Author Topic: Cam chain tensioner  (Read 3141 times)

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Offline clayherget

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Cam chain tensioner
« on: January 29, 2021, 05:36:34 AM »
Newb here so I hope this hasn't been run into the ground elsewhere.

Working on a 77 cb550k.  Trying to adjust the cam chain tensioner.  I can spin the lock nut but the slotted screw spins with it.  I have spun the lock nut and the slotted screw maybe 360 degrees maybe not quite.  I have also spun it back a little to make sure I am not putting too much pressure on the tensioner.  I spun it that much because when I was first trying to loosen the lock nut I was using a socket when I realized that I wasn't "breaking" the nut I switched to a side wrench and realised the slotted screw was spinning with the lock nut. 

So I have two questions.  The first one is: have I broken the cam chain tensioner by turning that slotted screw so far? 

The second is: Are there any good tricks to get the lock nut to release the slotted screw?  I am soaking it in WD daily and trying to hold the slotted screw while I use a side wrench to try to release the lock nut but I don't want to put much pressure on the slotted screw for fear of breaking it.

Offline newday777

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Re: Cam chain tensioner
« Reply #1 on: January 29, 2021, 06:04:55 AM »
Do yo not have the service manual?

Use 2 wrenches.
1 to hold the bolt from turning.
1 to loosen the nut.

Once the nut is loose, loosen the bolt and adjust. Then tighten nut as you hold the bolt with wrench so the bolt doesn't move as you tighten the nut to lock the adjustment bolt.
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline goodtryer

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Re: Cam chain tensioner
« Reply #2 on: January 29, 2021, 06:21:16 AM »
This may help: http://forums.sohc4.net/index.php?topic=87205.0

Some pictures from a guy who was in the same spot.
"Tolerance will reach such a level that intelligent people will be banned from thinking so as not to offend the imbeciles."
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1977 CB550K
1978 CB750K
1973 CB500K

Offline flatlander

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Re: Cam chain tensioner
« Reply #3 on: January 29, 2021, 06:22:49 AM »
Once the nut is loose, loosen the bolt and adjust.

that's where it goes wrong for most: you don't actually adjust. you just loosen the nut and let it self-adjust.
the slot in the bolt is not for screwing, it's only there to hold it in place while you tighten the nut again. that's why it's not a normal screw had but that weird slot. if you twist and turn that bolt it will break.

Offline bryanj

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Re: Cam chain tensioner
« Reply #4 on: January 29, 2021, 07:15:36 AM »
To answer your question yes you have fubared the tensioner by rotating the screw but from your description it may well be the po's fault and it was fubar before you got to it.

Some times they can be fixed but to do so the tensioner needs to come out which means head off
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

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Offline clayherget

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Re: Cam chain tensioner
« Reply #5 on: January 29, 2021, 07:38:52 AM »
BryanJ thanks for answering my question.  I was afraid of that.  I would still like to try to get that lock nut off though just in case it's not broken by some miracle because this bike is in decent shape.  It starts electrically and with the kickstarter.  It has a top end rattle that made me believe that I needed to adjust the cam chain tensioner and I'd like to try to avoid taking the top end off if at all possible. Is there a better method than what I am doing?  I am just soaking it in WD40 and gently applying pressure to the nut while holding the slotted screw with a screwdriver.  I am being gentle so I don't break the slotted screw.  Also, would the world end if I started it and that tensioner is broken?

Offline flatlander

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Re: Cam chain tensioner
« Reply #6 on: January 29, 2021, 08:15:07 AM »
you can also try a mix of ATF and acetone. it penetrates better than WD40. and/or apply heat to the bolt. its expansion/contraction may loosen it up some more. the problem is that you can't apply much torque without killing the screw.

Offline bryanj

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Re: Cam chain tensioner
« Reply #7 on: January 29, 2021, 11:15:46 AM »
The problem is on the other end of that slot is like a nail head with teeth that meshes with teeth on a rack in the mechanism, forcing it pushes the sides of the mech apart and the teeth never mesh again till repaired so the cam chain dont stay tensiones
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline oldfart

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Re: Cam chain tensioner
« Reply #8 on: January 29, 2021, 03:23:28 PM »
No.  Dead wrong.  The slot is there for your use.  Rotating it adjusts the tension. 
Mike Nixon
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Offline bryanj

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Re: Cam chain tensioner
« Reply #9 on: January 29, 2021, 07:02:21 PM »
Been doing these since they were new NO IT ISNT
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline flatlander

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Re: Cam chain tensioner
« Reply #10 on: January 29, 2021, 11:53:05 PM »
indeed, it isn't. go read the manual and search for all the posts on here telling about buggered up tensioners due to misuse of that slotted bolt.
also look at the link that goodtryer posted. it shows clear pictures of the mechanism.

