Topic: CB550K Cam Chain Rattle Maybe? SOLVED!! FINALLY!!

[Dr. Frankenstein]

I finished up the starter clutch repair yesterday on the 1974 CB550K and went out to try to start it, and I am happy to report that it started right up! I was very pleased...BUT! I think I hear some cam chain rattle - I tried adjusting it as per the manual, but it's still there. I adjusted the bottom one, but doesn't the top bolt get adjusted too, or is that just me (I don't think so...)

https://www.youtube.com/shorts/NYzoBqFZeuk

Yes, I know I have a leaky #4 carb bowl, I have to fix that next, I think the float is just hung up. I literally just got the bike started. Luckily that's the only one and it's on the outside rather than, say, #2 or 3...

OR...! (And I had this thought while watching the video) - I still have to synch the carbs, too; might that be a factor as well?

[HondaMan]

Certainly, unbalanced carbs (or more so, uneven ignition timing) will cause the chains to "jangle". Then it's hard to tell which one is making the noise?

[Dr. Frankenstein]

I took the carbs off to check the float height of #4, it's at 22mm which is spec - I used the clear tube method to check it again after I polished the needle seat which was a bit dirty, but nothing spectacular. The fluid level looked spot-on at a couple mm's below the carb bowl seam, but it still dripped a bit out of the overflow so I think I'm going to set the float a bit higher and see what happens. I'll also check the tube, too, and make sure that's not cracked. The rest of the carbs 1 thru 3 were fine.

I'll double-check the bench synch too - I noticed the slides appeared a bit lower that what I thought I set them at. What's the correct height for the slides again...? 1/8" of an inch or something like that (using a drill bit)?

On the plus side though she started right up after I completed the starter clutch overhaul!  

[Don R]

 You might also have grit in the float needle-seat, I like to drop the float and remove the needle then turn the fuel back on and flush it out into a clean container so I can see what comes out, if anything.

[Dr. Frankenstein]

I flushed it out with brake cleaner and polished the inside with a Q-tip, but that's a good idea too - do the needle seats in 550's come out? I don't remember...

[HondaMan]

I flushed it out with brake cleaner and polished the inside with a Q-tip, but that's a good idea too - do the needle seats in 550's come out? I don't remember...

Yep!

And in my garage, they are hard to find when they do...

I have turned (over the years) to setting the 'bench sync' to be zero, following the #2 carb after I reassemble them. It's easier to do because I have a nice bench light, and look thru the closed #2 slide to see the shape of the light leak (it's tiny), always looking at the same light source. Then I make #1 the same as #2, then the other 2, which are a mirror-imaged light pattern where the slides are opposite (some types are, some aren't). If you do it yourself, you'll quickly "see" what I mean: I have only had to vacuum-adjust 2 bikes that I even remember, following this routine, when checking the vacuum after startup.

[Dr. Frankenstein]

So by 'Zero' you mean setting the slides at the bottom, right? Totally bottomed out? IIRC I was using a piece of really thin aluminum wire to set a little gap at the bottom...

[M 750K6]

Where they are doesn't matter, so long as they're all in the same place. You can adjust the idle with the screw. I then synch'd them with guages, they weren't much out. I still had chain rattle below 1250-1300rpm tickover, so I set the tickover there.

[HondaMan]

So by 'Zero' you mean setting the slides at the bottom, right? Totally bottomed out? IIRC I was using a piece of really thin aluminum wire to set a little gap at the bottom...

Yep, fully bottomed. The reason I started doing it was that I had to always (always) vacuum-balance a carb set that I had "synch'd up" by using a dowel or drill bit: once by chance I didn't do that, and they came out much closer. Since then I got more practiced at it, and now only do it from 'zero'. I get much better results.

[Dr. Frankenstein]

Here's another video of that noise coming from the engine; can somebody with a better ear than me tell me what this is?  The bike runs fine except for that annoying 'playing card in some bicycle spoke' noise...I tried adjusting the cam chain by loosening the nut, and the cam chain screw is able to be moved to the left and right and should have self-adjusted, yes...?

https://www.youtube.com/shorts/Oo4NLTQT3Jo

And what do you think of my Carbtune levels?

