Topic: Cam chain adjustment

[Duanob]

1976 CB550

Does anybody have any instuctions a bit less "Greek" than these:
"Warlock's view on best method for 500/550
The camchain tensioners on the 500/550's are designed to be self tensioning. What this means is that the slotted screw is actually the visible part of an internal half moon gear which mates with a spring loaded rack gear inside the tensioner assembly. Ideally, when the lock nut is loosened, the spring will pull the tensioner, pushing the slipper against the chain, and rotating the adjusting screw automatically, as needed, in the process. The adjusting screw is then held stationary while the lock nut is tightened. All this is done with the engine set at #1 cylinder at 15 degress ATDC on compression(the position at which the chain slack is designed to be on the tensioner side). Over time, the rack and half moon gears may become gummed up and not operate freely. Thus, the spring may not be able to move the tensioner attached to the rack gear. It has been suggested that a small amount of torque be applied to the adjusting screw while tightening the lock nut. This is to overcome any resistance which has manifested itself in the adjusting mechanism. Loosening the lock nut and exercising the adjusting screw has also been an option. Be careful not to apply too much force to the adjuster screw, as the slotted ends  have been known to break under excessive force...and THAT would be a problem..."

I followed them as I was working on the bike but in the end I couldn't tell if I tightened the cam chain or not. Does anybody have the HONDA manual instructions? This sentence did't make a bit of sense to me when I was working on the bike:
"rotating the adjusting screw automatically, as needed, in the process"

Do you rotate the adjustment screw in or out to tighten? Thanks.

D

[MCRider]

My understanding is you just loosen the locknut, let the adjuster spring do the work, which includes turning the screw, then hold the screw at its positoin and retighten the lock nut. "You" do not turn the screw at all.

Except as he noted, if the mechanism is hanging up, you could "exercize" the screw turning it in and out to free things up. But ultimately, you would release the screw and let it find its own position driven by the spring.

The biggest conflict I have is that the instruction for 15deg ATDC is for the CB750 which is done stationary. I thot the 500 was done with the engine running?

[Duanob]

Wow you explained it beautifully! That's exactly what happened. I backed the lock nut off and when I tightened it the screw started turning. I was trying to keep it from turning but now I know what to do. Thanks!

As far as adjusting it's while running it will have to wait until I get it running. Anyone else know for sure about this?

[TwoTired]

Honda instructions say to adjust cam chain on the cb500/550 with the engine NOT running.

They are also adjusting a brand new engine with no wear grooves in the tensioner screws.

If the chain still seems "noisy" after a stationary adjustment on a well worn engine, you can run the engine at a purring, low idle and apply *just* enough torque on the screw slot to where the chain quiets.  Then lock down the nut.  This latter procedure is done at your own risk by those who feel their prowess is a level above the competence of Honda engineers and tech writers.

Cheers,

[bryanj]

If you look in the FAQ's, as suggested before posting, you will find an explanation of how it works plus:-

http://forums.sohc4.net/index.php?topic=369.msg315851#msg315851

[Deltarider]

If you look in the FAQ's, as suggested before posting, you will find an explanation of how it works plus:-
http://forums.sohc4.net/index.php?topic=369.msg315851#msg315851

Follow the manual as far as positioning the engine with #1 cylinder 15 degrees before Top Dead Centre (TDC).

should be read as
Follow the manual as far as positioning the engine with #1 cylinder 15 degrees after Top Dead Centre (TDC), though.

[Tintop]

If you look in the FAQ's, as suggested before posting, you will find an explanation of how it works plus:-
http://forums.sohc4.net/index.php?topic=369.msg315851#msg315851

I think he did, considering his 'Warlock' quote is verbatim from the thread you quoted.

[Duanob]

"should be read as
Follow the manual as far as positioning the engine with #1 cylinder 15 degrees after Top Dead Centre (TDC), though."

Glad someone's payin attention. I caught that and did just that. bryanj still doesn't explain what to do with the screw adjustment. You're telling me on an old engine, the screw just happens to place itself in the proper location? Not buying that. It needs to be either turned in or turned out to tighten the cam chain. When the lock nut is loose the whole thing moves in and out. The screw doesn't turn much except when the locknut is being tightened. If that's the procedure tehn I'll leave it at that.

TT "Smooth running idle" You funny man! It will be a while for that. I think it will be tight enough to satisfy the 3000 maintenance schedule and hopefully move on to the carbs. Thanks for all the help, this board is priceless.

[domer]

its "supposed" to set the tension when you back off the nut, then you hold the screw (?) in that position while tightening the nut. mine didnt work like that anymore, and after trying many times over... i broke down and did it while running. at idle, loosened the locknut, very very very gently turn screw/bolt thingy (i think thats the tech term )i had to turn counter clockwise, might not be the same for you... just till the noise disappeared. it only moves a little bit, and do not force it!!!!!  worked fine for me, wish i had done it the first time.

[Duanob]

Thanks domer, what year and bike do you have?

[domer]

72 CB500.

[TwoTired]

You're telling me on an old engine, the screw just happens to place itself in the proper location? Not buying that. It needs to be either turned in or turned out to tighten the cam chain.

