Topic: Cam Chain Tensioner Complete rotation (CB550)

[SAEmiles]

I know this topic has been beat to death, but I wanted to verify before I went down the road of pulling the head, etc.


I have tried tensioning the cam chain on my 77 550F with the engine off and rotated 15* TDC, and I have also tried tensioning with the engine running with similar results.  I have read that the adjuster screw is only capable of a 1/4 turn in either direction and should (under ideal conditions) automatically adjust itself. However I find that mine does not adjust itself, and if I lightly turn the screw I am able to make a complete revolution. When adjusting the screw with the engine running it reaches a point where the chain noise is reduced, but I have not been able to successfully tighten the nut and have it remained tensioned.

In my understanding of the mechanism, this points to a stripped gear, but could this instead indicate that the cam chain is stretched beyond the adjustment range of the tensioner?

[Duanob]

Sounds like you need to pull it out and check it. You will have to pull the carbs, head, exhaust, jugs, etc. I know that's not what you wanted to hear!

[LesterPiglet]

You don't need the cylinders of to check/replace the tensioner iirc.

[SAEmiles]

Yeah, that is what I'm afraid of, but I think it needs to happen. I'm supposed to be riding to the keys memorial day weekend, so I'm trying to get this sorted out.

As far as not taking the jugs off. I read that when you relieve tension from the head studs that it can disrupt the lower jug gasket. Is that just a worst case scenario?

[LesterPiglet]

I removed the head on mine in the view to inspecting the rings/pistons. The cylinders would not budge so I reassembled it. 

[lucky]

When you did not get the results you wanted you then said you tried it with the engine running.

You ran the risk of the cam chain getting very loose and jumping a tooth or more and possibly destroying the engine!!!

I do not know that model extensively but what I would do is do the adjustment exactly as the book says!!!!

You said when you did do it as it was supposed to be done, it did get quieter.
Sounds like it did what it was supposed to.
Do you think the engine is supposed to be absolutely quiet?
What if the cam chain is worn then of course the adjuster can only take out so much slack.

[lucky]

Yeah, that is what I'm afraid of, but I think it needs to happen. I'm supposed to be riding to the keys memorial day weekend, so I'm trying to get this sorted out.

As far as not taking the jugs off. I read that when you relieve tension from the head studs that it can disrupt the lower jug gasket. Is that just a worst case scenario?

The head studs have nothing to do with the cam chain tensioner.

[LesterPiglet]

The head studs have nothing to do with the cam chain tensioner.

Did you miss a reply or two. He's talking about removing the head to check if the tensioner is functioning.

My bike's PO must have tried adjusting the tension by turning that self adjuster as when I checked it the little teeth were all chewed up.

[SAEmiles]

When you did not get the results you wanted you then said you tried it with the engine running.

You ran the risk of the cam chain getting very loose and jumping a tooth or more and possibly destroying the engine!!!

I do not know that model extensively but what I would do is do the adjustment exactly as the book says!!!!

You said when you did do it as it was supposed to be done, it did get quieter.
Sounds like it did what it was supposed to.
Do you think the engine is supposed to be absolutely quiet?
What if the cam chain is worn then of course the adjuster can only take out so much slack.

The head studs have nothing to do with the cam chain tensioner.

I tried tensioning with the engine running because it appeared to be a documented procedure from multiple threads on this forum. When i followed the instructions in the manual it did not get quieter.

Obviously it is not going to be absolutely quiet. I have heard several 550s and my cam chain noise is currently much more prominent.

Maybe I should have been more clear, but my comment about the worn cam chain was a question about the mechanical function of the tensioner. I was asking whether in a situation where the tensioner has no opposing force on it (I.e. an overly worn chain) if the adjustment screw would make a complete rotation, or if it would still only make the ±1/4 turn rotation as in proper operation.

Lastly, the comment about the head studs was a reply to Lester saying that the cylinders did not have to come off when replacing the tensioner.

[Duke McDukiedook]

Which manual are you referring to when you make the adjustment?

I ask this because the Clymer tells me to adjust at 15 degrees like you said but the Honda manual says at TDC for my 750.
Mine was noisy at 15 degrees so I went with the Honda recommended adjustment at TDC and quiet from then on.

[LesterPiglet]

My Haynes manual states this. 15 degrees is the spring post after the 1/4 marks.

[SAEmiles]

Which manual are you referring to when you make the adjustment?

