can anyone tell me what the pressure is supposed to be, say, at idle and at full revs? The button indicators are great if you have them and if you are dead set on originality, but for daily use it seems that a regular oil pressure indicator would be just as useful (although obviously not original). But I seem to recall that M20 oil pressure at mid-revs is in the single digits (in psi terms) so an ordinary automotive oil pressure gauge, which goes up to 100psi or so, would be useless, since the needle would probably be still on the peg at full tilt of the M20.

email (option): jonny.rudge@verizon.net

Hi John, The spring loaded anti drain valve lifts off its seat at 7psi.(assuming a standard spring is fitted)Up to that pressure the pump is operating against a 'blind' system. Beyond that point oil pressure is not really relevant as with an open roller big end it is not a pressurised system as such.. Oil volume at various engine speeds is more important....Ian

There is no real need to supply a high feed pressure to the big end, as it only needs to be pumped at low pressure to the end of the mainshaft and then centrifugal force from the revolving flywheel creates a higher pressure to the big end than the pump would ever do. The mere fact that it is a roller big end would not allow a high pressure as the pressure would leak out of the big end between the roller bearings,so as Ian says it is the volume not the pressure that is important.

email (option): davmax@ntlworld.com

And for those reasons stated, Pre war Triumphs fitted oil pressure guages to their range with a very low reading face for the sigles with roller big ends. Max 20 lbs I think. But a much higher reading for the twins with shell bearings Again I think 90 lbs. Ron

email (option): ronpier@talk21.com

Ariel, and no doubt others, removed oil pressure gauges from the singles after a rash of warranty jobs resulting from worried owners taking their bikes in to sort out 'low oil pressure problems'. Once the gauges were removed the problems ceased..
I guess too much information is not helpful unless you know exactly what the system should do under varied operating conditions...
I think many modern manufacturers should think about that...With multiple adjustments to front and rear suspension, electronically controlled 'riding modes' and even variable power settings on the latest Ducatis..how many users are actually able to determine what is the optimum setting for a given set of conditions?..Ian

That's what I thought, a 20- or 30-psi max oil gauge should be usable. They only run about $30 (but, of course, need fabrication of the oil connection and mounting hardware, since I doubt that anyone manufactures those pieces).

Ian: most car and bike manufacturers are removing information that our generation would have found useful (such as pressure and temperature) in favor of decision making by computer, and add useless information because it looks "cool." (What use is a tachometer when the car has automatic transmission and/or an electronic rev limiter?) Although this is yet another example of "dumbing down" it seems to be the norm these days, in all aspects of daily life. People simply want machines to fill in for their lack of knowledge and/or skill and blindly assume, for example, that a 200hp bike or 500hp car will get them there faster whether or not the rider has the appropriate skill.

email (option): jonny.rudge@verizon.net

I am very critical of modern bike magazines which consistently make no mention of the implications for reliability, longevity and high maintenance costs resulting from layer upon layer of electronics.
Most of this stuff is irrelevant when it comes to riding a bike and the ability to enjoy it at the level of a piece of machinery.
However, it appears the world is now 'gizmo' mad and deems all of this a basic requirement.
There are some great examples...an electric toothbrush that requires batteries so that you can avoid the massive strain of moving your hand..washing machines with 15 programmes..when all you ever use is 2 of them. Digital cameras with so many functions you'll NEVER learn them all...even cars that now include a 'driver fatigue warning' function (VW).
Technology is great when it is performing a meaninful, necessary and beneficial task (the automatic washing machine?) but when it is applied for the sake of it being there in my opinion it merely represents poor design...Ian

when i ask for a mobile phone that just a phone no camera game and other gizzmos they though i was crazy

Continuing to wander vaguely around the topic, i recently did a 9 day ride on my modern bike and was crazy enough to keep on riding for the 1 1/2 days when it rained. Result LCD speedo display now has half the characters missing due to water leakage. Manufacturer says their gear doesn't leak, so my problem. If the LCD gives up altogether the bike will become a static display due to antitheft smarts in the electronics.
The rebuild cost on my 16H chronometric is now looking very cheap.
Oh and the 3 Norton Commandos i was riding with didn't falter in the wet