Topic: '75 550K Cam Cover Wear?

[Popwood]

I've concluded that the clickity noise on my K5 550 K is not from my inability to precisely set my valves but from the cam cover wear from the rocker shafts. The bike has just over 11K miles. Inspecting the studs in the cam cover end caps I noticed very, very, very tiny shiny bits and assume it's aluminum. I closely inspected the tappet access cover caps and there's no visible signs of tappets striking the insides of the covers.

Searching the forums here I see this is an issue with this model year and improvements were made in the late 1976 models where the the rods were pinned preventing rotation. I also read an early fix prior to that improvement (Mike Nixon) was inserting O-rings behind the shaft plugs to compress the rods and prevent them from rotating. The ultimate solution being replacement of the cam cover with one from 1977 or later.

Question. I've inserted the O-rings and the clickity/clackity has quieted some but not totally. Does it stand to reason that if the O-ring solution works, after inserting them it's necessary to go through the valves and set the clearances? Anyone have experience with this? Like Two-Tired?

I'm in the line-up (possibly) for longer ride in the advancement of our Lizard Godzilla in the coming days but am concerned about putting more miles on the bike if the rocker rods are likely to damage (or further damage) the the rocker arms or cam.

Advise, please– and thanks.

Popwood, aka Steve

[reddyvv]

Here is a post I made with my theory, as putting o-rings on the outside did not solve the problem in my particular case.

http://forums.sohc4.net/index.php?topic=122627

The wear on my engine suggested that the o-rings needed to be between the shafts to push the shaft out as the inside of the bearing surface was worn out. Pushing the shaft out fixed the problem. Only issue is you'll need to take the cover off to insert the O-rings between the shafts.

[lone*X]

The wear to the rocker shaft bores, if present, is visible when you remove the end caps.  See below.  If the shaft is not centered, but offset to the top, then your bores are worn.  The wear is gradual.  As long as the wear isn't excessive and you are getting good oiling to the rockers and shafts I would not be afraid to ride it that way.  If its excessive the only fix is to replace the rocker cover.  As for the O rings, they have to be thick to really press on the shafts and keep them from rotating, but that is all they will do.  The O rings will not realign the shaft in the bore, too much spring preasure pushing up on the rocker for it to make a difference.  The O rings are not a fix for the worn bores or a noisy valve train.  You can still get a good valve adjustment even with slightly worn bores, you may just have to do it a bit more often.   Adjust your valves to spec and double check your work and make sure the lock nuts are secure.   These bikes made valve noise when they were new.  It's part a parcel with mechanical valve adjusters.  In fact some noise is better than no noise, which would indicate a too tight adjustment and the chance of burning valves. 

If you need to change the valve cover, some late 76 and the 77/78 models had the improvement.  See below for identification.  I borrowed the first image years ago and don't recall the source, but it is a good visual as to identifying the worn bore.  the second image is the late model cover you would want to find as a replacement if needed.


   

[TwoTired]

Question. I've inserted the O-rings and the clickity/clackity has quieted some but not totally. Does it stand to reason that if the O-ring solution works, after inserting them it's necessary to go through the valves and set the clearances? Anyone have experience with this? Like Two-Tired?

I've done both repairs oring and cover replacement.  I much prefer the newer cover style.  The first pic that lone*X posted is from me.  When the gap gets that bad, stuffing orings in there won't cure the problem.  Worse, the ill geometry wears the rocker to cam interfaces rapidly.  So, it's best to not run it until the cam is inspected, at least.  If already worn on one edge of the cam lobe face, it and the affected rockers will need replacement anyway so running it that way a bit longer won't really matter much or hurt anything else further for a few thousand miles.
As to readjustment after oring insertion, it takes little time to check the clearance and adjust if necessary.  It IS a routine operation.  But, the orings aren't a cure for the shaft to bore gap or noise.  Just a hopeful wear limiter.

I'm in the line-up (possibly) for longer ride in the advancement of our Lizard Godzilla in the coming days but am concerned about putting more miles on the bike if the rocker rods are likely to damage (or further damage) the the rocker arms or cam.

