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[Seabeowner]

CB500 shop manual shows oil flow fairly clearly. Oil enters outside filter and exits via central bolt.
Looking at the centre bolt there are 4 holes that must be exposed above the filter when it is in situ. These are the 4 furthest from the crankcase. There are 4 more holes that must sit just inside the centre of the filter and these are blocked by the valve and spring up the CENTRE of the bolt, so that if excess pressure is built these 4 holes are exposed inside the filter and hence oil flows from the top 4 to the lower 4. The oil has now bypassed the filter, and can then enter the 6 further holes towards the threaded end as normal where it enters the galleries. Crisis averted...maybe. Sorry it's long winded.

[Trigger]

A few pics of 750 and 500. The oil leaves the pump and enters the oil filter housing on the outside. The oil enters the four holes at the top of the oil filter bolt, as the pressure builds up the oil pushes the spring down and exits at the next set of four holes.
The 500

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The 750

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[K2-K6]

Many different types of filter exit from the centre,  it seems more common that way generally.

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As above most car cartridges are that way. Think it's partly because of more surface area outside and so longer interval before blocking becomes a problem. Also,  pressure on the outside of a tube is easier to resist than the opposite with the same material's spec, so with both considerations you can reduce the filter size and still maintain the flow required.

Both fuel and air filters usually have outflow from centre generally if arranged in a loop configuration.

[Seabeowner]

A few pics of 750 and 500. The oil leaves the pump and enters the oil filter housing on the outside. The oil enters the four holes at the top of the oil filter bolt.

Surely if the oil enters the oil filter housing on the outside it simply flows through the filer. (unless it's blocked). It doesn't need the 4 holes at the top except when the pressure across the filter exceeds the spring setting.
Pressure alone will not open the bypass valve, only pressure drop across the filter.

[hairygit]

That's the whole point, if the filter is severely restricted or blocked, the exposed holes allow oil in the force the bypass valve open and flow down the bolt to the engine. If the holes weren't there, and the filter was blocked, how would oil get to the engine??

[Trigger]

Nope, the oil is under pressure from the oil pump (where the first pressure valve is) to the outside of the filter and if there is too much pressure then the oil under pressure enters the holes in red and exits through the next set of holes by compressing the valve and spring 


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[K2-K6]

There's always a pressure drop as you go through the system else the oil wouldn't flow.

The leak down via crank bearings and cam supply etc is what allows space for the oil pump to push volume,  it's only pressured because the bearing design allows for a controlled leak down as the engine's designer wanted,  which in turn (combined with pump capacity) gives the desired replenishment rate to each bearing location and type.

The oil will simply take the path of least resistance. If the oil bolt blead valve is set above the resistance offered by a filter in good condition,  then the oil's easiest route is through the filter material. If that becomes more restrictive to the point it exceeds the blead valve resistance then the easiest path is that through the emergency bolt holes.

The above has to be lower than the oil pump's own relief valve though as you'd get a non supply through that route being opened.

It's the same as any pressure relief valve though,  in that you can design it pointed in either direction. This one is just used as an exit from the filter housing as it exceeds the spec it's designed to if the normal operation is impeded by the filter material being blocked.

It's right to say that it is going to a low pressure area though as the bearings are inheritently leaky so if supply slows down, the pressure will drop accordingly. That's why the oil light would come on if you reduced supply volume.

[Trigger]

Can we all agree that the magnets will work 
A magnetic oil filter bolt would work much better than a magnetic sump bolt, me thinks 

[K2-K6]

Oddjob, as you say it's something that's so reliable you never really have cause to do anything with it other than when you replace the filter during service.

Trigger,  I'd say sump was preferable just so anything you catch hasn't had to go through the oil pump,  both sides of it and also expose the leak back valve,  plus possibly the pressure relief valve to bits that may degrade their operation.

You're going to get most of it during run in of new bores as you've pointed out "sump marzipan" (well that's what it feels like) which is going to diminish fairly quickly when rings etc have completed lapping.

Less interaction on the 400/500/550 though.

[royhall]

OddJob has an engine with 263,000 miles on it without problems. Just how would magnets enhance that. We have managed nearly 50 years with nothing other than a magnetic sump plug to help things, and loads of engines go over 100,000 miles without issues. Surely that's why we change the oil so often, so with magnets we can go 5000 miles between oil changes then. I think not. I'm not really sure what problem this fix is fixing.

[Trigger]

The magnets is helping collect crap while running in after a re bore  As K2-K6 has said, the worst amount of metal in the oil is from the meshing of new gear box cogs. All these new parts have sharp edges which need smoothing and as a result the engine could suffer damage from these new parts.
I have been in so many workshop where the mechanic will remove the oil filter housing to change the filter and not clean the housing before replacing the filter. And as Oddjob stated, ignore the washer, stuck to the filter

[K2-K6]

royhall,  agree that it's al very competently designed system and seems to serve the purpose well but oddjob's high mileage example just shows the potential and not necessarily the aggregate of what happens to all the examples. Plenty out there that get nowhere near that total without significant wear problems,  for whichever reason.
And we don't know what level of wear is in that example to make it definitive.

Reality is that you're going to get something resulting from the initial wear of new components,  question is how is that best delt with. I think it's something that's worth debate to see what the combined knowledge and experience on here throws up.

My feeling is that I'd rather not push it through the oil pump if that were possible. It looks like the filter will catch it but we don't know the micron size of the debris and if it has the potential to pass through the filter which appears to be around 10/15 microns.

Also likely that if we stood in Trigger's position then a more concerned view is apparent as most engines going out are rebuilt and fall into this category. I don't know the "warranty" position that's taken but any additional precautions can only enhance that type of work in delivering to clients.

[matthewmosse]

I would hazard a guess that running in  can mark the difference between an engine getting to 250,000 miles which is roughly where my 500/4 got to with its sidecar, hard to say when the clocks have died twice and its been round the clock as many times, and yet I have bought cb 500 and 550s that show 35k on thr clock and wear on seat, footpegs etc makes this seem genuine and the engines are totally goosed, right through destruction. I would think the odds of many cb500 or 550 bikes going round the clock are fairly low, bikes tend as a rule to not cover massive milages. So basically I think trigger is right, controlling that swarf from running in is likely to be key to long engine life. My high miler bike has less engine wear than bikes on a quarter the mileage and in my ownership it arrived with oil like tar, already with 60k on the clock and a sidecar so constantly worked hard. Seems the only thing to explain the fact it got there is that it was run in hard.

[paul G]

found these which covers the flow 

[Raymond_Y]

Magnets in oil systems are common place in aero engines, especially the piston engines of the 40s and 50s and the early gas turbines.  Their main purpose was early detection of imminent failures, but they also collected a lot of the fine crap that the filters could not catch, which has to be beneficial to any plain bearings in an engine. It is strange that people think that filters catch everything.  If they were designed to do that you would need a massive oil pump to overcome the pressure drop resulting from trying to push oil through such a fine filter.
Modern aero engines still have “chip detectors”, as they were known, but they are now linked to software that can interpret was is on the detector.  In some cases they are so sensitive they have to be switched of for the first few hours of running post build.

Raymond