Topic: Confusion about the CB500/550 cam chain tensioning

[Deltarider]

The purpose of this thread is to gather all info availabe and also to inventory your experiences*.
Let me confess that I am still in the process of trying to understand why Honda confused us with several methods for adjustment, but never sought to modify the tensioner.
Let's start with the Owner's Manuals. At the time when you bought a new CB500 or CB550, there was such a manual under the seat. It had a maintenance scheme and also explained what you could do yourself.
In the first Owner's Manual that I had (p.48), the procedure was:
   a. Set the crankshaft to T.D.C of the compression stroke with the kick pedal
   b. Adjustment is made by loosening the tensioner lock nut. This will automatically release the tensioner bolt,         applying the proper tension to the cam chain.
   c. After completing the adjustment, tighten the lock nut.
      Source: http://www.honda4fun.com/pdf_libretti/500/CB500_k1/CB500_K1_3.pdf
Simple? Well, no... a. it doesn't specify what T.D.C is ment and c. leaves us wondering what there is to 'complete', if the process is supposed to be 'automatical'. Furthermore the method is not consistent with the procedure in the Shop Manual CB500-550 (p.13) where the crankshaft is in the position 15^o ATDC.
In the Owner's Manual next in time, the one that happens to cover my model, the CB500K2-ED (marketed in 1976), there's NO information on adjusting the camchain. Why is that? All the other maintenance info like ignition timing and adjusting the valve tappet clearance is still present. Strange.
Source: http://www.honda4fun.com/pdf_libretti/500/CB500_75/libretto500_1.pdf
Finally the Owner's Manual that deals with the K3, both the CB500 as well as the 550.
On p.68 we read:
   1. Start the engine and maintain it at idle speed (1,050 rpm).
   2. Loosen the tensioner lock nut and tensioner bolt. When they are loosened, the cam chain tensioner will             automatically position itself to provide the correct cam chain tension.
   3. Retighten the tensioner bolt and lock nut.
      Source: http://www.honda4fun.com/pdf_libretti/500/CB500_550/CB500_550_06.pdf
Confusion again. Under 2. one could conclude that the bolt also needs loosening, the more when we read under 3. Retighten the tensioner bolt and lock nut. We know this is not right. We are not supposed to touch that bolt. Why did Honda decide to go dynamically, remains a mystery.
So, overseeing the differences on the matter in three consecutive owner manuals, we wonder:
What made Honda decide to omit the instructions in manual #2?
Why did Honda inform us owners again but now advised to do it with a running engine in manual #3?
This against the background that Honda mechanics in The Netherlands and the UK had learned a different approach that we here now know as 'Bryanj's method'.
Please realise that the camchain and its tensioner system is a hundred % identical for all CB500/550 models: from the very first CB500 up to the last model CB550K4.
* Like: What method worked for you? Are there any of you that had success with the dynamic method? What is your opinion on the prescribed interval of 3000 miles?

[Maraakate]

I don't think TDC is too vague.  I would assume it means on Cylinder 1.  This is what I have done for my 77 CB550K and appears to be just fine.  I just loosen the lock nut, then retigthen.

The BryanJ method you mention sounds more of a flat-rate way of getting it done.  It sounds like it takes a good feel to know how to do it.

The other way mentioned in the service manual with 15deg ATDC is essentially the same as the previous way mentioned in the owners manual; except we got a bit past the T mark at TDC.  It's probably more accurate this way, but my guess is the owner's manual fails to mention it because it probably doesn't make that much of a difference.

However, this is all speculation on my end.  I think any way you choose to do it is fine, as long as the chain isn't slapping around in there.

[Maraakate]

For completeness sake, the BryanJ method is at http://forums.sohc4.net/index.php/topic,11818.msg112760.html#msg112760

And here it is quoted, in case the thread gets lost.

OK forget all the boks and try the "mechanics" method i been using on all Hondas for WAY to many years!!

Using either the kickstart OR the BIG nut on the spark advancer put tension on the crank so that it is just about to turn, this tightens the front run of the camchain and puts all the slack in the "adjustable" side. Lossen and re-tighten the locknut whilst holding the pressure on the crank.

On the 500/550 you need to loosen the nut till it turns freely; on the 750 loosen the locknut and then the bolt till it turns freely.

