Question for the Anglo-bike guys...

[Rusty Bucket]

I am continuing the work on the CB450 Fritz and I bought from Roy's a few years ago - using only the very best of what's free around my place.  While making two naughty clutch baskets into one nice one, I noticed the centrifugal oil cleaner case, which runs on the end of the crankshaft on this bike, is half filled with a hard, grey clay-like substance I haven't run into before.  The bike has been sitting a very long time, and maybe that explains it somehow; there doesn't seem to be a high metallic content in the material, but it is grey as I say, and impervious to every solvent and strategy except a screwdriver.  When you guys crack the sludge-trap on one of your old cranks, what is the material inside like?  Is it black and coked-up, or?

[Theo]

The only centrifugal oil filter I've had experience with was on a Fiat 850 car engine. It too was filled with grey, clay-like material packed so tight that it was dry and required chipping out in chunks with a small scraper. However, what remained after scraping did wash out with regular shop cleaning solvent and some vigorous brushing. No evidence of any engine damage other than burned valves which would not likely explain the crud in the filter chamber. I suspect it was just the result of a very long absence of service to the engine.

[Fritz]

Noticed that when the engine had been sitting around for many years....the Goo was Hard and chunky......Unless as from some pics I have collected...  -  the engine had been run recently,  it was a little Gooooeeeeeeooorrrrr....

*

*

*

*

[Rusty Bucket]

Right! Exactly that colour!  So that grey clay can come out of what is otherwise a normal, if long unserviced, engine?  That's a relief.  I guess I am unnerved by it's similarity to the fine paste to be found in the oil pan of an engine which has eaten a cam lobe, and/or the cam followers - though that grey is more unsurprisingly silver with the expected high metallic content.  I guess I didn't try motor oil and heat as a solvent, or maybe the stuff wouldn't have proved so resilient...