oil pressure indicator

I feel the need to care that these is always substantial oil pressure at the crank of my 850 while it is revving hard. I was wondering if there is an easy way to fit a car type pressure switch, so that I can have a diode up next to the tacho ? If the switch operates at 20 PSI, then if the oil pressure fell too low I would know about it - could be a lifesaver ? I have never had the relief valve apart, and I wonder if there is already a replacement for it on the market.

All the pressure switches I've seen on Commandos are fitted in the rocker oil line , in between the feed banjos and cable tied to the head steady. I did this to one of mine and used the charge light as the low pressure indicator, as I figured low oil pressure warning is more important than charge status.
sam

What is the pressure switch which operates at such low pressures ? And if it is on the return line / rocker feed doesn't that mean it only senses what is coming back, and not what is entering the crank if the conical seal between the trimming chest and the crankcase fails ? I see what you mean and it is probably better than nothing. I will have a look at it.

Commando rocker are fed at crankshaft pressure so it's an ideal place to tap off to feed a gauge or pressure switch. If I recall correctly, Triumph rocker are fed by the return (scavenge) side of the pump.

I was not aware of that, I simply presumed it was the same as on most British bikes - off the return line to the tank relying on the slight back pressure differential . Thanks for that. I've got the Haynes manual and info about the oiling system is all over the place. I've got a spare set of crankcases, I will have a good look at them.

You might to look at something like this.

https://www.merlinmotorsport.co.uk/p/ad ... t-m-ops-35


I would have thought a gauge would be easy enough to fit and give you much more information.

I've had a look at the oil pressure switches on the web. Many have internal contacts that are 'normally closed', and some open at about 12 PSI. That is enough margin to be safe. A gauge might give more information than a simple diode, however I don't believe I would be able to read it during a race. If the diode lit up next to the tacho, I would certainly see it. There are some very nice digital oil pressure gauges available - I could not bring myself to fit one on what is basically a late 60s bike. I once saw a Kawasaki H1 at an historic meeting with full go-hart digital electronics on the top yoke, and thermocouples in the chambers - makes a joke of the whole thing. Back in the era we did not know what a silicon chip was. It is bad enough that they are hidden in ignition systems. There is one thing about the pressure switches - the threads are not long enough to go through the rocker feed union - makes it difficult to have the installation look respectable. I know it is silly, however that is important to me. I bought a brass cock and fittings to fit to the oil feed pipe to stop wet-sumping. I've never fitted it because it would look like such a non-genuine abortion.
I am surprised that Norton took pressure off the crankshaft to feed the rocker gear. This is the only old British bike on which I've ever seen it done that way.

This is what I mean by 'not looking quite correct' :

http://www.youtube.com/watch?v=0KOFvhUzug4

The switch I have is threaded into a T piece each side of which goes to the rocker feed port banjos via short lengths of hose. It isn't visible when the tank is fitted, not that that would bother me anyway.
sam

acotrel said:

....... A gauge might give more information than a simple diode, however I don't believe I would be able to read it during a race. ....

Click to expand...

I have a gauge on my BM race bike and you're right, it's hard to read during a race, but you just need to see roughly where the needle is, you don't need to be able actually read the numbers on the gauge. I got mine from a car shop, cheap as chips.

I've thought about using a T piece to hold the switch, it worries me a bit that I've only got that tube wired on. I wasn't aware that it was subject to full pump pressure. I'm certain I cannot read an oil pressure gauge while riding hard. I even find reading the tacho difficult, and that must be done on every gear change down fast short straights. In the past when I rode Triumphs , I always had a look at the indicator button as I finished each race, I suppose I could use a gauge that way. Or perhaps I should just buy myself a better hearing aid so I can hear the bang ?

If you throw the outer bit of the Triumph oil pressure reliefe vave on , if its almost in your line of sight , its about as simple as you can get .

Guage readings knowing where the needles are supposed to point . If thyre arranged needl vertical at the correct setting ( Redline ) You know if theyre NOT at the desired position .
A warning LIGHt for opoils a lot more use , as a primary warning indicator . With a high wattage bulb :lol: . As it migh grab your attention . As youre Dry Sumped , oil surge is hardly
going to be a problem . So overheated :? oil or a systems failure are avbout the only lookouts .

A custom bolt into the timing cover for the rocker feed , or brazeing a suitable nut or T there , for a ELECTRIC switch or sender , saves a pressureised oil line to fiddle with .
VDO & maybe a few other guages are deadly accurate . Most el cheapo ones would be indicative rather than exact .

The KROBER tachos were IMPULSE tachometers , as VDO does . So instantaeneously follow crankshaft speed - You can see the blip on the tach on ea shift , the needle hits the min & max rpm's
in that iota of time . You dont try'n read it , but you can see where its been , for recall when youre not so busy .

If you want to get the black & decker out ,

you could drill & tap into the oilway wher conveniat . Raceing bikes are supposed to have holes drilled and bits bolted everywhere . :|

I didn't realise that the top part of the triumph relief valve fits the commando valve, or does it require machining ? I might even still have one in my old nuts and bolts box with all my cycle thread stuff. If it can be fitted that would be a brilliant answer as I can avoid the extra electrics . With the Triumph indicator, it is common for the button to be right in if the motor is very hot. It should always be right out when the motor is cold. I think a total pump failure when the bike is flat out is rare. Is the conical seal between the timing chest and the crankcase actually conical or is it simply a fat neoprene rubber 'o' ring compressed ? That is what I am using and I've often wondered about the possibility of it leaking into the sump. You would still see oil returning to the tank.
I use the tacho off an RG250 Suzuki which looks as if its off a 50s Italian racer, it has a bit of red plastic tape stuck to it and as long as the needle doesn't go past the pointy end of that, the motor stays below 7,200 RPM. The tacho has the correct 'O' ring mount for the Mk3 Seeley frame and had the reversible gearbox on the back. I don't like looking down at it when the bike is flat out, everything happens very quickly - acceleration, braking and cornering. Sometimes I ride by sound.

The OUTER of the TRIUMPH goes on the INNER ( the release valve ) of the NORTON . Its all self explanetry as it only goes together thus .

The Gen u wine seal is a / BSA ones similar - ish . its a rather firm rubber .

You can feel the nip fitting the cover , should compress a few mm at least .

the Triumph indicator runs 3/4 out hot , most of the time . 1/4 out or 1/3 at the Traffic Lights . If its not out youve dropped the seal on the wood shaveings in the boat shed .

Are you telling me that the Triumph outer actually has the correct thread to fit the Norton inner ? Well, I never ! - How long has this been happening ? I didn't know there was ever any sort of standardization in British bikes. What is the correct name for the conical seal, is it available as a normal auto part from the bearing companies ?