Topic: CB550K cam chain tensioner stripped

[chadheins]

I recently bought a CB550K and I went to adjust the cam chain, so I start loosening the lock nut. I'm sitting there turning and turning, and I realize it's going nowhere. The nut is seized to the screw and the hole is stripped out. What do I do?
Thanks,
-Chad

[Jonesy]

There is a slot in the end of the cam chain adjuster screw. The screw is meant to fit loosely in the hole in the cylinder, as there is a gear on the other end of it that moves two rack gears that are connected to both ends of the tensioner. When the gear pulls the racks together, the tensioner blade bulges outward, tensioning the chain. When the ends move apart, the blade flattens, loosening the chain. The locknut is there to hold it in place after adjustment. Sounds like you might have a burr on the end of the threads, or the slotted portion may have spread slightly, causing the nut to bind.

Here's what your tensioner looks like on the inside, minus the tensioner blade:


And the gear I was talking about:

[fastbroshi]

   Sounds like it's stripped.  The bike either won't run or you'll damage something soon running it like this.  To get it out for an asessment, you'll have to pull the rocker cover and raise the barrels a bit, so count on getting a topend gasket kit, and least a new tensioner assembly.  Depending on wear, the leaf spring that applies tension to the chain may have to be replaced as well.  This isn't in Jonesy's pic, but if you've seen the rear suspension on a pickup, you know what they look like.  Except this one is just one metal strip covered in a rubber/plastic compound that wears with time, even with perfect adjustment to the mechanism.
  The reason yours is just turning non-stop is the gears that mesh in the middle have distorted and are slipping.  You may be able to get the nut off if you hold the slotted screw part while turning the nut, or you may have to cut off the nut like I did before it will come out.  I did mine with a carbon blade on a dremel, painstaking but it worked.

[Jonesy]

Here's the blade:

[bryanj]

If the screwdriver slot can be turned and turned the tensioner is knackered and thats a cylinder off job. If its just the nut try carefully cutting it off and hope the threads on the stud are OK

[Hush]

Or you could try using a hacksaw to cut a slot in the end of the threaded part and holding it with a bladed screw driver.
Might have to cut (or grind with a dremil) the end of the nut off too as I think they are those strange rounded end ones.
I'd do anything not to have to remove the heads or barrels.

[chadheins]

Okay well basically, I need to ride it for a while, I can't tear it down yet. I was thinking if I can get it pried out a little bit, will the cam chain tension up? I was going to stick some razor blades inbetween the nut and the case. Or is it really a lost cause trying to do something like that?
Thanks for all your help and Jonesy if you could take another picture of the other side so I can see what the screw actually does that would be great
-Chad

[fastbroshi]

I recently bought a CB550K and I went to adjust the cam chain, so I start loosening the lock nut. I'm sitting there turning and turning, and I realize it's going nowhere. The nut is seized to the screw and the hole is stripped out. What do I do?
Thanks,
-Chad

  From your quote above, even if you were able to get the nut off, it sounds as if the slotted screw part's gears arent meshing correctly, meaning depending on the load on the motor, the tension on the cam chain is constantly changing.  This cannot be good. 
  If you were on four wheels your idea of just letting it go for now might suffice, but let's say that chain lets go at 65mph?  What then?  Not to try and scare you or anything, but I'd take it as more serious than a water pump leak on your Camry.  Is this really your only transportation?