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Discussion Starter · #1 · (Edited)
I have followed all FSM and forum instructions/tips on trying to tighten the balancer chain on my 1980 CM400E (at 10k miles and looking like it was never adjusted). No amount/direction of movement of the stopper plate appears to have any effect the tension on my chain; it remains noticeably slack, despite otherwise appearing in good order.

I have a couple of questions:

1. Is it a likely possibility that the chain slipper is stuck and cannot increase tension?

2. If the balancer chain does, in fact, need to be replaced, does the block have to be dropped and split, or can it be done in place? (I’ve tried searching the forum and web for information on how to replace the balancer chain but have been unable locate anything pertinent.

TIA
 

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So much easier to answer your questions correctly IF we know what bike you are working on........:mad:
 
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You are obviously in need of a legitimate factory service manual.

PM sent.
 

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Discussion Starter · #6 ·
You are obviously in need of a legitimate factory service manual.

PM sent.
I have been able to access LDR’s stash for some time. [1000 thanks for his generosity.] However, I am unable to find anything specifically about replacing a balancer chain. I have gone through the adjustment sequence per the Honda Factory Service Manual. The closest reference that hints at an answer is this quote from the Clymer manual:

“CRANK CASE AND BALANCER SYSTEM - Service to the lower end requires that the crankcase be removed from the motorcycle frame.”

Is this the answer? I would rather avoid tearing apart the motor at the beginning of the summer riding season in New England, if there is some other way to more simply replace just the chain.

Simply put:

Do I have to pull apart my motor to remedy my slack balancer chain?
 

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You will have to remove the motor and split the cases and remove the crank shaft to replace the chain. If you do this pick up a pair of solid balencers to replace the ones with the rubber inserts. You will have to refer to the full service manual to set the timing on the balancer.

Bill
 

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Factory service manual (NOT CLYMER)

Removal procedure on page 10-3, installation procedure on page 10-15.
 

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Discussion Starter · #9 ·
You will have to remove the motor and split the cases and remove the crank shaft to replace the chain. If you do this pick up a pair of solid balencers to replace the ones with the rubber inserts. You will have to refer to the full service manual to set the timing on the balancer.

Bill
Thanks Bill,

I was surprised to find cm450 solid balancers available inexpensively on eBay. I usually just try to things once and right, but money is tight right now. I was wondering if people thought it was worth getting a new balancer chain from David Silver Spares (around $50, shipped), or whether It would suitable to buy a used complete balancer assembly (under $50) and just install the used components. Good idea or bad idea?


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if you can find a good used chain and solid blancers by all means do so but dont do anything till you get it apart. you wont know the condition of the shafts and slippers till you can see them. It may not be the chain. if the slippers are worn out it could give you a loose chain. Have you noticed any rubber bits in your oil? Anyway see what you need first before spending any money. Since your going to have it down you might as well check the bores and rings maybe do a leak test on the valves. New gaskets and seals.

Bill
 

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Just had another thought. be careful how you handle the crank. there is a code number on it that helps identify the crank brgs if ever needed and it is hard to see to start with and if you wipe the crank down it could be removed. Dont ask me how I know this.

Bill
 

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Discussion Starter · #13 · (Edited)
if you can find a good used chain and solid blancers by all means do so but dont do anything till you get it apart. you wont know the condition of the shafts and slippers till you can see them. It may not be the chain. if the slippers are worn out it could give you a loose chain. Have you noticed any rubber bits in your oil? Anyway see what you need first before spending any money. Since your going to have it down you might as well check the bores and rings maybe do a leak test on the valves. New gaskets and seals.

Bill
Solid Advice!

There are several offerings in EBay of full (cm450) balancer sets for the same price as solid balancer alone. I’m going to get one of the full sets then dive into the motor. With any luck, I won’t need a new chain also.


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Discussion Starter · #14 ·
Maybe I should have asked this first:

How much play is there in a properly-adjusted balancer chain? Should it be taught or a little slack?
 

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I just did the complete balancer swap roughly 1 month ago, and from what I deduced from the FSM I think the chain should be as tight as it gets when loosening the nut - the spring should tighten it to the right point...however I (as many others before me) noticed that the adjustment mechanism wasn't really going anywhere, so I ended up wiggling it a bit by hand and by feeling...from what I read, if the balancer chain whines after adjusting it it means it's too tight...I actually think I'll need to re-check the slack now because after using it for 1 month it kinda feels like it loosened up a bit...
 

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On a CM400T:
My balancer chain had a little slack and I had to reposition the stopper plate to get it tight. When you losen the nuts or in my case remove the stopper plate the chain should tighten itself. I put the stopper plate back in a new position and could also see the chain get tight and lose when I moved the stopper plate left and right. The position of the dot (like a punch mark) tells if the chain is too lose and has to be replaced. It's all in the Honda shop manual.

As I remember it the chain should not be lose but when it tightens itself it's not super tight. I could make it slightly more tight by moving the stopper plate but I didn't lock the nuts in that tighter position. If I would have to tighten it by hand I would just move it untill there is no slack without using much force, however you might want to find out if something has to be replaced.
 

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https://images.cmsnl.com/img/partslists/honda-cm400e-1980-a-usa-balancer_bighu0218e7a15_5a5b.gif

10k miles?

You are aware of the significance of the DOT on the end of the balance shaft, the eccentric etc..?

Be aware of the 4 inner head bolts and their possible problems, do some research on that before you start. Yopu are aware of the 2 special tools needed for the flywheel extraction and clutch basket "nut"?

Use the gearbox and back brake to lock the engine to undo the flywheel bolt and clutch basket nut, or make holding tools for same.

From memory you do not have to remove the camshaft and head bolts to replace the balance chain, and be aware that the balance chain is roller less, with the solid chain rollers wearing quite badly sometimes. Good honda design.
 

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Discussion Starter · #18 ·
Thanks guys.

I have carefully read sections 5-9 of the Honda FSM maybe 15 times and being 10 bolts away from dropping the motor, it just occurred to me (after seeing another CM400 Balancer chain) that maybe “tighten” does not mean to a point of zero looseness. Are we, for comparison , talking about the tightness of the drive chain, balancer chain or other example...?
 

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Well, something is wrong since as you say movement of the stopper plate does not affect the tightness of the balancer chain if you're looking at the right chain. You have to look inside the engine, you barely see it.

The punch mark shouldn't cross the red line. You might have to reposition the stopper plate, just remove it and put it back in another position. As I remember it, look close somewhere around the yellow ring for the balancer chain/tensioner. If you by hand pull the stopper plate to the right you should see and feel it get tight, however as you know if everything is correct it should tighten by itself.
You can see in the photo that my stopper plate had to be repositioned since there was no more room left. This is all I know about it, good luck.

BCA2.jpg
 

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On my 400 A when I replaced the the slippers and chain I noticed that when loosening the bolt the adjustment didnt move and I had to turn several times to get it loose enough for the spring to pull the chain tight. I had the bike down so I remove the parts and dressed them off to smooth them up. As for the adjustment ancientdad told me to trust the spring.

Bill
 
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