A few years ago, I wrote something about the spinner filter. The main difference between a spinner filter and a paper filter is that the filter function of a paper filter is a simple function of the particle size, while the filter function of a spinner filter is much more complicated, and one of the many parameters are the oil itself.
The principal of a spinning oil filter seems to be simple but isn't when you look at the details.
The idea is that by centrifugal force particles are driven toward the edges of the filter where these particles will accumulate. Once in a while you clean the filter and the process starts over again.
The centrifugal force on the particles is depending on the circular speed of the filter and the weight of the particle and the distance of the particle from the center.
Fc= m*w2*r
Fc is the centrifugal force
m is the mass of the floating particle
w is the circular speed
r is the radius or distance from particle toward the centre
In this particular case (honda 305) the w (circular speed) is not constant, it changes linear with the rpm, it's influence in the formula (thus on the particle) changes with the square of that.
The first experiences with full synthetic oil (5W20) I had were with Honda SS50 / CD50 engine.
I experienced that, when I used the oil, the engine was cleaned within a few hundred miles, and everything what was lying around in the cases would accumulate in the spinning filter (part of the clutch). So, in this case the spinning filter is working fine.
Later I experimented with full synthetic oil on larger engines (CB72) and found the same results.
The first conclusion was that the spinning filter works fine with full synthetic oil, so I started using this oil in a rebuild engine (and a new oil pump). Every 1000 km I cleaned the spinning oil filter and every 4000 km I changed the oil. After 12.000 km I was curious how the internals of the engine would look like, so I decided to open it up. Everything was in as new condition and measurements after 12.000 km where comparable with the initial values before installation.
So nothing wrong here ? Yes and no. I also inspected the oil pump and I found wear at the oil pump gears (as stated it was new 12.000 km ago). I checked with the oil pumps used in the
small displacement engines and there was no sign of wear. Time for looking for differences.
It took a while, but in the end I found the few reasons for the wear on the oil pump in the CB72 engine. The mean reason is the difference in construction between the oil filters, and I will explain with the formula above.
When I compared the values in this formula for the two engines I found a few differences.
Mass off the floating particles in both engines are (assumed) the same.
The radius of the area where the particle is (toward the centre) in the centrifugal filter is depending of the radius of the filter itself, and here I found a difference in construction. The radius of the small displacement engine is a little bigger then in a CB72, so the force on the particle is higher.
The circular speed (w) is depending on how fast the filter is turning around, and here I found the also construction differences. In the small displacement engine the oil filter is attached to the clutch (part of the clutch) and this clutch is directly attached to the crank. Therefore the speed of the filter is the same as the crank speed. In the CB72 it’s not directly attached to the crank but the power is transmitted by a chain. The chain gears on the crank and oil filter would be the same there isn’t any difference, but this is not the case. The filter runs with a higher speed then the crank, not much, just a little (24/22 teeth).
The difference in driving styles are also responsible for a difference in speed of the filter.
Since the crank speed is depending on the rpm, the rpm of the engine dictates the force (Fc) on the floating particle. I ride the small displacement engines with much higher revs as the CB72 engine, because of the lack on power at certain speeds. Where I tend to run my CD50 at a constant speed of 55 km/hour the engine is running over 7500 rpm. I calculated with an average of 7000 rpm. At the CB72 I’m not running this rpm as often as I do on the CD50. I calculated with an average rpm of 4500 for the CB72.
So, when we look at the impact on the force on the particle, with the data above :
Fc for the CB72 compared to the Fc for the CD50 :
Mass of particles is the same, so mcb72 = mcd50
Radius of the CB72 is 0.8 of the CD50, so rcb72 = 0.8 rcd50
Circular speed of the CB72 is 0.64 of the speed of the CD50, so 0.64 wcb72 = wcd50
The construction factor between CB72 and CD50 is (24/22), so 1.09 wcb72 = wcd50.
When filled in :
Fc cd50= m*w2*r and Fc cb72 = m*((1.09*0.64)w)2*0.9 r
Fc cd50 = m*w2*r and Fc cb72 = 0.43 m*w2*r
This means that the centrifugal force on a floating particle in the CB72 is a halve of the centrifugal force on the same particle in the filter of the CD50
A full synthetic oil is a very powerful detergent, it will clean the engine very good and drop the particles in the filter due to the above explained principal. The very small particles (like cool) are not filtered out by the filter, but don’t do any harm to the engine either.