*** A little bit if an update that does not bode well - after reading a bit about the same symptoms here in the forum, http://forums.sohc4.net/index.php?topic=8589.0  I tried running the bike and loosening up the cam adjuster to turn the screw to find out where it's quietest, and I could FEEL and SEE the adjuster screw to MOVING back and forth! I must have done something wrong...But WHAT!? What would cause it to do that? Maybe mis-threaded?? I KNOW the cam chain is mounted on the cam and the lower sprocket, else it wouldn't turn, right?? Mis-adjusted valves, maybe...?

I'll try setting the cam chain slack with the points and check my valve clearances again, but to quote Han Solo "I've got a bad feeling about this." smh/fml! 

[denward17]

Do you have pinned rocker shafts in the valve cover?
In other words, is the valve cover from a '77/'78 550?

[Dr. Frankenstein]

If you mean rocker arm shafts, yes, there are four of them, but I have no reason to believe the valve cover is from another year - the neck ID says it's a 1973 CB550K, so...1974.  What's the difference?

[Little_Phil]

Cam chain tensioner adjustment: The lower nut should be loosened and then the nut retightened to lock the automatic tension adjustment in place. This is done with the motor stopped. The slot in the screw is to hold the screw still as you lock the nut. It is acceptable to use slight ccw pressure at the slot as you tighten the nut. Never try to turn the screw back and forth when the nut is loose as you may well break the crude internal gearing. The upper bolt on the tensioner is just to secure to the head,

[Dr. Frankenstein]

No...I think I found the problem. And it sucks. "Mr. Fast and Loose" here missed putting the cam chain tensioner into its little slot in the lower case...fml/smh...

I dropped the oil pan today and looked up her skirt to see this - I found this post in the Forum and mine looks exactly like it.  http://forums.sohc4.net/index.php?topic=147178.0

Just to confirm, missing putting that cam chain tensioner into its little slot would cause all sorts of rattly noise, yes..?  The pic here is mine.

"Always time to do it twice (or three or FOUR times!) than to do it right."

I'm getting pretty damn good at taking this engine apart.

 

[HondaMan]

Ah! Yep, that's going to be noisy...
While it can be put back in with just the top engine cover removed (and in the frame, unlike the mighty 750), you'll have to pull the cam to do it. The whole tensioner bar must move toward the front of the engine (with the bolts that hold it removed) to get it loose again, then lifted up, then seated...it will be tricky to get the tensioner's fancy middle bolt into it's hole, too. I have had to raise the cylinders slightly (about 1/2" or so) to get that middle bolt back into the cylinder's block (when the engine is already assembled) to get to the (15-degree or so) angle needed to start that fancy "twister" bolt into the cylinder block again: I don't think there's enough room to do it without that move?

But, it is doable without pulling the cylinders entirely.

(You'll note I didn't say it was 'easy'...).

[Dr. Frankenstein]

Yeah, I hear you; It's more of just a PITA than anything else. That was my plan, to take the top end off again and try to just gently raise the cylinder block just enough to get it back in, hopefully without damaging the gasket. And I'm going to do it with the oil pan off so I can be sure I get it into the right place this time!

Pulling and resetting the cam isn't that much of a challenge, actually. I've done it enough times now that I'm getting really good at it! Luckily there aren't any feelable chunks of metal in the oil, but there's a pretty little swirlable silver 'sheen' to it while it's in the drain pan. I'll check for any more serious damage when I get it out.

The work is in progress - I have the tensioner out, but trying to get it into its little hole down there - are those two clips or 'ears' on the side of the tensioner supposed to slide down over the socket/hole or whatever it is that it fits into? I have the tensioner positioned, but it feels like it's really loose, or just sitting on the space where it's supposed to be...or like you say, lift up the cylinder block slightly, fit the tensioner bolt into the hole and then drop the cylinder head down, thereby locking the tensioner into its hole...I'll give that a shot, I just don't want to bend anything that doesn't bend.

UPDATE: I think I got it - I did lift up the cylinder head just a bit to get the tensioner bolt back through the hole, and I think it's where it needs to be - but before I button her up again, does this pic look right to you...?

[HondaMan]

Yep! Looks OK. The 2 little "wings" on the sides of the lower end of those things are supposed to take out any 'slack' in the fitup, side-to-side. But, like is shown in my book, they sometimes end up outside the little pocket at the bottom and rattle sideways anyway: that engine had one in, one out, letting the tensioner rattle at higher RPM like something was "gonna blow soon, Captain!". It was real noisy in the engine in the book, and the owner was really happy to hear how much quieter the engine was when it went home again.

