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Discussion Starter · #1 · (Edited)
I could not find anything on the cx650 cam chain tensioner in the quick reference list,
So I thought I’d create this thread for future reference.
Below is a picture of the engine with rear case off. The chain is at the end of its life. The tensioner is all the way out and there is not any slack in the chain. Probably the most perfect time to replace a chain before it gets wobbly and ruins something.
Of course, this is also a good time for me to replace the mechanical water pump seal, the oil seal behind the mech seal, theoil seal which is around the shifter exit, and check the starter clutch assembly for nicked or worn rollers and springs. But this thread is just for resetting the tensioner.
 

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Discussion Starter · #2 · (Edited)
The tensioner is all the way out. I will not replace the plastic chain guides. They are in excellent shape. I have owned three CX650’s and this is my third cam chain replacement.
Anyway, I have never found unusable guides or an unusable tensioner. If they are wrecked, it is probably because the chain went beyond its useful life and chewed them up.
The tensioner is held on by a single bolt and positioned by a dowel pin. It is easy to remove. Just remove the bolt and wiggle the tensioner off the guide pin.
 

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Discussion Starter · #3 · (Edited)
The tensioner has two dowel pins. They do not need to be removed unless you plan on disassembling the tensioner for repair or curiosity. One goes through into a slot in the plunger and keeps it from popping out of the housing completely, the rear pin keeps the steel ball from falling out the backside.
 

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Discussion Starter · #4 · (Edited)
The basic design of the tensioner goes back thousands of years. It is a design that can be configured various ways and is mainly used in traps. It is a sliding angle with a wedge that drops along the angle by gravity. The wedge (in this case a steel ball) allows the slide to move forward, but not to retract.
I have a squirrel trap that uses the same principle. It’s also good for trap doors in tombs to seal in grave robbers. They can get in, but they can’t get out. Unless someone on the outside removes the wedge, which, of course, is what we need to do to the tensioner.
 

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Discussion Starter · #5 · (Edited)
To reset the tensioner - you need to push the ball back in while depressing the plunger. Use something like a pencil or wood dowel to push on the ball. You do not want to dent or scratch the ball or slide faces.
With the ball pushed in, and plunger retracted, put a nail or something similar to hold it in the retracted position. That's it. When you have the new chain in and guides and tensioner all put back together - remove the nail.
 

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Good write up.
 

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Discussion Starter · #7 · (Edited)
FYI, there does exist a web page that describes an extension mod for the tensioner.

I do not want to reference it because I'm not convinced the author is correct about the short-commings of the auto tensioner, or that the mods are a must-do for it to work correctly.

Something interesting about the mods he suggests is that the author wants you to add hole T1 according to his sketch. Well, hole T1 is already in the casting of my tensioner, and it is not an owner mod, its casted as you can see in the picture above.
So this leads me to wonder if Honda fixed the problem themselves during production.

Anyway, if a person has a tensioner that is sticky and does not move freely, ya, I would disassemble it and give it a looksy. More likely a burr on the casting or slide from machining or an imperfection in the ball.

However, if you give the tensioner more reach, yes, you will get more miles, but now the chain is also being stretched beyond its operating limits and it will be more prone to a break, which will result in a horrid mess.

Penny wise and dollar foolish in my humble opinion. Just change out the chain anywhere after 30k and no more than 40k. My chain above has 35k on it. It is well stretched already. I would not want a modified tensioner to stretch it even more. Yikes!
 

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Ronj10,

Excellent article! Thanks

I see your measurement of the adjuster appears to be about .85 inch or 21.6 mm which is about the same as the adjuster in my CX500TC with 27,000 mile. Got a question for you: what will the measurement be with a new chain?

Still running Against The Wind
 

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Very timely thread, I'm putting a GL650 engine back together right now. I was completely unable to find a new chain so I picked up one on ebay that supposedly has 14000 mi on it. It would have taken me some time to figure out how to reset that tensioner. BTW, mine was even worse than yours...
 

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Very timely thread, I'm putting a GL650 engine back together right now. I was completely unable to find a new chain so I picked up one on ebay that supposedly has 14000 mi on it. It would have taken me some time to figure out how to reset that tensioner. BTW, mine was even worse than yours...
Was the direction of the ebay chain marked? Makes a difference. David Silver Spares U.S. has them, same as the cx500
 

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Very timely thread, I'm putting a GL650 engine back together right now. I was completely unable to find a new chain so I picked up one on ebay that supposedly has 14000 mi on it. It would have taken me some time to figure out how to reset that tensioner. BTW, mine was even worse than yours...

fm..........sorry,if I were you I WOULD NOT use a used chain ............but that's me
 

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Was the direction of the ebay chain marked? Makes a difference. David Silver Spares U.S. has them, same as the cx500
The seller said the chain was marked for reinstallation. I did't know what that meant.... until now :)
 

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Now I remember. DS is out of stock David Silver Spares USA - Honda CX500 DELUXE 1980 USA Cam chain. I clicked on "request an email alert" and never heard anything. I agree it would be a shame. I have a NOS starter clutch in it, a restored camshaft from Web, NOS lower rocker arms, and all new seals etc etc. Sorry, didn't mean to hijack the thread...
 

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Discussion Starter · #14 ·
Ronj10,

Excellent article! Thanks

I see your measurement of the adjuster appears to be about .85 inch or 21.6 mm which is about the same as the adjuster in my CX500TC with 27,000 mile. Got a question for you: what will the measurement be with a new chain?

Still running Against The Wind
Sorry. Im waiting for gaskets and an oil seal to come in the mail. I have not replaced the chain yet because I am going to do all the rear case work at once. I rebuilding my front forks in the meantime.
 

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Discussion Starter · #15 ·
Was the direction of the ebay chain marked? Makes a difference. David Silver Spares U.S. has them, same as the cx500
Now that is really interesting. Could you expound on that chain direction? Is this specific to the 500's?
This is my third chain replacement and the first I have heard of chain direction. My official OEM CX650 Honda shop manual does not mention it, and I have an OEM chain and it has no marks indicating direction.
 

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I will jump in here and try not to sound like a know it all.
My interpretation would be that if you are using a new chain it does not matter which direction you put it on. Those of us that possess of certain amount of rear end qualities will always install used parts to run in the same direction as they have been running so the parts do not have to wear in again to the small differences of the matching parts. This would apply to all parts like bearings, pistons, valves, bushings and fork tubes. This may be something you wish you never heard about because now you will fret over it like others of us.

I like your penguins
 

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FYI, the 82 GL500i also has the auto-tensioner.
I found out early on when trying to find the tensioner adjust bolt.
:rolleyes:
John.
 

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Discussion Starter · #19 · (Edited)
I will jump in here and try not to sound like a know it all.
My interpretation would be that if you are using a new chain it does not matter which direction you put it on. Those of us that possess of certain amount of rear end qualities will always install used parts to run in the same direction as they have been running so the parts do not have to wear in again to the small differences of the matching parts. This would apply to all parts like bearings, pistons, valves, bushings and fork tubes. This may be something you wish you never heard about because now you will fret over it like others of us.

I like your penguins
I found that out the hard way. The bought a set of used rear blinkers. Had to take em off and switch em around to get em to blink in the right direction. Now I only buy new parts.;)
 

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Discussion Starter · #20 · (Edited)
Ronj10,

Excellent article! Thanks

I see your measurement of the adjuster appears to be about .85 inch or 21.6 mm which is about the same as the adjuster in my CX500TC with 27,000 mile. Got a question for you: what will the measurement be with a new chain?

Still running Against The Wind
Looks like .550 to .600
 

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