Hi,
Another oil thread !
Still happy with the 10W50 or 10W60 Castrol synth. But, as I mentioned a few years back, the engine should be adapted to take this oil, which I did (modern gaskets, paper oil filter and in my case a higher volume pump and bigger oil bores where applicable).
Over the last years I shifted a bit more into the CB450's, there the oil issues are more demanding because of the torsion bar valve springs (the pressure between cam and follower is very high the first few tenths mm of lifting the valve due to the torsion bar spring characteristics compared to “normal” springs.
And yes, I also saw a lot of damage in older engines, due to oiling issue's but it's hard to tell if that's because the oil quality or lack of maintenance.
I thinks original owners lost interest in these bikes, sold them for cheap to young guys, and you all know what young guys do to cheap bikes. The ride like they stole them and no money for any maintenance at all.
I also have a first owner CB400F, bought it with 86.000 km on the odo. The bike was cared for like a baby, and maintained very well. The only reason to take the engine apart at 106.000 km was that the cam chain couldn’t be adjusted anymore. The original owner always used Castrol 10w30 mineral oil. The engine was spotless, even the crank bearings were within assembly specifications.
Jensen
engine oil
Having just taken three crank shafts apart, and finding all the crud in the crank pins/center bearing recesses, I wonder if these areas act like a centrifugal filter on a smaller scale: they rotate at high speed, the same as the filter. It would seem to me that a detergent oil would keep the impurities suspended, and not be deposited in these crank areas, eventually building deposits and starving those areas of oil. In a recent post, I showed a photo of what I removed from the crank pin, after removing the aluminum plugs. How could the big end of the rod get oil with so much swarf in the rod pins? And how much of this swarf, from a bike that had sat for a while, was slowly breaking loose with hot fresh oil, and circulating around the center crank bearings and rod bearings? Was this build-up a result of ND oil? Since I did not know the history of these cranks/bikes, I'm glad I took the cranks apart for my rebuild.
Yes, the proper oil will be a consideration for my rebuild, now that I have seen the effects inside the cranks in an engine that has no media filtration for the oil. Just my observations... Dick
Dick
Pretty much the same findings and thoughts I took from my crankshaft didmantling saga. The interesting thing is that the radii of the crank pin and the oil slingers for the big end are actually greater than the radius of the oil slinger hence more force to spin out the particles. There has been some clever design. though in the design of the big end sludge trap and the feed from teh slingers in teh crank web. The oil feeds to the big end are placed away from the place that most of the sludge gets trapped so the crank will still be lubricated even when there is quite a bit of debris in there. The stuff in the crank web is almost invisible until you poke at it with a sharp tool.  The problems occur when the crank is sat for years and then put back into an engine. That stuff can come loose under the influence of hot oil and do its worst on your newly rebuilt engine. All my cranks will be stripped and cleaned for this reason. G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
in my more limited experience with cleaning out centrifugal filters (I have never pulled a crankshaft apart) is that they contain very fine metal particulate, not the carbonaceous stuff shown in the picture. If the crank pins were accumulating material in the same way I would expect it to be the same material.
What is the black material like? Is it hard or soft or gooey etc.? If it were hard and crunchy my guess is that it has been baked by high temperatures but I can't think of any reason that the crankshaft would be particularly hot. Certainly I have never seen anything like this around the exhaust valve guides which one would expect to be much warmer. Any thoughts? Tim
If you could collect that volume of metal in the centrifugal oil filter the engine woud be dead. There may be a little metal in there but most of this stuff is just burned or otherwise decomposed oil (blown by the pistons), bits of clutch friction material. There is always some leakage past the pistons and the underside of the pistons are cooled by oil thrown off the big end bearings. If the pistons get very hot then the oil will bake on there and maybe decompose. The material varied from soft black putty to hard crusty carbon depending on whether it is bathed in oil recently. G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F Hi,
The stuff is black sludge. It's a relic of old oil, being there for many years. Once hardened, very hard to remove with chemicals. Only removed by mechanical handling. Believe me, I treid in many different ways, including very powerfull ultrasonic baths. Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
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