Author Topic: New (to me!) '77 CB400F - US model  (Read 38176 times)

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #225 on: March 01, 2019, 06:00:11 PM »
I'm ordering up some brake parts... any way to tell whether my current brake hoses are original?  Should I look for any markings in particular - or lack thereof?  End-to-end, the lower hose is 14", and the upper one is 13-1/2" ('77 US-spec with higher bars).

I'm inclined to re-use them.  They look ok - not what I'd call new, but no cracks or splits or odd bulges anywhere...

Offline hairygit

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Re: New (to me!) '77 CB400F - US model
« Reply #226 on: March 01, 2019, 06:43:56 PM »
Personally I would not use old hoses, you have no idea how old they are, they could be breaking up internally, and let's face it, replacements are relatively cheap, especially compared to wrecking your bike in the event of a sudden hose failure!

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Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #227 on: March 01, 2019, 09:22:56 PM »
Personally I would not use old hoses, you have no idea how old they are, they could be breaking up internally, and let's face it, replacements are relatively cheap, especially compared to wrecking your bike in the event of a sudden hose failure!

Here's where I'm at right now: how many parts do I replace and repairs do I make just to get the bike to the point where I can see if it works?  I want to figure out my baseline before I start dumping money into this project.

That said, however, I'm leaning toward the wisdom of your suggestion - safety should come first!  If the brake hoses were to fail when I needed them, I daresay that damaging the bike wouldn't be my top concern...

Offline Nurse Julie

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Re: New (to me!) '77 CB400F - US model
« Reply #228 on: March 01, 2019, 09:44:41 PM »
It can be a difficult decision knowing how far to go and how much money to spend on an old bike. Safety is paramount, looks and performance are at the bottom of the list. Do enough to get it starting, running and stopping. Anything else can be done later, if you decide its worth continuing with the project.
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Online Bryanj

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Re: New (to me!) '77 CB400F - US model
« Reply #229 on: March 01, 2019, 10:12:28 PM »
If there are no leaks, bulges or cracks in the outer casings of the hoses, especially at the crimp ring on the fittings, the UK safety testers manual says they are good to use and if ok by those standards i would build with what you have and possibly change later.
By the same token i will not accept ANY pitting on the caliper piston and unless i had myself fitted a new seal recently would not reuse a seal.

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #230 on: March 08, 2019, 12:46:43 AM »
The discussion about the cam chain adjuster in the 350-400 section has me wondering - I don't really understand exactly how this thing works, and I haven't run the engine yet.  is there any way to check how well the adjuster is working, if at all, without the engine running?

The shop manual just says to loosen the lock nut and tension adjusting bolt, then re-tighten both (engine running).  How much re-tightening torque are we talking about here?

Online Bryanj

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Re: New (to me!) '77 CB400F - US model
« Reply #231 on: March 08, 2019, 06:01:12 AM »
you can replace the tensioner by just removing the lower crankcase but its still an engine out job. remind me what miles your bike has on it? If you have been reading about them you now know what goes wrong with the tensioner when chain gets slack, they don't work very well as the springs loose strength but you can use the small screwdriver down the blanked off hole to see if it is moving at all.
If it was running before it will again before deciding what to do and you will not loose anything except a small amount of your time, it can always be done later just do not get disheartened.

Offline Nurse Julie

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Re: New (to me!) '77 CB400F - US model
« Reply #232 on: March 08, 2019, 08:53:27 AM »
   How much re-tightening torque are we talking about here?
There is no torque, its automatic spring tension that enables the process of adjusting the chain. You only undo the lock nut and adjuster bolt to allow free movement of the chain tensioner adjuster bar to allow the springs to push the chain tensioner adjuster bar to be pushed down further on to the horse shoe, which in turn, pushes the tensioner slipper on to the chain to take up the slack. It's an automatic tensioner. But for the process to work and remove any cam chain rattle from a slack chain, the chain must still be within service limit, the horse shoe pivot not seized and the spring not weak. As Bryan says, worry not now, sort it out at a later date if needed.
« Last Edit: March 08, 2019, 09:14:21 AM by Nurse Julie »
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
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Online K2-K6

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Re: New (to me!) '77 CB400F - US model
« Reply #233 on: March 08, 2019, 09:18:28 AM »
It maybe worth a look into Julie's engine rebuild thread to fully view the component parts and give yourself a broader picture in overview.

If you want to check if tensioner is moving on a non running engine, loosen the set/pinch bolt,  put something like a small screwdriver against the spring rod, and get someone to turn the crank anticlockwise (looking at ignition side) slowly.
This'll put the camchain into tension on the "wrong" side and should push the rod towards your hand if the pivot etc are free.

If it moves,  then turn the crank clockwise and it should go back away from you again. At this point you can lock the pinch bolt again as all the camchain slack will be placed next to the tensioner and should be adjusted and held by the tensioner.

