bolts .The full service manual will show you what you will need. I vote with LDR .Take the two bolts off the sprocket and slip,the chain and sprocket off and remove the cam. Tie off the chain so it wont fall into the motor and pull the cylinder head and head off. Then follow the manual for the rebuild.

Bill
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #7 ·
Well upon further inspection I found the cam chain to have these little pieces of the chain sticking up - not entirely sure what they are. Have been researching the FSM all day. Ordering a whole gasket kit off of eBay, as well as a head bolts kit. Gonna run me about $86.99 for both, but most friends I have asked who know anything about these bikes have told me the bottom end is pretty much solid as a rock to just build the top end first and leave the pistons and crank alone. Any further advice, as always, is greatly appreciated.
Cheers!
JB


Sent from my moto g(6) play using Tapatalk
 

·
Registered
Joined
·
13,085 Posts
Looks like you need a cam chain too - those seem to be inner plates of the link section, it appears to only have one full plate connected in that section. I wouldn't trust it to start it, much less ride it
 

·
Registered
Joined
·
2,475 Posts
I hate to say this, but you got taken! If I were you and set on getting this bike going, I would get another bike, or at least another engine.
TOOLS
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #10 ·
I hate to say this, but you got taken! If I were you and set on getting this bike going, I would get another bike, or at least another engine.
TOOLS
So... It's not as simple as just replacing the cam chain?

Sent from my moto g(6) play using Tapatalk
 

·
Registered
Joined
·
2,475 Posts
You have a lot of missing parts that are going to be hard to find and with the damage to the cam chain, it is hard telling what else that engine has suffered. I would bet that there are a few stripped out holes in the case where the head bolts thread into.
TOOLS
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #12 ·
You have a lot of missing parts that are going to be hard to find and with the damage to the cam chain, it is hard telling what else that engine has suffered. I would bet that there are a few stripped out holes in the case where the head bolts thread into.
TOOLS
Ooof. That sounds painful. So would my best bet be to just buy a new motor?

Sent from my moto g(6) play using Tapatalk
 

·
Registered
Joined
·
1,574 Posts
The timing chain is one piece so you have to pull the crank to replace it. Tools is right you dont know what you are going to find.IMHO I would strip the motor and find out what you need then decide what to do. I may be able to help you with 95% of what you need for the top end but you need to see what the bottom end looks like.

It doesnt cost anything too look. Let us know what you find. Or dont find.

BIll
 

·
Registered
Joined
·
154 Posts
Just for info Knauff13 has a 1978 cb 400A non running motor for sale. A lot of those parts will interchange.

Bill
Hey! I was just reading through this because I like learning about issues with 400As, and my own name popped up!

So, here's the deal. Obviously, it would cost an arm and a leg to ship a whole motor to Florida. BUT I already have the engine off the frame and have no use for it, so it would be (relatively, and with precise guidance for what you need) easy to take the top cover off and pull out a part or two. I had it open briefly a few months ago and what I saw looked clean. If you're set on getting it running, that is.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #16 ·
Hey! I was just reading through this because I like learning about issues with 400As, and my own name popped up!

So, here's the deal. Obviously, it would cost an arm and a leg to ship a whole motor to Florida. BUT I already have the engine off the frame and have no use for it, so it would be (relatively, and with precise guidance for what you need) easy to take the top cover off and pull out a part or two. I had it open briefly a few months ago and what I saw looked clean. If you're set on getting it running, that is.
Well I was decoding the VIN - it comes back as a 1978 CB400A (VIN: CB400A-2006616) SO THAT MOTOR is a perfect fit.

Sent from my moto g(6) play using Tapatalk
 

·
Registered
Joined
·
154 Posts
Well I was decoding the VIN - it comes back as a 1978 CB400A (VIN: CB400A-2006616) SO THAT MOTOR is a perfect fit.

Sent from my moto g(6) play using Tapatalk
Great. Let me know what you want to do. If you PM me, I'll give you my email address, which I check more frequently than the board, although I try to hop on every day or two. It might be helpful for others here to help us identify exactly what you'll need, unless you think it's somehow feasible to get the entire motor from PA to Fl (I think it's about 150 lbs...). If anything takes a special tool, it might take a little extra time and patience. I have a socket wrench set and a couple JIS screwdriver heads... that's about it! I'm really good at hitting things with a hammer though.
 

·
Registered
Joined
·
1,574 Posts
Just for info the cheapest way to ship is Greyhound . 100lb limit so two packages. I had a price of $50.00 to ship a complete ca160 motor from Florida to Ohio.

Bill
 

·
Registered
Joined
·
154 Posts
Just for info the cheapest way to ship is Greyhound . 100lb limit so two packages. I had a price of $50.00 to ship a complete ca160 motor from Florida to Ohio.

Bill
Greyhound is potentially feasible on my end, as long as there is no hurry in getting the motor packed into 50 lb (edit: 100 lb) portions and finding a day when I can swing by the bus depot. It seems like an awful lot of meat to ship to replace whats missing on the top end, but then again, maybe he'll need it based on what he's seen so far.
 

·
Registered
Joined
·
1,574 Posts
The USPS has fixed price boxes and will ship what ever you can stuff in it. I have everything he needs for the top end and would have offered it to him but thought your motor might be better as Im working on an 400a now. I was thinking of the whole motor but if he can identify what he needs the fixed priced boxes are the way to go.


Bill


Note to hondabobber400. if you pull the crank be careful of wiping the numbers that are painted on the crank . They are part of the code for ordering crank brg and they are hard to see at best. Not saying you need brgs but just be careful not to wipe off the numbers.
 
1 - 20 of 24 Posts
Top