oil pressure switch in Commando electrical system

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xbskt

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Hello to all,

I still need to draw up a diagram but am looking for input on oil pressure sensors on a Commando. I want to put everything except ignition on the load side of a relay that is controlled by an oil pressure switch that closes when it sees running oil pressure.
This will give maximum voltage to the ignition and then when up and running call in the rest of the electric circuits.
The question is where to fit a switch in the pressure side of the oil system on a Norton twin and what type of switch it would be.
Some will say it is unnecessary with a well fettled electrical system but I think it will be easy enough and worth a try.

Thanks for any input,

Jeff
 
I and most rest the world for a century shy away from oil switch feature but about only place is same spots people fit oil guage taps and can look in lawn mower type supply for tiddy 1/4" thrread switches - which my mower has but may remove as it kills mower on extra steep areas and sometime when hitting a bump that uncovers switch an instant. May have to go through oil system and engine to keep pressure up on idle and hot coasting cruise mode. Easy enough to reverse if your Commando ain't up to it.
 
xbskt said:
Hello to all,

I still need to draw up a diagram but am looking for input on oil pressure sensors on a Commando. I want to put everything except ignition on the load side of a relay that is controlled by an oil pressure switch that closes when it sees running oil pressure.
This will give maximum voltage to the ignition and then when up and running call in the rest of the electric circuits.
The question is where to fit a switch in the pressure side of the oil system on a Norton twin and what type of switch it would be.
Some will say it is unnecessary with a well fettled electrical system but I think it will be easy enough and worth a try.

Thanks for any input,

Jeff
Click to expand...

The Triumph T140 switches would work. If I were doing it, I'd use barb fittings to tee into the rocker spindle crossover hose up top, easily concealing the switch, wiring.
 
THATS a lot of trouble to go to. If you want to run your ignition direct from the battery, just do that through a rely placed up by the coils. If you want an oil pressure warning device, just do that, Fit a Tee adaptor down by the banjo at the back of the timing cover [ there is room, I just checked ] and run power to a light on your headlight from the op switch you have fitted in the TEE
 
concours said:
xbskt said:
I want to put everything except ignition on the load side of a relay that is controlled by an oil pressure switch that closes when it sees running oil pressure.
Click to expand...

The Triumph T140 switches would work.
Click to expand...

Not if he wants a switch that closes when it senses oil pressure, as T140 switches open.
 
L.A.B. said:
concours said:
xbskt said:
I want to put everything except ignition on the load side of a relay that is controlled by an oil pressure switch that closes when it sees running oil pressure.
Click to expand...

The Triumph T140 switches would work.
Click to expand...

Not if he wants a switch that closes when it senses oil pressure, as T140 switches open.
Click to expand...
By using the NC contacts on the relay it will work.
 
OP, it may not accomplish what you want, both of my other vintage kickstart bikes extinguish the low oil pressure warning light at the slightest kicker motion. :idea:

On all my vintage bikes,(moderns won't allow it) I keep the headlight off until engine is running. Always give a four fingers on front of the light before I put it in gear, failsafe redundant check for safety.
 
So the long way around I think I have the pieces of a plan.
Tee adapter fitting at the back of the timing cover plumbed to a T140 switch actuating a relay using normally closed contacts (perhaps use NO for an idiot light) to pull in other circuits.
If the T140 switch is too sensitive perhaps a bit of length on the oil line between the tee and the switch will help add a buffer?
Anyone have the part number for the T140 switch handy?

Thanks for the replies,

Jeff
 
xbskt said:
Anyone have the part number for the T140 switch handy?
Click to expand...


60-3719

Note that the T140 OP switch thread is 1/8" - 27 NPS parallel pipe thread, although there are similar switches for other applications with different threads (NPT, BSP, etc.)
 
xbskt said:
If the T140 switch is too sensitive perhaps a bit of length on the oil line between the tee and the switch will help add a buffer?

Jeff
Click to expand...

The way to buffer the switch is to place a restrictor ( tiny orifice) in-line before the switch. This will delay bleed down. I suspect you will need a very small orifice....perhaps a no. 72 drill size.

Slick
 
concours said:
OP, it may not accomplish what you want, both of my other vintage kickstart bikes extinguish the low oil pressure warning light at the slightest kicker motion. :idea:
Click to expand...

they must have instant oil pressure then or the switch are stuffed.
 
xbskt said:
So the long way around I think I have the pieces of a plan.
Tee adapter fitting at the back of the timing cover plumbed to a T140 switch actuating a relay using normally closed contacts (perhaps use NO for an idiot light) to pull in other circuits.
If the T140 switch is too sensitive perhaps a bit of length on the oil line between the tee and the switch will help add a buffer?
Anyone have the part number for the T140 switch handy?

Thanks for the replies,

Jeff
Click to expand...

Buy a switch designed to do the job.
 
texasSlick said:
xbskt said:
If the T140 switch is too sensitive perhaps a bit of length on the oil line between the tee and the switch will help add a buffer?