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #234 on: March 08, 2019, 05:09:05 PM »
Thanks guys...

you can replace the tensioner by just removing the lower crankcase but its still an engine out job. remind me what miles your bike has on it? If you have been reading about them you now know what goes wrong with the tensioner when chain gets slack, they don't work very well as the springs loose strength but you can use the small screwdriver down the blanked off hole to see if it is moving at all.
If it was running before it will again before deciding what to do and you will not loose anything except a small amount of your time, it can always be done later just do not get disheartened.

Still just doing my research - not disheartened yet!  The bike currently has 22K miles; three years ago when I rode it, it had 21.7K miles - so not much has changed in that time.  On that ride, I recorded a video to try to capture engine noise - not because I suspected anything wrong, but just because I had no idea what sounds are "normal" for this engine.  I posted this link waaaaaaay back in post #1 of this thread; here it is again FYI:

https://youtu.be/Szxke8bD_dg

I can say that while deep maintenance history is unknown, recent maintenance history appears to have been lacking...

   How much re-tightening torque are we talking about here?
There is no torque, its automatic spring tension that enables the process of adjusting the chain. You only undo the lock nut and adjuster bolt to allow free movement of the chain tensioner adjuster bar to allow the springs to push the chain tensioner adjuster bar to be pushed down further on to the horse shoe, which in turn, pushes the tensioner slipper on to the chain to take up the slack. It's an automatic tensioner. But for the process to work and remove any cam chain rattle from a slack chain, the chain must still be within service limit, the horse shoe pivot not seized and the spring not weak. As Bryan says, worry not now, sort it out at a later date if needed.

We may be talking semantics here.  Since there is a locking nut, I figured that the adjuster wasn't relying on torque alone to hold it in place, but the manual does say to re-tighten it, and to my mind that means some kind of torque - even if the intent is only to tighten it just until resistance is felt.  The answer to "how tight should it be?" is a torque value, isn't it?  The manual reveals nothing on this score...

It maybe worth a look into Julie's engine rebuild thread to fully view the component parts and give yourself a broader picture in overview.

If you want to check if tensioner is moving on a non running engine, loosen the set/pinch bolt,  put something like a small screwdriver against the spring rod, and get someone to turn the crank anticlockwise (looking at ignition side) slowly.
This'll put the camchain into tension on the "wrong" side and should push the rod towards your hand if the pivot etc are free.

If it moves,  then turn the crank clockwise and it should go back away from you again. At this point you can lock the pinch bolt again as all the camchain slack will be placed next to the tensioner and should be adjusted and held by the tensioner.

I'll look again - I read her thread "cover to cover," but it was almost at a single sitting; like binge-watching your favorite TV series, retention sometimes suffers.  Is your "screwdriver against the spring rod" the same as Bryanj's "screwdriver down the blanked off hole"?

Online Bryanj

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Re: New (to me!) '77 CB400F - US model
« Reply #235 on: March 08, 2019, 05:18:34 PM »
Yup it is, 22k if look after and adjusted regularly should be OK, ignored, abused and not adjusted often wrecked------who knows!

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #236 on: March 08, 2019, 05:31:10 PM »
Yup it is, 22k if look after and adjusted regularly should be OK, ignored, abused and not adjusted often wrecked------who knows!

We'll all know... hopefully sooner rather than later!  But right now I've got six-foot snow drifts in my driveway and it was 5℉ (-15C) this morning when I left my house for work...

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Re: New (to me!) '77 CB400F - US model
« Reply #237 on: March 08, 2019, 06:07:51 PM »
Only answer to that is stay in and put more logs on the fire!!

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #238 on: March 08, 2019, 08:59:48 PM »
Only answer to that is stay in and put more logs on the fire!!

True!  Alas, I can't work at my job from home...

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #239 on: March 10, 2019, 04:00:35 PM »
How much re-tightening torque are we talking about here?
There is no torque, its automatic spring tension that enables the process of adjusting the chain. You only undo the lock nut and adjuster bolt to allow free movement of the chain tensioner adjuster bar to allow the springs to push the chain tensioner adjuster bar to be pushed down further on to the horse shoe, which in turn, pushes the tensioner slipper on to the chain to take up the slack. It's an automatic tensioner. But for the process to work and remove any cam chain rattle from a slack chain, the chain must still be within service limit, the horse shoe pivot not seized and the spring not weak. As Bryan says, worry not now, sort it out at a later date if needed.

We may be talking semantics here.  Since there is a locking nut, I figured that the adjuster wasn't relying on torque alone to hold it in place, but the manual does say to re-tighten it, and to my mind that means some kind of torque - even if the intent is only to tighten it just until resistance is felt.  The answer to "how tight should it be?" is a torque value, isn't it?  The manual reveals nothing on this score...

From Haynes - "Turn it again inwards, until slight resistance is felt, then re-tighten the locknut."

 

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