My 1971 Lightning has a 1967 engine. The electrics have been butchered over the years by previous owners and there is evidence of several melted wires, especially the reds to the frame. So I am replacing the main loom.
In preparation for that I have been thinking about how to adapt the loom for the combined rectifier and Zener diode and the oil pressure switch being in a different location. Trouble is, although the 1971 engines switch seems to be easy to see, on my older engine, I can't find it at all. Where should I be looking? Could it have been blanked off?
I'll have to double check on my 1970 engine but I believe the oil pressure switch is screwed in under the engine just in front of the oil pressure release valve. Unfortunately, the pre-1970 engines did not have the tapped hole in which to plug in the oil pressure switch as far as I can see from the parts books?
Just double checked with a 1969 User Manual and there is no mention of an oil warning light and therefore assume pre-1970 one was not built into the design of the bike or the wiring diagram.
The oil pressure light switch first fitted to the A65 for the 1969 season models.
Thank you both so much for your help with this. There is no such shape in the casting at that point on my engine so I guess I am in the not-so-sweet-spot of having a date of engine that has the weak timing side bearing and a less than ideal oil pump, with no way of monitoring oil pressure. I can't see how a conversion would be possible either. I will have to be careful.
Hi Richard,
How desperate are you to have an oil pressure switch? Although there is no casting to make a drilling, it is possible to drill in through the cases to fit a switch or gauge. If you remove the oil pressure relief valve you will be able to see how far in it goes and then measure the location for drilling on the outside making sure that the hole will not interfere with the OPR valve. This can be done without stripping the engine as any bits of aluminium can be easily retrieved especially if the OPR valve hole is stuffed with a clan rag before drilling.
If you do this, only fit the pressure switch as this is set at a very low 7psi. If you fit a gauge you will never be able to stop watching it.
I have a switch on one A65 and periodically look at it on very hot days when at tick over. So long as the light is NOT on then all is well. My other one has pressure gauge and it is quite amazing how the oil pressure varies during the course of a ride depending on temperature and engine speed.
Dave.
Hi,
If you do manage to fit a gauge, a 20/40 oil, at normal operating temperature, running between 3000-4000rpm, you should get 40-45psi.
Best wishes...
This might sound daft but I sometimes wonder what use an oil pressure warning light is. The oil pressure switch on the OIF BSA's is set at 5-7psi. So when it goes out the pressure is somewhere above 7 psi. If, as I did, inadvertently fit a higher pressure switch then when hot, the light would come on at tickover. That had the effect of making me paranoid - for a while.
Looking at it logically if the oil is circulating (visible from the return at the top of the tank) then lubricant will reach the necessary metal bits as deemed by BSA. Is it desperate that it is at a high pressure? Certainly, the faster and harder the engine is working the more lubricant will be needed but this is mitigated by the faster the engine runs the more is being delivered!
Are we maybe a bit oversensitive to Oil Pressure?
The normal reason for the warning light is just that - to warn of what could be a catastrophic loss of oil pressure. Obviously if it occurs at tick over it is a matter of seconds to check inside the oil tank, I think riders like the reassurance that the oil is circulating as it should at higher revs out on the road! If the light illuminates at high speed (relative) stopping the engine immediately could avert a disaster - whether or not the light function would be noticed at speed is another matter!
Hi,
I check the oil pressure on engines with shell bearings, a quick google came up with this:
https://meridianautocare.com/top-5-causes-of-low-oil-pressure-in-your-engine/
Best wishes...
Hi,
'Ignorance is bliss' as the old saying goes. As far as I know it was not until the A65 and not even the early ones, that BSA thought that a low oil pressure light was needed. Perhaps the reputation of engines blowing up was part of it but how many miles were covered on A10s and A7s by riders blissfully riding for mile after mile in the knowledge that they had checked the oil level and the return in the tank, totally ignorant of what the oil pressure was.
Back in the day when we all thought we needed things like oil coolers and oil pressure gauges I fitted one to an A10.
I knew my OPRV must have been faulty as the oil pressure went up to about 100 psi but even allowing for inaccuracies I had oil pressure that would be more than enough for my A10.
However, as I went along on my journey the oil pressure came down as the temperature of the engine went up to the point that there was almost no oil pressure. Logic said the engine was about to blow but experience said that it was not as it had been running perfectly well before fitting the OPG and did for many miles after I took it off. Around that time Triumph published an article about a 650 twin that was run for the equivalent of, I think, 10.000 miles with no oil pressure and when stripped and examined had no more wear than would be normally expected. Obviously the flow was there so the oil was circulating and doing its job.
I find the oil light useful on my A65 especially after it has been standing for a while. Before starting the engine I will slowly kick the engine over until the light goes off (usually 3 or 4 kicks). At least I then know that there is oil in the crank and at the big ends ready for starting. The other use is noting how long the light stays off for. With a cold engine the light stays off for quite a few seconds indicating to me that there is some resistance to the flow of oil and that the big ends and bush, if you have one, are in reasonable condition. If the light does not go off when kicking over or goes off instantly you stop kicking then a wear problem probably exists in the bottom end.
Waiting whilst stationary at tick over it may be worth glance to see if it is still off especially when it very hot both engine and weather wise. So it serves as tea stop indicator as well.
But unless you fit one to your A7,A10 etc. then 'ignorance' can still be bliss.
Dave.
I can verify that these engines will run without oil pressure. Instead of keeping my 1962 A50 as a retirement project I got impatient and handed it to a local restorer of classic bikes to get the job done. When I got the bike back it was very pretty, but I had to attend to a few mechanical issues early on. At the 250 mile engine oil change I removed the pressure relief valve to help prime the pump. I don't know why I dismantled the valve, but when I did I found that it had been assembled in reverse order. This being, valve seat, spring, ball and cap!!! It took a few moments to believe what I was seeing. I struggled to believe that the engine had run for 250 miles without oil pressure. There had been no noticeable additional mechanical noise.
He accepted liability and on stripping the engine down to check it over he did find that there was wear on the big ends and the timing side bush.
Hi,
I think that with the OPRV being in back to front that not only would there be no oil pressure but a lot of the oil would not even go through the bush and big ends as the hole were the OPRV should be would be the line of least resistance. I think luck was on your side to get 250 miles. Just a thought, but if the warning light had been fitted to your early model you would probably have noticed!!
Dave.
Thank you so much for all these really useful replies. I am not sure that I am brave enough yet to drill into the area of the pressure control valve but may have a go next winter. I had no idea that was an option. Meanwhile, without setting another hare running, I was thinking of putting oil warning light to use as an ignition warning light. I am assuming that as the oil pressure light has a white lead to it from the battery, if I connect the brown and white one into either of the wires coming from the alternator then that would be job done. Maybe it could affect the regulator though? I have one of those combined ones that does away with the zener diode.
Hi,
There is a reg/rec that has a charge light facility but what about one of these?
I have one on each A65 and one on my wife's '51 Flash. This one is from Paul Goff but others are available.
Dave.
Without a bit of clever electronics, it is not possible to wire in a charge indicator light on this bike - you definitely don't want to connect a 12V bulb directly across the alternator. Besides, it is not normally a failure of the alternator that you need to worry about but a failure of the rectifier/regulator to convert this into 14.5V going into the battery. As said, if you haven't got an ammeter fitted, the next best thing is to fit a battery voltage monitor. Even on my modern Tiger 800, I have one plugged in to the front accessory socket so I can keep an eye on the battery voltage as I ride along to make sure it is charging at 14.5V.
Thanks Dave, great idea! Much more useful than standard.