Offline trigger

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Re: Cam chain tensioner
« Reply #11 on: January 30, 2021, 12:43:12 AM »
No.  Dead wrong.  The slot is there for your use.  Rotating it adjusts the tension.

The Tensioner has a spring that makes it automatic once you release the nut.

Mr Bryan J know what he is taking about and has explained it correctly  ;)

Offline oldfart

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Re: Cam chain tensioner
« Reply #12 on: January 30, 2021, 08:13:27 AM »
Nope.  Very false.
Mike Nixon
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Offline scottly

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Re: Cam chain tensioner
« Reply #13 on: January 30, 2021, 09:16:58 AM »
Try reading the manual, Mike. ;)
Don't fix it if it ain't broke!
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Offline Flyin900

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Re: Cam chain tensioner
« Reply #14 on: January 30, 2021, 11:08:01 AM »
Try reading the manual, Mike. ;)

Scotty,

I have the factory manual HONDA CB500-CB550 July 20th 1977 and that is not listed anywhere in the manual on page 12-13 on cam chain adjustment. That being said Brian J seems correct that the adjuster has a geared drive that does mesh into the cam chain tensioner as shown on page 47 of the manual.

So it appears that there are a number of variations on this adjustment with a question if you should actually adjust it manually or not. It seems to show that the tensioner does automatically adjust after setting the #1 cylinder to ATDC using the timing marks and the spring mounting peg on the points plate in the manual I am referencing.
« Last Edit: January 30, 2021, 11:15:16 AM by Flyin900 »
Common sense.....isn't so common!

1966 CL77 - 305cc - Gentleman's Scrambler
1967 CL175K0 - Scrambler #802 engine
1972 CB350F - Candy Bacchus Olive - Super Sport
1973 CB350F - Flake Matador Red - Super Sport
1975 CB400F - Parakeet Yellow - Super Sport
1976 CB400F - Varnish Blue - Super Sport
1976 GL1000 - Goldwing Standard
1978 CB550K - Super Sport
1981 GL1100 - Goldwing Standard
1982 CM450A - Hondamatic
1982 CB900C - Custom
1983 CX650E - Eurosport
1983 CB1000C - Custom X 2 Bikes now - both restored
1983 CB1100F - Super Sport - Pristine example
1984 GL1200 - Goldwing Standard

Offline flatlander

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Re: Cam chain tensioner
« Reply #15 on: January 30, 2021, 12:09:38 PM »
here's page 12/13 of the CB500/550 manual:



let's please stop spreading this nonsense about having to turn the screw to adjust tension. you'll just make more people destroy this mechanism.

Offline scottly

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Re: Cam chain tensioner
« Reply #16 on: January 30, 2021, 07:33:15 PM »
Try reading the manual, Mike. ;)

Scotty,

I have the factory manual HONDA CB500-CB550 July 20th 1977 and that is not listed anywhere in the manual on page 12-13 on cam chain adjustment. That being said Brian J seems correct that the adjuster has a geared drive that does mesh into the cam chain tensioner as shown on page 47 of the manual.

So it appears that there are a number of variations on this adjustment with a question if you should actually adjust it manually or not. It seems to show that the tensioner does automatically adjust after setting the #1 cylinder to ATDC using the timing marks and the spring mounting peg on the points plate in the manual I am referencing.
The info I posted was from the Owners maintenance manual; perhaps Honda didn't think it was necessary to include the warning about applying force to the screw in the shop manual, which was intended for trained techs? In any case, the tension is Automatically set by loosening the lock nut. 
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Offline Little_Phil

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Re: Cam chain tensioner
« Reply #17 on: January 31, 2021, 08:22:26 AM »
I have 5 tensioners from 1971 to 1977. They are all the same. When loosening the locknut look closely at the slotted end to make sure it does not rotate with the nut. Hold a driver in the slot to keep it still if required. Loosen only maybe half to one turn. Also put a driver in the slot when finally locking the nut. The tensioning is automatic and the internal gearing from slotted screw to tensioning spring is crude and easily damaged. Also when rebuilding the top end after the tensioner is in place push the blade back from within the engine (again do not use the slotted screw) and lock in place to give minimum tension to allow for maximum slack in the cam chain to ease assembly

Offline Flyin900

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Re: Cam chain tensioner
« Reply #18 on: January 31, 2021, 02:37:04 PM »
Also when rebuilding the top end after the tensioner is in place push the blade back from within the engine (again do not use the slotted screw) and lock in place to give minimum tension to allow for maximum slack in the cam chain to ease assembly

Interestingly the above is the normal procedure on most cam chain tensioners I have worked on when rebuilding, yet it isn't what the FSM indicates to do to lock the tensioner in place when reinstalling the head. They indicate using the screw to remove tension and then lock down the tensioner with the nut.