Jeff
Click to expand...

The way to buffer the switch is to place a restrictor ( tiny orifice) in-line before the switch. This will delay bleed down. I suspect you will need a very small orifice....perhaps a no. 72 drill size.

Slick
Click to expand...

WTF are you talking about. if you want to know you have oil pressure, why restrict it ???????????????????????????????????????????????
 
kerinorton said:
texasSlick said:
xbskt said:
If the T140 switch is too sensitive perhaps a bit of length on the oil line between the tee and the switch will help add a buffer?

Jeff
Click to expand...

The way to buffer the switch is to place a restrictor ( tiny orifice) in-line before the switch. This will delay bleed down. I suspect you will need a very small orifice....perhaps a no. 72 drill size.

Slick
Click to expand...

WTF are you talking about. if you want to know you have oil pressure, why restrict it
???????????????????????????????????????????????
Click to expand...

The orifice is in the Tee branch line BEFORE THE SWITCH, not in the mainline. The only oil passing thru the orifice goes to the switch. It will get to the switch and pump it up.....ever try keeping oil from not escaping thru a small hole?

Slick
 
kerinorton said:
concours said:
OP, it may not accomplish what you want, both of my other vintage kickstart bikes extinguish the low oil pressure warning light at the slightest kicker motion. :idea:
Click to expand...

they must have instant oil pressure then or the switch are stuffed.
Click to expand...

No, neither. The OEM's had chosen very low pressure threshold switches to avoid nuisance lighting. :idea:

4-5 PSI I believe.

Both are dry sump systems, one uses trochoidal type pumps, the other piston plunger type. Not sure how the Norton with conventional gear pumps would do at kick speeds.
 
kerinorton said:
xbskt said:
So the long way around I think I have the pieces of a plan.
Tee adapter fitting at the back of the timing cover plumbed to a T140 switch actuating a relay using normally closed contacts (perhaps use NO for an idiot light) to pull in other circuits.
If the T140 switch is too sensitive perhaps a bit of length on the oil line between the tee and the switch will help add a buffer?
Anyone have the part number for the T140 switch handy?

Thanks for the replies,

Jeff
Click to expand...

Buy a switch designed to do the job.
Click to expand...

Searching and finding a switch with a higher set point would be easy enough... but having all your lights go out while sitting at a stop may be annoying.
 
Go to a BSA forum and search on oil pressure light. You will find hundreds of posts on the oil pressure light on A65's and A50's coming on while idling on warmed up engines. My 70 Thunderbolt does it all summer. Most people choose to ignore it if it goes out when rpm gets to 1500. I think the general consensus is the light comes on at about 10 psi or less, but running 5 psi at idle won't hurt the engine. I would hate to have the wiring connected to the oil light on the Thunderbolt. Everytime you slowed down the lights would go off, pretty dangerous in traffic. Not sure how this translates to a Commando but I wouldn't be surprised if the Commando may see similar low pressures while idling. Norton and BSA both run a similar style intermeshing gear pump.
The light on my t140 never comes on even when idling in the summer but it has a different style twin plunger pump. Maybe it is more efficient at low rpms? One thing is for sure it doesn't wet sump like the Nortons and BSA.
 
Norton very quickly discontinued the oil pressure guage option in about a season after freaked out owners reporting ZERO pressure shown at hwy speeds yet they lasted as long as usual. So might want to put a gauge on first to see if normal operation in your particular engine stays above switch threshold - if not > keep upping oil grade thickness til it does or not. I've had a couple events of oil filter or hose pumping out oil a switch might of protected engine but I caught the lack of oil before damage by checking at stops and by testing traction before hitting the dangerous twisties to feel like a low air tire alert that turned on over oil tire patch instead. Still encourage the experiment on your time and money the rest of us chance takers can learn from. My prediction is you will be frustrated with shut downs in summer sitting at a stop light or sign or pulling into gas station with everyone getting off on your Commando looks and sounds that dies about the time you pull clutch and release throttle to stop.
 
That's a good question. What oil pressure should the Commando run at. I must admit, I just ride and forget. The bike ought to have an oil pressure warning light at least though. Maybe one day I will organise it. Have to source longer banjo bolts to do this or maybe make them. should be easy enough. I once had to do a quick repair on a float bowl when the banjo bolt stripped the thread on the bow [p the day I was heading out on a long ride before a National rally ]. drilled and fitted a 3/8 UNF helicoil and modified a 3/8 UNF bolt to do the job. still going strong. Dereck
 
A simple way to accomplish your goal, is to use a "latching" circuit on the relay. The pressure switch trips the relay coil, then a NO contact in the relay self energizes the coil (latching it). Once latched, the pressure switch can open, but the coil remains energized. You must have a NO set of contacts on the Ignition or key Sw, and when placed in the coil circuit will break the latch when the Ign. Sw. is turned off.


oil pressure switch in Commando electrical system



The relay. must be rated 15 amps min. but 20 would be better. Divide the wattage of your stator by 12 to get the minimum amps.

Slick
 
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