Oil filter selection

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Morning all !
I have some questions on oil filters which I would like professional opinions on.
I own an old Yamaha XS650 motorcycle - 4 stroke twin wet sump. As standard they just have an oil strainer inside the sump bolted to a small cast plate (about 6"x3")
I have found a clever mod on the web where by machining the plate and adding a block in the sump you can convert it to a conventional spin on oil filter.
So far so good.
I've done it and it works but I have some questions.
I want to make some more up for other XS owners so I want to find out a bit more before risking other peoples engines !!

1. In this application the oil is sucked through the filter. That means there's only about 10-15psi working - I have read the pressure drop across the filter is a few psi - anyone have any data ? For clearance reasons I would prefer the smallest filter can available (It hangs down under the engine) Would that increase flow resistance ?

2. Obviously It would be nice to have the best filtering available - say a Mobil1 or Bosch synthetic filter but it sounds like that would also increase flow resistance, maybe I should stick to a more open filter and reduce the risk of cavitation in the oil pump.

3. Can I get real data on filters from the manufacturers - ie on the bypass valve setting and tolerance.

4. Filter size I think is most appropriate has M20x1.5 thread and a can diameter of 69mm (2.72") Its used on a lot of Mazda's and some Subaru's - where can I find the standard tolerance on Diameter, It's important I don't open up the sealing land too much or I weaken the plate.

5. Theres a shorter filter available - Fits Yamaha Fazers - but it's slightly bigger diameter (about 1mm) - again I need to know what the maximum could be, Also is there REALLY likely to be any difference between a car and bike

6. I have a theory ! The bike is old school engineering , all roller and ball race construction, no plain big ends, so I feel it is more tolerant of lube problems, Certainly the engine is well known for long life , any comments ?

7. Would oil choice significantly affect performance? ie using an oil with a lower static viscosity. And how much does this vary from brand to brand ?

7. Am I doing the right thing or would I be better leaving it as it is ? Existing filtration is pretty much non existant, the sump strainer almost always bursts so does little, theres another smaller one after the pump which could be left in place or removed.
We are really only talking about old part worn engines here but it's pretty important to keep the bearings working as they are both VERY expensive and no longer manufactured.

Note UK Champion filter numbers for the cans I have tried are F129 (Mazda) and F307 (Yamaha)

Thanx for reading all this !! I would really appreciate some feedback.

Steve.
 
Here's my thoughts.

The system pressure is going to be the same whether the filter is upstream or downstream of the pump.

I don’t think cavitation is going to be a problem as the vapor pressure of hot of oil is low.

The bypass valve is probably going to be useless since most take more than 14.7psi to open. I’d use the thinnest oil you are comfortable with. Maybe 0w40 mixed with 0w30 would be best.

You should use the least restrictive filter you can find.

I’d use the Honda 15140-MM9-013. It’s free flowing and has lots of media. OD is 67mm and it has M20 X 1.5 threads. It’s 69mm long. Its bypass is 18psi which means it will never open but such is life.

I’d look at a bypass filter setup as an alternate scheme to what you’re doing.
 
Hi
Thanx for the reply
Is that oil filter spec a car or bike filter ? I want to look and see if it is available over here. - I presume thats a Honda OEM part.

In my way of thinking the system pressure is not constant but varies from negative before the pump, and maximum positive just after the pump. Like most automotive oil pumps this is a positive displacement lobe type, so It is probably easily capable of 100psi in theory, plenty enough to push oil through a restrictive filter placed after it. Bit as you obviously realise, it can't pull more than one atmosphere vacuum (probably nearer 10-12psi)
Normal system oil pressure is probably very low.
There are designs out there for conventional, downstream filters but they involve drilling the casings and running extra pipes which looks messy.
A byepass filter sounds like a nice idea - I presume I need to arrange lines to a remote can with a restrictor somewhere?
Thin oil might be a problem, the engine is designed to run on 20W50 plus the standard wet clutch plates dont like modern synthetics
Steve
 
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