YEH I KNOW you need 6 hands or a mechanicaly trained spider BUT with practice it can be done--If I can anyone can.

When you get used to it you can do a full service on any four with one revolution of the crank--and believe me when you are on a bonus payment saving any time at all is important!

[bryanj]

My way, when you are doing it on the lift inside Honda "book" times means that you only have to look through the hole at the marks when setting points and timing.
Under sevice conditions the tank and all tappet covers come off first with ramp on floor then lift ramp drop oil and filter, adjust chain and rear brake lube chain look at disc pads.
Turn engine over till you can see a cylinder with valves on the rock check other cylinder( no feelers you have been doing it that long you can tell 2 and 3 thou by feel) rotate crank 180 do 2 more tappets repeat twice more adjust cam chain manualy refit drain plug and new filter fill oil using bulbopen points gap till bulb lights on T mark for each pair check gap at points refit tappet caps lower bike connect vac gauges and dummy tank start up and check sync as bike warms adjust when warm if necessary(rare in a bike you see regularly) disconnect gauges fit plugs in manifolds rifit tank test ride and adjust clutch if necessary.
Spark plugs and air filter fit in when required which is not every 3000.

To do the 3000 service you were allowed 2 1/2 hours if memory serves and that included getting parts from parts man

[Maraakate]

My way, when you are doing it on the lift inside Honda "book" times means that you only have to look through the hole at the marks when setting points and timing.
Under sevice conditions the tank and all tappet covers come off first with ramp on floor then lift ramp drop oil and filter, adjust chain and rear brake lube chain look at disc pads.
Turn engine over till you can see a cylinder with valves on the rock check other cylinder( no feelers you have been doing it that long you can tell 2 and 3 thou by feel) rotate crank 180 do 2 more tappets repeat twice more adjust cam chain manualy refit drain plug and new filter fill oil using bulbopen points gap till bulb lights on T mark for each pair check gap at points refit tappet caps lower bike connect vac gauges and dummy tank start up and check sync as bike warms adjust when warm if necessary(rare in a bike you see regularly) disconnect gauges fit plugs in manifolds rifit tank test ride and adjust clutch if necessary.
Spark plugs and air filter fit in when required which is not every 3000.

To do the 3000 service you were allowed 2 1/2 hours if memory serves and that included getting parts from parts man

Makes sense.  I did auto body work for about a decade and know all too well how silly the book times can be.  I also did this work at a dealership and worked with some automotive mechanics and they dreaded doing warranty work because most of those times were so slim you could almost never make money on some of those jobs.  I was a lot happier when I found a dealership that had "hourly with incentive".  I eventually gave it all up to go into software development.

[Deltarider]

Still we wonder why it's done with a running engine in the CB500/550K3 manual. In other words: what made Honda changed its mind? At first I thought it was an error: copy and paste from some other model, but the pic on that page is definitely a CB500/550.
Anyone has experience with that method?
Also from experience I can tell you that the prescribed interval for adjustment (5000km) is a joke. All the 40 years that I have owned my bike, I had to do it every 1600 km at least. And it was not just me.
Adjusting the valve tappet clearance on the other hand was usually not needed.

[Maraakate]

Still we wonder why it's done with a running engine in the CB500/550K3 manual. At first I thought it was an error: copy and paste from some other model, but the pic on that page is definitely a CB500/550.
Anyone has experience with that method?
Also from experience I can tell you that the prescribed interval for adjustment (5000km) is a joke. All the 40 years that I have owned my bike, I had to do it every 1000 km at least.

I suppose you could do it with the engine running.  I know that's how the CM400's do it and they're made around the same time-era.  Not sure how similar the designs are though.

Really?  I never noticed the noise get louder on my CM400 and it was non existent on the CB550.  I've just stuck to doing it like once or twice per season.

[bryanj]

Honda were consistently reviewing their service methods and times and probably changed it to be more consistent with other models, i didnt care i had a method that worked and stuck to it

[Deltarider]

Probably I've made a mistake yesterday. Having read about an extra washer, I loosened the lock nut to take it of, add a washer and replace the lock nut by a new (flange) nut in the process. Alas, the nut wouldn't come of. I suspect the slot of the tensioner just a tiny bit widened, prevented the lock nut to come of. Before I realised this, I must have turned the nut a couple of times extra and I am afraid the bolt must have turned with it. Didn't want to start the engine, not before I have consulted you guys on what my options are.