But if the detergent power of the oil exceeds the influence of the Fc on the particles in the filter, these particles will not be held in the filter and start floating around in the oil.
This means that when the running speed of the engine is low (rpm) the oil starts cleaning the filter itself, and this is probably why I found wear to the oil pump gears. In the breaking-in process I never push the machine to it’s red line, so dirt collected in the filter was washed out and went through the pump.
The conclusion of the oil analyse was that there where a lot of particles floating around in the oil, which should be filtered out.
I'm old and wise enough not to mention my preferred way of filtering, but the above is just a thought.
And the question about Cappellini, well, I know the Italian company is reliable and knowledgeable (but it is Italian, and not German if you know what I mean).
A few years ago I bought a Cappellini oil filter setup for my CB450 bomber. I was pleased until the moment the filter element tore while in operation. Remember, when something like this happens, there is nothing to stop the dirt from doing it's damage !
I immediately dismissed the filter and developed my own setup based on an another, more reliable filter element.
Jensen
Cappellini Products for CB77...
Jensen, thanks for the great info. So if one were able to source a 'better' filter (don't know if the K&N or the like is 'better' or not), would that Cappellini setup be worthwhile?
Yeah, I know what you mean about Italian vs German -- my 'people' are great at making things beautiful. Mechanics, well maybe not necessarily as good. Vince, not meaning to be personal, and no offense. I meant it's all about the testing procedure before selling something. The choice of material and finishing is superb, really it is.
A filter element for oil is something different than an element for air, something to do with fluid dynamics versus behavior of air, but that's another story. Meanwhile, one is not better then the other, and the other is not better then the one, in the end it's all about the oil you use, and how you use the bike. Using it as a tourer (like a dream) I would go for an static filter setup. But when I use it as a SS (supersports) there is not much to say. But I do know that not using the spinning filter setup you will increase the power on the rear wheel and make the engine less noisy. But after all, isn't that the charm of any given classic bike ? assembly of Japanese motorcycles requires great peace of mind (Pirsig)
No problem Jensen, I'm totally fine with poking the mechanical 'designs' of the Italians. For example, I've always lusted after a Lamborghini Espada, but I'd never buy one as I'm sure beneath all that gorgeousness is an Italian mechanical nightmare! So no offense taken at all -- I'm sure the best car in the world would combine the aesthetics done by Italians and the mechanicals done by Germans. Mind you, I think one of the most beautiful cars on the road today is the Porsche Cayman, so go figure.
I think if the oil filter kit was simply a 'plug-n-play' conversion, then I might consider it. But the part that kinda has me concerned in their eBay listing is their recommendation to use one of their higher capacity oil pumps. Well that's another $400. So combine that with the oil filter conversion kit, plus my paying John $75/hour to install it, then we're probably up to $800. And for how much benefit? And is that benefit worth the cost and trouble?
oil filtersHello everybody
Dont know if this is very relevant but I have ran a Cappellini paper element conversion on my CB350 engined racer (using Castrol R30 or equivlent). I would say it has been a sucessfull modification, as there does not seem to be the fine scoring on things like the piston skirts etc. though the main thing is convenience (perhaps I am just lazy). I should point out that this is on a race bike so not so much mileage but most of it at high revs. and I do run air filters on that as well. Early on I did have the same problem as Jensen with it the filters getting holled we modifed the outlet with a flow deflector (sounds technical but actualy just a bit of feeler gauge). I dont think this would be a problem on the CB72/77 ones as they are fed in the end and not the side ?. I know the 72/77's dont have much pressure but I am sure that must be enough for a paper element system, plenty of other roller bearing crank bikes use them and hopefully some others on the site may have some experience to help, I know of at least one 77 racer that uses them (externaly mind you and probably with a larger pump ?). Not much help from me then, if you have the money it seems like a nice idea but probabaly not actualy needed. Oh. by the way whats all this nonsense about German engineering and Italian styling on a site dedicated to Japanese bikes, plus it was Enzo Ferrari who said the most beautiful car in the world was British ! mind that was a while ago. Gordon SAFOJ And if you want to see some of the worst, unreliable engineering you can find, take a look inside a German-built Kodak Retina Reflex camera of the 50s and 60s. Nice to look at and great while they are working.
Having rebuilt around 50 of them I'm glad nobody wants me to anymore....... And, most of the cars I see broken down on English Motorways are Mercedes. Those Capellini bits do look compelling, though, don't they? How about a plain bearing crank and a proper oil pump in a CB77, Jensen? 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
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