You have not seen how it operates, have you?  The internal spring moves the shoe towards the chain when the lock nut is loosened.  If it doesn't, it's broken.  I don't believe the entire rotation equates to more than 1/4 turn of the post/stud.

When the lock nut is loose the whole thing moves in and out.

Normal.  It behaves as a pinch bolt in that regard.  The stud/post is multifunctional.  Rotation does one thing, stud tension another.

The screw doesn't turn much except when the locknut is being tightened.

Locking down the post pinches the adjuster/slider into position, whatever arch the spring created on the shoe arch piece.
If the post moves while you are tightening it, then the threads are fcuked up and it needs repair.

It's only a 10mm nut.  Doesn't need 50 ft pounds of torque to tighten.  And, the gorilla approach will damage/strip the threads. (I found one like that.  I have to use a double nut on that one.)

As far as age is concerned.  It is a mechanism.  Works as well old, just as the pistons do.  The only "age" factor would be if the spring lost its tension from fatigue.

I'm guessing you are making this far more difficult than it actually is.  Stop projecting how you think it works onto how it actually does.

Position the crank, loosen/remove the lock nut and examine the threads in both parts.  If they are good and sliding properly, tighten the lock nut down, and move on to the next task.

Cheers,

[Duanob]

Thanks TT you're probably right about making it more difficult but this thread has cleared up how to actually do it. If it's as simple as positioning the crank 15 degrees after TDC, loosening the bolt and retightening it, that's what I've done so far. As said before I may wait until I get it running and retry it to see if it quiets down. Unfortunately due to electrical problems (new post) I can't get it running. No juice to the starter or anything else. Ah fixers!

[bryanj]

When I wrote it there was no mention of 15 degrees as it dont matter a stuff where the engine is AS LONG AS ALL THE SLACK IS IN THE REAR RUN which is what you do by putting tension on the big nut on the auto advance and pushing clockwise.

TT is also right in all he sez about the mechanism, if you try and force the screw you will have nothing but agro afterwards

[Deltarider]

Nowadays I have to adjust my camchaintensioner every 300 km! That tensioner is by far the worst designed part in the engine. It is as if Honda didn't expect their motorcycles to do more than 40.000 km. On the other hand, I remember in those days more manufacturers had problems producing a sound camchaintensioning.

[Duanob]

Got it! I finally got the thing started up long enough to adjust the cam chain by sound. Loosened the lock nut, turned the screw counterclockwise and it quieted right up. Tightened the locknut while holding pressure counterclockwise on the screw. Voila! Now on to the carbs....

[Old75_ratafe]

I know this is slightly off topic but I'm wondering if this is the noise I am hearing on my old 750... I know their supposed to be a little loud and rattly but this sounds excessive.  Especially on cold start up but it will rev like a champ to 8k no issues.  at idle (which I currently have set at around 1200) I hear it a little almost a "loose" sound... kinda hard to describe.  And before anyone asks my oil pressure is good (according to my mechanical gauge).   I know the PO did 0 maintainence and the bike has just under 32,000 on it.  I've also noticed after my carb rebuild even on a cool day it requires NO choke.

[Lars]

I have just been through all the adjustment procedures on my first CB 750 K4, and here is my experience. (Also based on experience with my CB 350 F and CB 550 K)

To have a real smooth running engine, all adjustments has to be done properly and in the correct order. Points gap, timing, spark plugs, valve adjustment, cam chain tensioner adjustment and finally the carb synch. On my CB 750 I did all this, but still I had some real rattling which I identified comming from the clutch housing. So, I adjusted my clutch according to the owners manual, and only THEN the engine ran perfectly. However, the CB 750 do rattle a little in the clutch housing idling in neutral. Press the clutch lever inn, and most of this rattling is gone. The better carb synch, the less rattle. The carb synch makes the engine run more evenly, which also positively "calm down" the primary chain, which again have influence on the clutch basket.

In my opinion, if you are not satisfied with how it runs, you just as well start from the beginning and do it all.

[jimbir]

Great video here. Helped me a ton.

[CoachDoc]

That video is exellent. I never really understood how the 550 tensioner physically adjusts the tension until I saw it. Now the whole adjustment process makes sense. Thanks for posting.

[Danno]

listen to two tired he knows what he is talking about and If i remember right turning it slightly to the left tightens and a little to the right loosens there is not much turning here as it drives a half moon gear and the device does the rest I only rotate it a little left and right if it is stuck once it is unstuck i loosen it at idle and it will turn automatically when it stop turning I hold it with a screw driver and tighten the nut gently

[CoachDoc]

You're telling me on an old engine, the screw just happens to place itself in the proper location? Not buying that. It needs to be either turned in or turned out to tighten the cam chain.

You have not seen how it operates, have you?  The internal spring moves the shoe towards the chain when the lock nut is loosened.  If it doesn't, it's broken.  I don't believe the entire rotation equates to more than 1/4 turn of the post/stud.

TT is right- seeing how it operates makes understanding the adjustment process simple. Just did mine and this time I feel good about it. Before I never knew if anything was happening. Design of the adjuster perhaps not the most outstanding example of 70's Japanese motorcycle tech