Topic: Cam lobe wear. Excessive.

[crinklesmith]

So I pulled the rocker box off the 550k2 today, to have a look at the cam chain tensioner, and low and behold, the #1 cyl intake lobe has apparently suffered a full out nuclear strike.

Lobe


#1 intake rocker, left side, exhaust on right.


The intake rocker has an odd wear pattern on it, I think this might just be from the galling on the lobe, as all of the other rockers in the engine had the same dull sheen as the #1 exhaust rocker. The bike only has 10k miles, and the valves were adjusted properly at the time of purchase about a month ago. Runs great, nothing points to a sticky valve or any other top end problems. I think its either corrosion or bad oil\extended change intervals, although I didn't see any sludging. None of the other lobes are galled, but they are worn pretty extensively on the ramps, is this a common problem with the low sulphur oils nowadays? The rocker box and head journal saddles had no scratches or gouges, and the cam journals were smooth, and showed no noticeable wear, and the valves still adjust to spec and the tappets line up nicely with the stem. Do you guys think it's ridable while I look for a new cam, or is this a potential timebomb? At least the chain tensioner turned out to be working fine! 

[B.O.X.N.I.F.E.]

Eek, I definetly wouldn't run that as is. Was there any metal flake in the oil? I would imagine it would have done more damage if it had been run like that for any period of time, but if it's recent you should have seen some specs in the oil. Whats the bottom of the pan/screen look like?

[fuzzybutt]

had the motor been sitting a while before you started it? looks almost like really bad rust followed by the motor being turned.

[crinklesmith]

The odd thing was the pan was pretty near spotless when it was pulled 2 weeks ago. Screen was clean too, no sludge. It's coming off again tomorrow, and I'm going to try to plumb up an oil pressure gauge to the fitting under the points cover, haven't had the oil light come on while running, but going to check it just to be sure. Also going to dissect the oil filter, although it only has a couple hundred miles on it.

Because of the miles, and the originality of it, I think it did spend a lot of time sitting at some time in the recent past. The more I think about it, the more I just want to pull the whole top end and give it a full going over, with a nice valve job and maybe some porting. Things might be a little moldy and stale in the valvetrain department after all that downtime.

[mystic_1]

I agree that looks like rust damage, perhaps sometime in the distant past?

I wouldn't run it like that, right now only your cam and rockers are thrashed.  If a metal flake breaks off and lands in just the right (read:wrong) place.....

<dun dun dunnnnn>


mystic_1

[motorhead55]

I am in the process of putting my LOW mileage (9800mi) '76 550F back together and my cam although not near that much had wear also. Mine came apart to reseal the leaky head orings. I am now in the process of using the QUAD rings instead of O rings for the oil pressure gallies. I'll report on how they work.

ONE thing that I think could be suspect is the two alignment dowels at each end of the cylinder base have an oil control orifice in each of them. I have thought of enlarging mine a little to get more oil into the cam lobe lube sump. It looked like one of mine was somewhat plugged. One side feeds one half of the cam. I think that the cams must be soft. I can tell you first hand that a new cam is just about unobtainable.

[TwoTired]

Check your cylinder cover for rocker shaft hole elongation.  The aluminum is not very good as bearing material.

[bwaller]

motorhead if you enlarge that oil restrictor ID it'll be at the expense of your crankshaft lubrication. If everything was well cleaned on reassembly there should be plenty of oil to the top-end

[hymodyne]

blockage of one of those small passage ways on one side of the cylinders wrecked half of the rockers, their shafts and the cam lobes due to oil starvation in my overbore engine. some have discussed putting an extra oil feed from the sump up to the camshaft to counter this, although purists will insist that proper cleaning and rebuild and good maintenance is all that is necessary. It does amaze me sometimes, however, how engines so indestructible and reliable can become unnuseable via the introduction of such small particle matter...

hym

[bwaller]

Hym,

Maybe you're calling me a purist, not sure if that's meant to be good or bad, but if you are going to do any engine work then being meticulous about cleaning all parts before reassembly will ensure no small particle matter is available to block restrictors. There is no excuse otherwise.

These engines were designed to provide adequate oil pressure to the crank first and re-engineering the lubrication system willy-nilly is fool hardy. Improvements can always be made indeed. The external top-end feed on these 500/550's is one I believe, but isn't meant to improve oiling but to avoid potential leaks.

Now... have a nice day. 

[hymodyne]

Bwaller, my observation wasn't directed specifically at you; and in actuality even as it describes your maintenance ethic it should be taken as a compliment, inasmuch as over and over I find that Mr Honda got it right back then--all we need to do is observe the procedures prescribed in the manual and by good old common sense to make sure that these old engines still run well...

...you have a nice day as well...