30W Non-detergent - Or is there something better?
Hi,
Indeed, these engines do have roller bearings, except for the contact between rocker and camshaft, and the transmission itself (gear to gear). Cooling the air-cooled engine, especially the cylinder head, is one of the most important tasks of oil in this case, the total volume isn’t helping either. For this reason I modified the oil pump (more flow) and put an oil filter in for filtering out the junk (I took away the centrifugal filter), and added some extra cooling area and oil volume. When I disassemble any used CB72 engine, I see a lot of burned oil. Parts that are “infected” are the underside of the piston, small end, piston pin, valve stem and valve dish (don’t know if this is the right word, but I mean the area of the valve inside the inlet and exhaust ports). The two possible conclusions are that either the oil used in these engines wasn’t up to these temperatures, or / and these parts weren’t cooled down enough. However it shows that the temperatures of these parts are above 180 degrees, and that is hot. Either way I can use an oil which is capable of withstanding these temperatures over a longer period or /and pump more oil to these places, to cool down these parts. I decided to do both, using a synthetic oil, and supersize the flow. Btw, I disagree with your opinion (CL77now) on the centrifugal filter and detergent oil. Yes, they work together for 95 % of the range, but the forces to hold small particles in the filter are overcome by the oil which is flowing through the filter at low rpm’s (idling). Yes, it's an oil thread teazer, and that's all it is, no religion here. Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
i did not mean to imply the Centrif. filter is good or even effective (on each pass through) no way.
BTW some air craft use this filter type, for many good reasons. (sorry for bad key pounding) just that its presents (Centrif filter), don't mean i can run with out detergent oil. your why is better but the pump is not a real pressure pump and real filters are hard to pump through. this is an irrigation pumps system and the centrif. filter matches that idea. the 1000 mile oil changes is the other. if i could run a "Pure0ne" filter in all machines I would. sub micron.. got the impression that one must run non-detergent oil so the centrif filter would have something to catch. The centrif catches things , no filter catch infact a typical filter lets by 40micron sand. and the centfi will catch lots of that. in fact most if the input is slower that the catch. see? air filters let in lots of sand of a all sizes. you see it at rebuild time (in the corners) and the wear marks. cheers. CL77 99% done on mine.
For Sale, Yep, It's an OIL THREAD. Lots of anecdotes and personal opinions and not a lot of facts to work with. :-)
SAE papers are obviously not of any value for some reason and "reasoned logic" continues to hold sway. An oil engineer recently published his opinion and that was that oil temps should be above 212 F to boil out water and that 180 was a normal acceptable level for continuous operation and that peak temps under the piston would be 50 degrees higher. That was for aircraft engines where things get really hot when they trim for lean cruise. I personally like to see temps less than 230 (240 max)on the gauge but on a small motor with frequent changes that's not a big problem if they approach those numbers. Synthetics can generally stand higher temps before they break down and 260 is fine for them where 240 would be a max for dino oils. Synthetics offer no advantages that I can think of under normal street operation but have a higher margin of safety for hard riding conditions or motors running at less than perfect trim. So it's dino oil for run/break in and keep your bike properly adjusted and change oil frequently and it matters not a lot which oil you use.
Hi CL77Now (what is your name ?)
I can assure you that the CB72 oil pump is capable of pumping through an oil filter, don't forget that it is a gear pump, and when within spec's, good for creating high pressures. I doubled the flow, just by adding an extra set of gears, plus some work on the pump itself. When you say 40 microns, what efficiency's are you talking about ? there is a huge difference between 20 % and 99 %, also in the distribution of the efficiency of different sizes of particles. I use two filters (doubling the active surface, and thus lowering the needed pressure difference), and it works fine. I tested these filters myself, and found out that these filtered out 20 micron parts with an efficiency of 70 %. A centrifugal filter, like the one used in these engines, filters not to size, but to weight. It 's efficiency depends on the weight distribution of particles, and that doesn't necessary mean that the big particles are filtered out. Next to that, the weight distribution that is filtered out is also depending on the rpm of the engine. For this reason I added a very strong large flat magnet (neodymium) to the oil filter set up, which "filters " out the smaller metal flakes and particles. Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
Hi Teaser,
In case you do not ride it frequently, you better start using a synthetic oil, especially for protecting the cams on the cold start. It's a fact that synthetic oils do "attach" much better to metal surfaces over longer periods. What kind of facts can you endorse to stick with a mineral oil ?, or breaking in with a mineral oil ? In an older thread I asked for some dyno results to endorse the" facts" about these carburetors and the air/fuel ratios but ever since I have seen none, from no one. Yes, it's an oil thread, not a religion, but a thread that should be based on facts, just like the air / fuel ratio's. I did measured them, the rest is speculation. Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
YA GETTIN PUSHY AGAIN JENSEN.
Mello out please. ........lm
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