I ask this because the Clymer tells me to adjust at 15 degrees like you said but the Honda manual says at TDC for my 750.
Mine was noisy at 15 degrees so I went with the Honda recommended adjustment at TDC and quiet from then on.

You are right, the manuals seem conflicted on this. However, they both state that that the adjuster should spring to the correct tension automatically, which mine does not.

I think the best option is going to be to pull the head and verify the condition of all the components. I'm looking at gasket kits currently.

[LesterPiglet]

You only need a head gasket. At least that's all I've ever bought.

[Duanob]

I removed the head on mine in the view to inspecting the rings/pistons. The cylinders would not budge so I reassembled it. 

Count yourself lucky. Usually removing the head will loosen the jugs and cause leaks between the jugs and the case.

[Duke McDukiedook]

Try it at TDC before tearing apart the engine if the Honda manual says that, the Clymer manual is wrong about a few things.
 

[SAEmiles]

Try it at TDC before tearing apart the engine if the Honda manual says that, the Clymer manual is wrong about a few things.
 

I will, I'm going to check everything before I resort to a teardown. 

[Duanob]

If you can turn the tensioner screw more than a half a turn I think the tensioner is toast. Good luck with it.

BTW counter-clockwise tightens the chain, clockwise loosens it. 

[Frostyboy]

If you can turn the tensioner screw more than a half a turn I think the tensioner is toast. Good luck with it.

+1
I think I bought the last NOS tensioner in stock here in Aus. I got it from a country dealer in Victoria. I bought it just in case I need it one day. I just opened the wrapping to confirm things for you.

1. The stud is only capable of 45° rotation through the full deflection of the adjuster blade. Any more than that then the 'rack & pinion' is stripped.

2. If the 'rack & pinion" is stripped, there's a slim chance the tensioner could remain locked in the correct position if you perform the adjustment correctly. 15° ATDC on #1 is the instruction in the factory manual.

3. If the  'rack & pinion" is stripped, when you go to dismantle it you may have trouble retracting the tensioner to unhook the chain from the cam sprocket. You might have to try turning the engine backwards with the locknut loose & nip it back up & hope it stays locked in the slack position.

There's a pretty good video on this topic here
http://forums.sohc4.net/index.php?topic=55569.msg598355#msg598355

Looking at the whole assembly, I reckon a good machinist could rebuild it if it came to the crunch.
Good luck with it once again. 

[Dimitri13]

I removed the head on mine in the view to inspecting the rings/pistons. The cylinders would not budge so I reassembled it. 

Count yourself lucky. Usually removing the head will loosen the jugs and cause leaks between the jugs and the case.

Ain't that the truth. I thought I had fixed all my leaks when I replaced the head gasket. Nope, the base gasket started leaking after that -.-

[dave500]

id remove the tensioner and have a look,you risk major damage i think,that screw turning a full turn is wrong,dont risk the ride you planned on,youll get the chain off easy if you unbolt the cam sprocket and let the sprocket wobble off,thatll slacken the chain enough,they can be a fiddle if the sprocket has the plastic guide,i remove them once the sprocket is off.

[Frostyboy]

I set an email alert from David Silver a while ago for when new tensioners are available. I got a message yesterday. It maybe what you want? Be quick, they only have 2 available.

http://forums.sohc4.net/index.php?topic=107057.0

[SAEmiles]

I pulled the head and tensioner last night. The stamped steel part of the tension gear assembly appears to be stripped. I am looking into options for a replacement. Thank you Frostyboy for a heads up.

I do have a question on reassembly though. I have read multiple places that the cylinder needs to be lifted to replace the tensioner. I assume that when the cylinders are lifted that the base gasket absolutely needs to be replaced, but is it possible to reuse the cylinder rings after the cylinder has been removed?

[LesterPiglet]

I replaced mine without removing or lifting the cylinders.

[SAEmiles]

That is good to hear. I'm in the process of cleaning everything this afternoon, and hopefully it will go back together in the next few days

[Duanob]

I replaced mine without removing or lifting the cylinders.

Again, count yourself lucky. I've tried twice with no luck. It worked fine and I didn't want to force it I just wanted to clean it. I think with proper tension and a good spring it will not be easy to get the sucker out. I just sprayed some good triflow into the mechanism as far as I could get it and worked it good so it works good and smooth and left it in place.

Also I have a weep between my case and jugs from the last time I replced the head gasket. I can live with it.