If you have that gap as pictured,  the rockers and cam are usually worn outside of spec already.  The basic idea of the orings is to jam the rockers in the bores so they won't turn.  But, if the bores are already too sloppy, it doesn't really do much.  In a way, less oil between shaft and cover is a good thing.  The more friction you get there means it is more likely the rocker will move in the steel shaft than have the shaft move with the rocker to wear the soft aluminum bore.

An old trick to locate the noisy tappet is to put your thumb on the adjuster while running.  It can be messy with the oil flying about.  But, the noise pretty much goes away when you've found the noisy one.  Remember, set the tappets cold.  The gap should close up when the engine is warm and the valve stem expands.  And, the clearance reduces even more when the engine is hot.  They should not make zero noise like hydraulic tappets.

[reddyvv]

The issue of more or less lubrication to the rocker shafts is an academic exercise today, as we are stuck with what we have. No one is going to make parts of improved design.

However from an academic and technical point of view my experience with many motorcycles (which admittedly is marginal in respect to the SOHC's) suggests the root cause was due to a lock of oiling and the factory fix was a Band-Aid rather than a solution. It is a design no-no to have an oscillating bearing surface contacting a non-rotating bearing surface. One only has to look at the design of more recent '80s and later engines - or look at any piston/wrist pin design. I totally agree with Hondaman's opinion....

http://forums.sohc4.net/index.php?topic=7401.msg94128#msg94128

[RAFster122s]

reddyvv,
Sorry, that link is to CB750 shafts being pinned and the design changes on the 750 rockers. Totally different design than the cb550 which has the rocker shafts and rocker arms in the cover. The ends of the shaft can wear egg shaped or eccentric. The aluminum wears from the shafts rotating rather than the rocker arms moving on the shafts.
TwoTired weighing in the on issue and he is an expert on the subject. His photos were used by another poster in the thread if you read the earlier posting. 

Honda intended the rocker arms to move on the shafts and did not anticipate the shafts moving causing wear in the covers where the shafts were held in place. Their bandaid on the 550 was to change the '77 and '78 to use a pinned shaft design to force the rocker arms to move on the shafts. It is not a question of lube for the rocker arms and shafts, just a bad design decision by Honda on the 550 causing a weakness that is revealed with time.

[reddyvv]

reddyvv,
Sorry, that link is to CB750 shafts being pinned and the design changes on the 750 rockers. Totally different design than the cb550 which has the rocker shafts and rocker arms in the cover.

The same thing happens on the 750 as the 550, no difference. The cover wears if the shaft is unpinned and the shaft wears if the shaft is pinned.

[Popwood]

Thanks for your input, all. Very informative and helpful.

As mentioned, I inserted the O-rings at the shaft ends between them and the studs on the cover caps. There was some, but little improvement. I then checked valve clearances and No. 1 intake was way out of adjustment and the others weren't too far out. I adjusted them all, then went ahead and reset the points, cam chain tensioner and finally the timing. I was all smiles when I fired it up. There was NO clickity/clackity tappets. Went for a test ride and for a few miles everything was great– more power, running very smooth and quite. Then I opened her up for a quarter mile or so on a steep hill. That's when I heard the tappet noise return. Not as bad as before, but distinctly audible. Seemed to be in cylinder No. 1.

Back home, I let the engine get back to cold. Went back through tappet adjustment and made some very slight adjustments, mostly tightening ever so slightly. Fired it up and no tappet noise. Headed down the street and less than a mile later the tappet noise was back. Again, not nearly as bad as before the tune-up and lash adjustments, but certainly there. Power was still good.

Any further thoughts on this?

Thanks.

[TwoTired]

Sounds like just putting in orings is not enough.  You need to inspect and report about actual wear of the shaft holes to see if there is some.  The oring addition is NOT a cure all, but a stop gap.  If wear has occurred, you need to replace the cover or live with the tappet noise.

In my spare time, ( ) I thought up a scheme to reuse worn covers.  The valve spring pressure always wears the bearing surface toward the top of the cover, but never the bottom.  I speculate that if a hole were drilled from the outside and tapped, a screw (set screw, sixteen of them)  could be used and inserted to push the shaft back to the bottom of the hole and keep it from turning and making further wear. 

