Topic: Metal in my oil: Now with pictures.

[sparty]

Gentlemen,

I now have a few digital pictures that I'd like to share.  I dropped the oil pan and this is what I found.  I also included a picture of the old oil filter and some of the oil that drained out of the oil filter cover.  By the way, my bike is a 1972 CB750K2

Here we go:

[sparty]

Here is the second set of pictures.

Round two:

[HondaMan]

Does it run? You haven't mentioned if there are any unusual noises around the engine, so it's guessing time... 
There are only a few things in a K2 engine that could come loose like that and stick to a magnet. These would have to be steel or iron pieces, and that list is:

1. The steel plate inside the cam chain slipper tensioner (goes down the front side of the cylinders, wears a lot). This can grind away little pieces over time. The shafts that hold the cam chain's 2 rollers are steel.
2.Rocker arms and shafts are steel.
3. Cam, crankshaft, rods and wrist pins (and their clips) are steel or cast iron.
4. Trans gears, shifter fork and drum are steel.
5. Ball bearings and their races are steel.
6. Mainshaft, countershaft and final drive shaft are steel.
7. The clutch housings and their plates are steel-based. These would be visible from the clutch cover side.

The pieces don't appear to be chain chunks, but you would have heard them by now. The primary tensioner looks in good shape, so those chains are likely OK.

[Boomologist]

Those are some large chunks of metal. I would be concerned that some of the finer pieces may have made it into the oil pump and stuck the pressure relief valve open.
Does the starter work properly without any unusual noises?  Sometimes when these engines are badly out of tune the starter will take quite a beating and can shed metal.

[Raul CB750K1]

I found a big chunk when dismantling my engine. The only thing I could think of was a gear or sprocket tooth. Never found what it was, not even a gear dog. Probably somebody before has abused the tranny. I would say clean the mesh filter -looks great in my opinion-, adjust the tension and run the hell out of the bike until it gives up.

Raul

[superchode]

heh. i only wish i had that much metal in my sump... looks like the bottom of a lathe down there.  had a torn oil pump filter to go with it, too.

all one can do, in my opinion, is correct the things which may have caused it, flush it out, put it back together and ride.

[sparty]

HondaMan, Boom and Raul,
 
Thanks for your input… The bike ran fine before I changed the oil.  The starter was/is fine.  It seemed to make the “typical” air cooled noises. There were no rattles, pings, etc. to worry me.  If the cam chain was rubbing the cylinder head wall(s) it didn’t make itself known.  Or, I am just too much of a newbie to notice.

The metal pieces in the bottom of the pan are actually smaller than they appear in the picture, the picture is a bit of an illusion.  Anyway, the PO had a 17 year old son who learned to ride a bike using the CB, I am sure that the tranny gears got some abuse from him, that would explain some of the metal “chunks”.  I also did find a perfectly, but ultra-tiny, round piece of metal like a bearing, but it was only one.  Hmmmm?  
I’ll be taking off the cylinder cover and inspecting the cam chain unit.  I’ll have more pics by the weekend.  From what I am seeing and with your input I suspect that the cam chain is loose, and the PO’s kid may have banged up the tranny, clutch and gears a bit.

[andy750]

Dont forget to flush out your oil tank with gasoline (as likely you have some metal in there - even with an oil change).....no point in cleaning out the pump etc and not doing this....

cheers
Andy in Boston