Honda Twins banner
1 - 20 of 29 Posts

·
Registered
Joined
·
32 Posts
Discussion Starter · #1 ·
It has come time to adjust the balancer chain on my ‘79 CM400T. It has 17k miles and after adjusting it last year the plate came close to bottoming out on the stud. Before putting the bike away for the winter there was a bit of noise coming from this area. This is my first bike and thus my first attempt at digging into the engine. Venturing into the unknown can be quite intimidating so I figured I’d post some pics of the process to hopefully help anyone doing the same thing and to also seek your guys’ expertise.

Here's a shot of the crankcase, first thing to do is drain the oil out otherwise it would get pretty messy. I then went around and broke the bolts loose around the case.


Before completely removing all the bolts from the case, remove the kickstart arm and the footpeg.


Work your way around the case and remove each of the bolts. After the bolt by the tachometer cable is removed, the cable will slide out.


Loosen the two nuts on the clutch cable to create some slack to pull the cable off.




Once all of the bolts were removed I used a rubber mallet and carefully tapped around the crankcase to break it loose. In the end I had to resort to the putting my finger inside the oil hole and pull on the case while tapping it with the hammer.


Thankfully the punch mark was above the 3 o'clock mark so there is still life left in the chain. *large sigh of relief*


I could not manage to get the adjuster plate any higher on the shaft, but the manual states "...center it within the threaded stud." So I am guess that this is where it is supposed to be.


This is where I am at at this point. Still waiting for the gasket and oil seals to arrive. Any input, tips, corrections, advice would be appreciated. Been having a few nice days lately and I can hardly wait to get back out on the road.
 

·
Sensei
Joined
·
27,183 Posts
From your pix, there is no spring tension on the balancer shaft or its stopper plate.... I believe that to be currently (as shown) incorrect (AFAIK)..... If I remember correctly, the punch mark should be in the 6 o'clock position when the stopper plate is centered, then temporarily locked down with the 8mm nut after rotating as far as possible clockwise...(that would place the punchmark at about 8 o'clock).....
I believe you HAVE to split the lower cases to check/reset the balancer shafts and do this properly.... I also don't remember any 3 o'clock reference.....Spring goes in at 10, shaft rotated to 6, and install plate (center) and 10mm nut...Rotate CW to max and lock down with 8mm nut......Then the camchain tensioner,and rear chain guide....align the TC and TH marks...etc, etc..front chain guide, etc, etc...... then when the 8mm nut is loosened, the balancer chain will be automatically tensioned... lock 8mm nut back down to 15-18 ft/lbs....10mm nut to 22-25 ft/lbs
 

·
Premium Member
Joined
·
10,203 Posts
66Sprint said:
If I remember correctly, the punch mark should be in the 6 o'clock position when the stopper plate is centered, then temporarily locked down with the 8mm nut after rotating as far as possible clockwise...(that would place the punchmark at about 8 o'clock).....
This is the procedure if you have disassembled the engine. If you're just adjusting the tension 7_zero has it right according to the Clymer manual. Still using that since I haven't found a Honda manual for the 400 on line. Wish I could since Bills PDF of the 350 manual seems a lot better!

The directions seem a bit screwedl up since the section an installing the balancer system describes the clock positions on the shaft with the engine upside down and the adjustment procedure is described right side up. Not too sure they got everything transposed.

Anyway, according to the Book of Clymer, you're OK.
 

·
Sensei
Joined
·
27,183 Posts
Considering my reluctance to trust any "Clymer" proceedures, Please explain why an automatic tensioner has NO spring pressure (therefore NO tension)......
 

·
Premium Member
Joined
·
10,203 Posts
The spring pressure rotates the chain tensioner shaft inside the engine to take the slack out of the chain then the nut on the adjusting plate is tightened down to hold it in that position.

In 7_zero's last picture you should be able to rotate the adjusting plate against the spring pressure and it would return to its properly adjusted position. When the chain wears enough to cause the tensioner shaft to rotate to where the punch mark is below the 3 O'clock position the chain needs replacing.

I still think Clymer has that upside down/right side up and clockwise/counter clockwise stuff screwed up somehow.

I think I'll go spend some more time Googling for that Honda manual.
 

·
Premium Member
Joined
·
479 Posts


J-T I have the complete HSM covering 1978-81 CB/CM400s. I've got an auto document feed scanner at work and will get it scanned for you and fellow 400 folk. Don't exactly know where to post it but will figure that out.
 

Attachments

·
Registered
Joined
·
32 Posts
Discussion Starter · #8 ·
Awesome, thanks for your help guys! This kind of work always makes me nervous so it's good to get confirmation from those with experience.

J-T you are correct, as it sits now if I press on the adjuster plate I can see slack in the chain. As soon as pressure is let off of the plate it readjusts and the chain tightens back up. Hopefully now I'll be able to get a few thousand more miles on it before I'll have to dig into the engine as 66Sprint described.