[bryanj]

Do you mean you used a locking nut on the bolt? It should only be a plain nut.
You may be lucky and be able to hold the bolt with a screwdriver to undo the nut.
If, in fact, the bolt has spread there is not much you can do except replace the tensioner assembly which you can get a repro for but it aint cheap plus you have to take the head off.
I wrote about a second washer but that was, i think, because the wrong steel washer was fitted and the bolt was still loose when nut was tight on thread

[flatlander]

to not make matters easier: i've been doing the 15' ATDC method. also that has been working fine.

so my guess is that it's not all that important how you do it, but that you do it. you need to get the tensioner the opportunity to adjust itself (by unlocking the nut), the rest it seems to do just by itself.

[Maraakate]

Probably I've made a mistake yesterday. Having read about an extra washer, I loosened the lock nut to take it of, add a washer and replace the lock nut by a new (flange) nut in the process. Alas, the nut wouldn't come of. I suspect the slot of the tensioner just a tiny bit widened, prevented the lock nut to come of. Before I realised this, I must have turned the nut a couple of times extra and I am afraid the bolt must have turned with it. Didn't want to start the engine, not before I have consulted you guys on what my options are.

Oh no!  Why did ya goof with it?

[Maraakate]

Honda were consistently reviewing their service methods and times and probably changed it to be more consistent with other models, i didnt care i had a method that worked and stuck to it

This tends to be the way of shop life.  Sometimes the way the book says it is not always the fastest way, or even the best way.  Usually it is, but over the years people in the shops learn of tricks that work well.

This comes back full circle to what I said earlier that as long as the method you use is getting the proper tension and you can accomplish the task in a reasonable timeframe then it's good enough and you shouldn't need to worry about it so much.

[Deltarider]

Oh no!  Why did ya goof with it?

Because I have to do the adjustment like every 300km or so and therefore wanted to check if there was something wrong like maybe a slipping lock nut. Camchain is probably worn. It has done 56.000kms and from our British brothers I have learned that that's about what you can expect. 
This is where I am. Engine starts rightaway and pulls wonderful as it should.
It seems my only option is:
a) Loosen the lock nut.
b) Prudently keep the tensioner bolt with a screwdriver counter clockwise (carefully avoiding to exercise force inwards ofcourse) whilst fastening the lock nut. I can also do this dynamically with a somewhat raised idle. If I release the screwdriver before fastening the lock nut, chain becomes too noisy, so I conclude tensioner bolt still does something. How much? I have no clue.
Checked once more in the partslists if there have been any modifications. Nope. At CMSNL however I see the chain is superseded by 14401-362-003.
Looks like I have to live with a raised idle.

[Maraakate]

I'm confused on the frequency of every 300km.  How did you come to this determination?

[Deltarider]

I'm confused on the frequency of every 300km.  How did you come to this determination?

When after a ride I enter town again and engine wants to stall at a traffic light unless I raise the idle, I know enough.

[Maraakate]

I'm confused on the frequency of every 300km.  How did you come to this determination?

When after a ride I enter town again and engine wants to stall at a traffic light unless I raise the idle, I know enough.

Are you positive that your air adjustments on the bottom of the carb are dialed in?  And after verifying this you have verified carb sync?  This may be a dumb, but sometimes it's easier to overlook things.  It's possible that the o-rings behind the spring and washer are now garbage and it's not doing it's job anymore.  As the engine wears you may also need to readjust the air adjustments and doing a carb sync.

I had a problem initially with getting proper idle on my CB550K until I completed those procedures.

Can a worn chain really cause a bad idle?  I figured if it was at that point where it was so worn or the tension was way off that you would hear it, possibly slapping around in there.   Do you hear noises?

[Deltarider]

Hope to post a sound recording as soon as I have managed to understand my smartphone. Ign timing is fine, sync is fine. Unlike yours the older style carbs air screws do not have an O-ring.

[Maraakate]

Hope to post a sound recording as soon as I have managed to understand my smartphone. Ign timing is fine, sync is fine. Unlike yours the older style carbs air screws do not have an O-ring.

Oh wow, so yours is a true air screw whereas mine is a fuel adjustment screw.