[Dr. Frankenstein]

Hey, HM! Thanks for getting back to me, and the affirmation. I'm putting it back together again tomorrow, watch this space, I will report back.

[Dr. Frankenstein]

Okay, so here's the update: I got the bike back together, the carbs are synched, it runs great at 1200 RPM, but I still have this weird 'buzz' that I do not think is the cam chain (which I did adjust), but it seems to come from the rear of the engine - I'm thinkin' kick starter gear...

https://www.youtube.com/shorts/Z6POYp74l68

I have not yet put this bike on the road to see if the noise goes away when I shift into gear, but what do you think...?  If you listen closely it seems to emanate from the rear of the engine, and I don't think it's the primary chain, but of course I could be wrong; Probably am....but be advised I did not take out the kick starter gear when I rebuilt the engine, I could see that it's driven by another gear in there that I did take out when I was going through it, but did I screw up again by Not taking it out and reassembling it? Other than that, it sounds pretty good, I think...

("Other than THAT Mrs. Kennedy, how was Dallas...?"  )

[scottly]

That sounds like the cam chain is rubbing against something it shouldn't be rubbing against?

[Deltarider]

Are you sure it is inside? First step always is to eliminate something not fastened well that can be solved easily.
For further diagnosis, hold screwdriver against engine and put your ear to the grip. 

[Dr. Frankenstein]

Scottly, yes, it does, but when I fixed the cam chain adjuster I made sure I could move the little slotted screw and nut around, so I don't think it's that - the noise seems to be coming from the rear of the engine somewhere, and the only thing in there I can think of that would make that ratchety sound is the kick starter assembly, which was working fine when I rebuilt the engine - I didn't touch it.

Delta, I do have a proper mechanic's stethoscope that I used to try to locate the noise, but to no avail. I will however go over the engine and frame again just to make sure, but I'm pretty sure I have everything locked down. 

I have read varying things about the 'normal' rattles for these bikes - what is 'normal'?? And what about the clutch basket...could the clutch somehow be responsible for that noise?

[denward17]

Scottly, yes, it does, but when I fixed the cam chain adjuster I made sure I could move the little slotted screw and nut around, so I don't think it's that - the noise seems to be coming from the rear of the engine somewhere, and the only thing in there I can think of that would make that ratchety sound is the kick starter assembly, which was working fine when I rebuilt the engine - I didn't touch it.

Delta, I do have a proper mechanic's stethoscope that I used to try to locate the noise, but to no avail. I will however go over the engine and frame again just to make sure, but I'm pretty sure I have everything locked down. 

I have read varying things about the 'normal' rattles for these bikes - what is 'normal'?? And what about the clutch basket...could the clutch somehow be responsible for that noise?

How far to the left and right are you turning the slotted screw?

[Dr. Frankenstein]

It'll rotate about 70 or 80 degrees to the right, and about 20 degrees to the left...I just had the tensioner out when I put it back properly in its hole, and seemed to be able to turn the gear in the tensioner just fine...

[rosewood]

Yeah, I hear you; It's more of just a PITA than anything else. That was my plan, to take the top end off again and try to just gently raise the cylinder block just enough to get it back in, hopefully without damaging the gasket. And I'm going to do it with the oil pan off so I can be sure I get it into the right place this time!

Pulling and resetting the cam isn't that much of a challenge, actually. I've done it enough times now that I'm getting really good at it! Luckily there aren't any feelable chunks of metal in the oil, but there's a pretty little swirlable silver 'sheen' to it while it's in the drain pan. I'll check for any more serious damage when I get it out.

The work is in progress - I have the tensioner out, but trying to get it into its little hole down there - are those two clips or 'ears' on the side of the tensioner supposed to slide down over the socket/hole or whatever it is that it fits into? I have the tensioner positioned, but it feels like it's really loose, or just sitting on the space where it's supposed to be...or like you say, lift up the cylinder block slightly, fit the tensioner bolt into the hole and then drop the cylinder head down, thereby locking the tensioner into its hole...I'll give that a shot, I just don't want to bend anything that doesn't bend.

UPDATE: I think I got it - I did lift up the cylinder head just a bit to get the tensioner bolt back through the hole, and I think it's where it needs to be - but before I button her up again, does this pic look right to you...?

I don't think its related to your buzzing sound but I noticed in this pic that your primary chain is starting to wear the lower case where an oil gallery is. Not sure how long you want to run it like this. maybe others will have more experience in this area...? Or have you replaced the primary chain already in which case disregard my comment..