Topic: Oooh, that's not good... lots of metal in my oil filter

[Tugboat]

I've been planning on using the bottom end of my 750F along with the top end off a 750K after bending a couple of valves. Long story... So I pulled the oil filter off last night in preparation for removing the old motor from the frame and this is what came out. Looks like I'm splitting the cases now. Bummer. But could it be that the filter caught most of the offending particles? It wasn't like this at all when I pulled the drain plug - that oil didn't seem to have any metal in it.

[Gordon]

Dang!

First thing to do is put a magnet to it to see if it's steel or aluminum.

[Tugboat]

The difference being?

[Gordon]

Aluminum shavings = not always something critical. 

Steel shavings = almost certainly something critical. 

[MCRider]

Aluminum = pistons, cam bearings (still pretty critical IMO)
Steel = cam, rockers, main bearings, trans parts

In either even its gotta come apart.

[Tugboat]

Well I'm replacing the top-end entirely. Pistons, jugs, head... Pulled 'em off another '76 750 motor and am just going to swap 'em out. When I bent the valve I had to drive the thing like 45 miles back into town and it was only running on 2 cylinders by that point (but still running!!!!). The head & pistons and whatnot are surely trashed. My main concern is whether or not that could be evidence of bottom-end damage since I haven't been planning on splitting the cases.

[MCRider]

Well I'm replacing the top-end entirely. Pistons, jugs, head... Pulled 'em off another '76 750 motor and am just going to swap 'em out. When I bent the valve I had to drive the thing like 45 miles back into town and it was only running on 2 cylinders by that point (but still running!!!!). The head & pistons and whatnot are surely trashed. My main concern is whether or not that could be evidence of bottom-end damage since I haven't been planning on splitting the cases.

That goes back to the magnetic suggestion. But regardless of steel or aluminum, I couldn't be comfortable without at least a disassembly, thourough cleaning, and inspection of the oil pump. Not much you can do with an oil pump if the rotors are all nicked up as few parts are available. Find a low mileage one on eBay is best bet.

[Gordon]

Aluminum = pistons, cam bearings (still pretty critical IMO)
Steel = cam, rockers, main bearings, trans parts

In either even its gotta come apart.

Like I already said, "aluminum = not always something critical".  Didn't say "never" or "rarely".  Could easily be the cam chain is so loose it's rubbing the inside of the tunnel.  A somewhat common cause of aluminum shavings in the oil, but not a critical failure.