I do have couple of worn covers to experiment upon.  But, it adds another project to the queue.  Just what I need. 

However, if wear is found on yours, and you aren't happy to do some machine work, get a late model cover.

[RAFster122s]

I'm not a machinist but I did have a machine tools class in college a few decades back where I learned to operate a lathe, mill, etc. That being said and a little knowledge being dangerous...
How difficult would it be to align bore the rocker shaft openings in the head and sleeve them? I would imagine the cost at a machine shop would be $$ given the time to setup to do this 4 different places on a 500/550 cover.
Would probably need to fabricate some pads to bolt up to the top of the cover to make it easier to clamp squarely for the machining operation as well. With CAD today and some 3d scanning it could be done without too much difficulty matching the contours.  But, as long as the later covers are available, then it probably isn't worth the time and $$ to test the theory.

David

[Popwood]

Thanks, everyone,

So here's another update followed by an uneducated thought about a fix for the original cam cover wear.

The update: There's definitely an "eggcentric" shape on No. 1 intake side rocker shaft bore. Curiously, upon start up cold today, the tappet noise was not present. I didn't run it long enough to get fully warmed up, but I'm assuming the clickity/clackity would return when hot. So looks like I'll be searching for that later model cam cover. I've checked a couple places (like Western Hills Honda here in Cincinnati) and as expected, no stock, but I did learn a NOS would run about $350.

Now, about that non-machinist fix idea . . . . If the objective is to keep the rocker shaft pressed down in the bottom of the bore that's not worn, why not simply drill and tap holes in the cam cover above the shaft bores? Install a set screws and call it a day. If need be, grind a bit of a flat on the rocker shaft ends. Seems this would only be necessary for Nos. 1 and 4, intake and exhaust.

[TwoTired]

Now, about that non-machinist fix idea . . . . If the objective is to keep the rocker shaft pressed down in the bottom of the bore that's not worn, why not simply drill and tap holes in the cam cover above the shaft bores? Install a set screws and call it a day. If need be, grind a bit of a flat on the rocker shaft ends. Seems this would only be necessary for Nos. 1 and 4, intake and exhaust.

Wow, you're idea is just like mine!  Imagine that!   

The screws/set screws would need to be placed over each position that had bores worn egg shape.  There is some concern about the screws staying tight, both for unscrewing and for oil leakage.  I expect locktite could be employed to help with that, (or jam nuts).

The other concern is if the bores are also worn fore and aft as well as upward, the shaft may wander fore and aft if the screws don't stay really tight.  When I was last thinking about this, two used late model covers came up on ebay for $40 ea., and I won them both.  So, my interest in the set screw as well as boring and sleeving the worn covers waned significantly.

The covers I have are actually worn at each position, it's just that some were worse than others and one was so bad the rocker was hitting the inspection cover.  Certainly, if there are bores that are unworn, a set screw would keep them from becoming worn in the future.

Also, recall that if one support end of the shaft has a bore worn more than the other end, then the tappet follower contact face won't remain flat with respect the the cam lobe flats.  This will wear off the very thin hard coat on the tappet on one edge, then galling follows.  The rocker shaft is supposed to be parallel with the cam lobe flat to evenly transfer spring loads across the entire lobe flat.
Minimize work if you want, but be sure you haven't just postponed a problem developing later on.

[InTheStreet]

I know that Skipp's salvage yard has several 550's with nearly complete engines in them since you're in Cincy.  If you go there, don't trust him on year, check yourself.  I don't think that all pre-77's had issues, as my 75 has over 52000 on it and no sign of wear, so it may be worth getting one I'd the price isn't too bad.  Be prepared to haggle.  If you can make an offer on price before he tells you, you'll be way ahead, and don't let him charge you a "look-around" fee.  That's not something that is standard policy for them, but they got me with it the first time I went.

[RAFster122s]

Popwood, if you happen to go to Skipp's salvage, if they have the little rubber wedge that fits on the front of the top of the airbox I would like one. I am missing this piece for my 550. There are one or two guys on here looking for the spring clip for the back of the airbox that holds the filter in place forward against the airbox seal.
Thanks!