MnBikeGuy, I'd love to get a hold of that digital version too. Once it's done please be sure to drop us all a line as that would be great!

Also, if anyone feels so inclined I could use some help with my clutch. ;) viewtopic.php?f=17&t=3269
 

·
Premium Member
Joined
·
479 Posts
7_Zero said:
MnBikeGuy, I'd love to get a hold of that digital version too. Once it's done please be sure to drop us all a line as that would be great!
Check it out at: viewtopic.php?f=20&t=3260

Happy wrenching! :)
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #11 ·
Alright.....I could use some more help.:cry: I have finally been able to get the bike back together and running. However it just doesn't sound right, and in more ways than one! There is a noise that seems 'chainy' to me, so I figured it must be the balancer chain again. I removed the adjuster plug and loosened the adjuster nut on the balancer plate to double check it and it didn't move. For the most part that is a good thing, but I decided to push on the plate with my finger. It didn't reset! If I push the plate up, it stays up. If I push the plate down, it stays down. It is kind of 'sticky', once moving it moves freely but seems to stick in the position it comes to rest at. What have I done wrong?

The other noise is like a 'clattering' sound. I adjusted the valve clearance while the bike was apart so I am wondering if it is the valves. I haven't ever adjusted valves before so it is very possible that I did it wrong. I have some audio files that you guys can listen to that will hopefully help.

The first clip is with the mic pointing straight at the engine.
Sound clip 1

This clip is with the mic pointing away from the engine, there is a little more static, but a little less harsh sound.
Sound clip 2

Thanks again for your help!
 

·
Registered
Joined
·
5 Posts
I also have an issue with adjust the balance shaft. I have the Hondamatic version and it doesn't seem I have an adjuster plug. so I assume I have to remove the side cover correct?
 

·
Premium Member
Joined
·
5,610 Posts
The balancer chain on my CB400 was the same way, it wouldn't automatically adjust when the nut was loosened like was stated in the manual. I ended up adjusting it like you did, with my finger. I didn't put it too tight but not loose. The spring on that balancer rod is very weak and I found it didn't do much. I think you'll be fine as long as its not overly tight.
 

·
Registered
Joined
·
57 Posts
I have three Honda CM400's one is a model t the other two are model a (Hondamatic)
I have tried to adjust the cam chain on two of them with little success. In fact after trying to adjust one of the A models that was fine before, now makes a loud rattling noise. So I have both Honda's making noise.

I adjusted (tightened the counter rotating shaft chain), and although in the a model it is a bit of a pain to get to, I was able to tighten the chain. So I suspect no noise coming from that part of the motor. On all three 1981 models the manuals show a stud with a "locknut" on it and it suggests to loosen off the "locknut" and then let the bike automatically adjust the chain then lock it down by tightening the lock nut. On all three of my 1981 Honda's, there is an acorn nut rather than a locknut, and none of the auto adjustments seem to work.

Can I adjust it correctly manually when i remove the valve cover? Has anyone had any success doing the adjustment this way?

If I push the stud in, does that tighten the chain? Or if i pull the stud out does that tighten the chain? I am reluctant to pull the engine apart just to learn how the damm thing is supposed to work...

Whoops this message is about the camshaft chain tensioner and not the counter rotating crankshaft balancer, although I do appreciate the knowledge that allowed me to successfully adjust that chain. Since most of you that are knowledgeable about the crankshaft chain adjustment I assume you would also know all about the camshaft chain adjustment...

Mike..

3 1981 Honda CM400
1 1979 Honda CB400
1 1980 Yamaha SR250
3 1981 Yamaha XS400 Heritage
2 1981 Yamaha XS400 Special
1 1979 Yamaha XS650 Special
1 1982 Suzuki GS400T
1 1981 Suzuki GS400L
1 1967 Norton 750 N15
1 1970 Triumph 650 Bonneville
 

·
Registered
Joined
·
28 Posts
Regarding Balancer Chain Adjustment on the Honda CM400

Which position is correct - picture A or picture B?

Per the FSM, when I loosen the 8mm through the adjuster portal cap, I get picture B - nothing happens. I can, manually maneuver the stopper plate to make it look like picture A and then tighten the adjuster nut in that position. So just want to double check which picture (position is correct). I've read through several different threads on this and I'm still confused. I really don't want to take off the right side cover and instead want to do this through the adjuster cap. Thanks in advance.


Motor vehicle Auto part Engine Automotive engine part Vehicle

Auto part Wheel Tire Automotive wheel system Disc brake

Wheel Auto part Automotive wheel system Rim Vehicle
 

·
Premium Member
Joined
·
24,208 Posts
A is correct but since your's is a B that means the adjuster will need to be reset. Sorry but the cover has to come off to do that.
 
1 - 20 of 29 Posts
Top