Been doing my homework and downloaded "How To Select a Motor Oil and Filter by Fitch, highly recommended for other Newbys BTW.

My application is a little unusual so please bear with me whilst I elaborate:

Vehicle is a 1969 650cc Triumph Trophy motorcycle, my pride and joy and almost original, It does no short journeys and I ride it sympathetically, though

The std oil filtration system is gauze strainers in the dry sump scavenge pickup and another in the oil tank on the suction side, pretty crude you will agree.

I have fitted a Norton Commando spin on filter mount to the return to tank line, modified to accept available 3/4" UNF filters [std was 15mm metric thread]

Been looking for very high quality Fleetguard LF3460 equivalent, may have found it in the Amsoil SDF57 and hope that I have because premium filters are hard to find in Australia.

Running Mobil 1 5W-50 and appreciate the strengths and limitations of the oil but James Fitch's excellent work has got me wondering re how can I get SAE J1858 data on full flow filters ?

I realiase that my choices are limited with full flow filters, there is no room for an additional bypass filter, even if one were available in the small size required but I would be happy to import a dozen [box] of a better filter is they were available.

It would be nice to get even a 20% capture rate at 8 micron if I could.

I have run short of information guys, any assistance would be appreciated.

British motorcycles do not need good filtration, the leaking and constant refilling ensures a supply of fresh oil.

Dunno, maybe you are not the best of mechanics? With modern gasket materials and elastomers mine does not leak.

Or maybe you do not own one and never have ?

In either case it is probably best to remain silent rather than open one's mouth and remove all doubt etc.

In India you can still find the Royal Enfield and it is manufactured till today with the gauze filter. I have seen the best results with Mobil-I 15W-50, keeps the internal clean and engine much cooler.

Well, I understand your wish to increase your engine life by improving your filtration system. But please bear in mind that fine filters have a pressure loss, especially during start-up. This may lead to longer times of low oil pressure for yor bearings / camshaft. (I do not know your engine though.)
Do you happen to have the chance to measure the oil pressure after your oilfilter? It should be at least 0,6 - 0,8 bar during idling. Otherwise you may see increased wear because of boundary friction.

Agree with Callisa that a freer flowing filter is better (for various reasons though). On startup, however, would not the bypass valve over ride the filter restriction? I saw no difference between the 3 gallon per minute flowing John Deere filter I just pulled off and the Wix 7-9 gpm I ran last winter.

1 Bar approx 15 psi I think. Anyway, mine comes up to well over that quite quickly on cold start, even zero F. Idle is 21 psi hot with my preferred 10w40 (5w30 only got me 16 psi hot idle).

We are still talking about a 1969 650cc Triumph Trophy motorcycle. That's a different animal concerning oil pump and oil circuit design than a 4 cylinder inline Ford / GM / BMW engine.
Even the differential pressure loss of the filter bypass valve could be too high for the oil pump.

quote:

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Originally posted by Callisa:
We are still talking about a 1969 650cc Triumph Trophy motorcycle.

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Duh, of course. (slaps self up side the head). I have to remember to take my automotive blinders off once in a while. Thanks.