It frankly is a weird set up and one wonders why they deviated from the blank slug style of rod and made this a threaded style of adjuster on that rod?
« Last Edit: January 31, 2021, 02:44:13 PM by Flyin900 »
Common sense.....isn't so common!

1966 CL77 - 305cc - Gentleman's Scrambler
1967 CL175K0 - Scrambler #802 engine
1972 CB350F - Candy Bacchus Olive - Super Sport
1973 CB350F - Flake Matador Red - Super Sport
1975 CB400F - Parakeet Yellow - Super Sport
1976 CB400F - Varnish Blue - Super Sport
1976 GL1000 - Goldwing Standard
1978 CB550K - Super Sport
1981 GL1100 - Goldwing Standard
1982 CM450A - Hondamatic
1982 CB900C - Custom
1983 CX650E - Eurosport
1983 CB1000C - Custom X 2 Bikes now - both restored
1983 CB1100F - Super Sport - Pristine example
1984 GL1200 - Goldwing Standard

Offline bryanj

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Re: Cam chain tensioner
« Reply #19 on: January 31, 2021, 06:29:12 PM »
Because it doesnt move in and out to tension it rotates
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline Ichiban 4

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Re: Cam chain tensioner
« Reply #20 on: January 31, 2021, 06:48:11 PM »
Try reading the manual, Mike. ;)
_____________________________________________________________________
Thanks for that Scott..
I've also adjusted the tensioner on my '77 550K many times..just as instructed.  Works every time.
Think the hang-up is that many think that screw is for adjusting it.  But it's actually just to allow the tensioner spring to self-adjust after the lock nut is loosened..but to keep the screw stable so it doesn't turn.  Have heard that many-a- tensioners on these 500's-550's have been damaged from a misunderstanding of how it works.  Then you have to pull the cam cover to remove the tensioner..and repair or replace.  School-of-hard-knocks I guess..
Cheers..Al/Ichi
Al Summers

Present: '77 550K
Past: '73 CB450(twin), '72 CB175, '68 CB350, '58 Ariel Square 4 (1000cc), '58 Matchless Typhoon (650cc single), Whizzer Motorbikes '48 -'55 (Pacemaker & Sportsman)..Vespa, Lambretta scooters..etc.

Offline oldfart

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Re: Cam chain tensioner
« Reply #21 on: February 01, 2021, 05:02:25 AM »
User forums are, some would say, simply microcosms of powersports ownership community.  That they are essentially egalitarian, democratic, even grass-roots in nature.  This seems an intelligent, comfortably reasonable, powerfully simple defense, but it is actually a very simplistic one and very wrong.

Powersports forums are essentially incestuous. They are destroying the industry through the misinformation that ensures that new powersports consumers are ignorant.  If a large number of people believe a thing, it must be true.  Yet rallying around a falsehood, celebrating it, codifying it, repeating it incessantly, in no way adds value to it.  Opinion unmoored in objective, qualified fact has an echo, but no substance.  Forums are completely silent on literally hundreds of issues vital to powersports consumers, while at the same time their leaders think their discoveries and observations exhaustive, definitive, despite their actually being very limited.  It's like someone reading a book on the subject of war and from then on lashing out at the decorated military veteran whose real experience questions their superficially informed view.  And the more authoritative the questioner, the more vitriolic and confrontational the attack. This should constitute a resounding alarm for any thinking person. 
Mike Nixon
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Offline clayherget

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Re: Cam chain tensioner
« Reply #22 on: February 01, 2021, 09:44:57 AM »
Wow!  This conversation escalated kind of quickly.  I really was just trying to learn some good tricks for loosening the lock nut which is stuck as all get out.  I have soaked it in liquid wrench, WD40, a new kind of liquid wrench, and acetone.  I have been doing this for about a week.  I have also tapped it with a ball ping hammer being careful to not damage the slotted screw.  I briefly tried to heat it with a small blow torch but have not really used that attack in full force but I will.  At the end of it all, I am probably going to have to replace the tensioner anyway unless I get lucky and can fix it.  Either way I am mentally preparing to remove the head and possibly get a new tensioner. 

Where would be the best place to try to get that tensioner?  I have seen them range from about $50 to $300.  Would rather get one for $50.

Offline bryanj

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Re: Cam chain tensioner
« Reply #23 on: February 01, 2021, 09:52:16 AM »
The $50 one is probably a used and knackered in the same way, the $300 will be a NOS Honda part, Dave Silver sells repos that i understand are very good but never had one in my hands.
If you must go used try somebody on here as we all like to think we are reputable, alternatively a breaker you can walk into and inspect the part properly having taken advice on what to look for
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline flatlander

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Re: Cam chain tensioner
« Reply #24 on: February 01, 2021, 10:05:24 AM »
sounds like you're at a point where only brute force will get it off. if you do need a replacement, ask in the parts wanted section. someone on here might have one.
i could give you a few sources that may have used ones but that's here in europe. you're better off trying locally first.