Topic: Stuck on cam chain adjustment

[mikethejeepguy]

Guys... please don't kill me for posting on this topic, but I have searched and searched, downloaded and read manuals, but am still stuck... literally. The PO seems to have reefed on the retaining nut on the cam-chain adjuster (1976 CB550F) and I can't for the life of me loosen it.

I've put the motor 15deg past #1 TDC. I try to hold the screw part with a screwdriver (even a ratchet with a screwdriver bit) and loosen the retainer nut with a 10mm wrench, but it is virtually impossible to hold the screwdriver in place. The screw turns with the nut, the whole thing eventually torques out and the screwdriver slips out. I'm afraid of breaking off the sides of the screw that make up the slit in the middle or mess something out on the inside. I've sprayed it with penetrating oil but still no go. Is it bad for the screw part to turn with the retaining nut? This is my first time adjusting the cam-chain so I don't know if I can "F" something up or not. Any tricks? Any tools I should try to get? At this point I'll dance around the bike in a coconut bra if that's what it takes!

I can't believe how a small screw and nut like this can be THIS FRUSTRATING!!

Help?

M

[mystic_1]

The 550's tensioner is all internal, unlike our 750s.  Replacing it is an engine-out proposition.

Sounds like maybe the nut is stuck to the stud with corrosion?  How long did you let the penetrating oil sit on there?  I'd hit it several times over the next 24-48 hours with the penetrating oil and then try again.  Applying heat might help, don't set the penetrating oil on fire!

You can also take a spare screwdriver and grind it down narrower (but not thinner) so that it fits inside the nut, that way the nut won't push your screwdriver out of the way when it turns.

The manual says you just have to loosen the locknut and then retighten it.  Never worked on a 550 so dunno what the spinning stud means but it doesn't sound right to me.

mystic_1

[mystic_1]

Here's what the tensioner assembly looks like:


click for larger image

See also:
http://www.cmsnl.com/honda-cb550k3-four-usa_model1015/partslist/E++05.html

Looks like the threaded stud is part of the tensioner blade assembly. #11 is the adjuster locknut I think.  One of the 550 experts will be along shortly with more useful information

Someone posted a video of this part recently, was that Martino?

Off to search...


mystic_1



Edit: Found it.... Martino made the adjuster video, but it's for a 650.  Think the tensioner arrangement is the same though.

[OldSchool_IsCool]

As you can see by Martino's vid, the post with the stuck lock nut is attached to a pinion gear that engages a rack that actuates the metal backed rubber "bow" (aka slipper).  By setting you engine to 15 degrees past TDC, the cam chain is at it's loosest.  By releasing the lock nut, you are allowing the spring loaded slipper to take up any slack.  Locking it down again prevents the chain from pushing the slipper back.

That being said, Mystic's advice is prolly the best thing to do now.  Soak it a few times with penetrating oil (PB Blaster is popular here) until you can get the lock nut and post to turn independently.  Once it's loose, do what you have already described to set the tension and lock it back down.

To replace the tensioner assembly can be done with the engine in the frame, but the engine has to be taken apart significantly!  Changing the tensioner usually means changing the cam chain too.  To do that by the book, ur looking at an engine out, case split rebuild.  Got my fingers crossed that the penetrating oil works for ya.

[mikethejeepguy]

Guys, thanks so much for your replies... That video helps quite a bit. Luckily I didn't let the bolt turn more than a few degrees, so I hope I didn't bugger anything up (fingers crossed).

I'll hit it with s'more with the penetrating oil and maybe give it a few love taps. Maybe the vibrations will help for the oil to work it's magic. There doesn't seem to be much corrosion on the outside of the adjuster, but who knows whats in between the threads and the nut. Worse comes to worse I'll try the heat approach. If that doesn't work... well maybe it's time to call in a professional to look at her. Doesn't Honda have a special tool for this?

Once again, thanks for the advice and apologies for beating some more on this dead horse topic Now it's off to bed and off to squirt some more lube on my nut in the morning! Man I hope it works.

M

[mikethejeepguy]

Just had an idea... what if I was to put two nuts on the end of the tensioner bolt and tighten them to each other so they lock.... but leave enough space for tensioner nut to loosen? That way I would eliminate having to use the screwdriver to hold it in place, and hold in place with a wrench instead. I wonder if that would work....  Wonder if I can find two nuts skinny enough to fit on there?

[toycollector10]

Try some PB Blaster. It's great stuff.


http://www.pbblaster.com/test.html

[wrenchmuch]

If penetrating oil doesn't work you might try a nut splitter or dremel to cut the nut off and just find a new nut .

[mystic_1]

Good thinking.

mystic_1

[schneider419]

and after you get the hard part done, put a dab of high temp. anti seize on the threads where the nut lives. it will make the job much easier the next time. you can get that at any auto parts shop. good luck.

[mystic_1]

Just had an idea... what if I was to put two nuts on the end of the tensioner bolt and tighten them to each other so they lock.... but leave enough space for tensioner nut to loosen? That way I would eliminate having to use the screwdriver to hold it in place, and hold in place with a wrench instead. I wonder if that would work....  Wonder if I can find two nuts skinny enough to fit on there?

You could also try finding a small acorn nut to fit on the end of the stud, it'll thread down only so far and then stop, you can then use a wrench on that to hold the stud in place while you turn the locknut.

Use care!  Breaking the nut is no problem, breaking the stud looks like a BIG problem.

mystic_1

[mikethejeepguy]

Fantastic ideas! DREMEL! Why didn't I think of that... antisieze... totally! Acorn nut... worth a shot for sure. You guys rock! MAN I love this forum! It's like a warm fuzzy blanket when you get in mechanical doo doo!

I'll post my progress, trials, and tribulations with this for future generations of CB newbs.

Thanks again guys!

Mike

[toycollector10]

Hey Mike, what's the story behind that crazy avatar you've got there. Does he have a pet cow? Is the cow restrained? What stops the cow from jumping out of the sidecar. These, and many, many more questions!

[fastbroshi]

   I went through this on my 550 myself, though I ended up torquing the locked on stud enough that it stripped the gear inside, necessitating a removal of the tensioner assembly.  So I ended up cutting off the locked on nut and stud with a dremel.  If I had thought about it before stripping the gear inside I probably would've tried to cut the nut first before I started assembling everything.  Clearance is going to be your biggest issue I think.
  If you do end up having to take out the whole assembly, to clarify what Mystic said, it's not an engine removal but the top end will have to come off.  This consisted of the rocker cover, cylinder head, and barrels because they have to be lifted from the block a couple inches for the tensioner to clear.  So I replaced the base gasket.  Maybe you can get away with not doing it, but I didn't want to have to do it twice.   It can be done with the engine in the frame.  Good time to replace the cam chain too.  I was pleased with the Vesrah top end gasket kit for this job. 

[WFO]

My PO did the same thing all i did was tap a 12 point socket on it and it came right off then i replaced it.