As part of a long running saga where the oil pressure light came on from time to time on my 501 New York I ended up first swapping the oil pressure switch twice and then doing a bunch of other things to try and make sense of what was happening and whether my engine was stressed and losing oil pressure somehow.
I've bought a 0 to 100 psi analogue oil pressure switch which has an 1/8 NPT thread (a very very fine thread) and an adapter (M12 x 1.5mm).
I ran the electric start with the kill switch on until I saw pressure readings, then started the bike as normal. The reading from cold at idle speed is around 58 psi. As the engine warmed and as I reved the engine in neutral the reading varied from roughly 50 to 70 psi. On the New York (and Excalibur presumably) the left footrest mount clashes with the oil pressure pipe, so I've got the footrest bracket unbolted and loose during these measurements. This means a road test isn't practical until/unless I adapt the footrest bracket somehow.
I'll add more info to this as and when I have it.
PS: These measurements may apply to any of the air-cooled V twin engines.
Worn crankshaft bearings can cause low oil pressure. Have you had the clutch casing off? The little rubbery (green or black) tube on the end of the crank is also very important...
Mike, thanks for the tip. AFAIK the oil seal should be fine, but it'll be worth investigating again if I find the oil pressure drops when I ride the bike with hot engine oil.
FYI the engine was rebuilt by Benjy and I've ridden it for about 3000 miles post rebuild. He replaced the crankshaft, the mains, the big ends, and the oil pump, as this engine was badly seized when the oil pump failed (this aspect of the story is in ATG 372).
The oil light started coming on after about 500 miles post rebuild when the oil level was low because of a weep from the main engine crankcase breather and old O rings on the dipstick. Since then Benjy, Tom Farrow, and I have been comparing notes and ideas on what might be causing the oil pressure light to come on.
I've just ordered some adapters which may enable me to ride the bike with the oil pressure gauge and with the footrest, etc. refitted. I'll hope to post an update within a week, assuming the adapters arrive by Wednesday/Thursday.
The oil pressure lights tend to come on in single digit PSI, not useful. A gauge is much better. I had to replace my sender, I bought a Lucas replacement.
Glad the crankshaft has been reground, one less thing to worry about. What oil are you using? It has been exceedingly hot recently, maybe the 10/40 is too thin? In the good old days (has there ever been such a thing, or have I got rose-tinted testicles?) I used GTX 20/50 mineral oil. But then, the earlier Morinis did not have an oil pressure light... ah, the ignorance of youth
I have had the oil pressure switch fail a few times on my Sport. The Coguaro seems not to have one, there is a blanking plug where the sender ought to be. In the warning light array there is a light for oil pressure and a charge light. Neither are connected. Me no likey.
John
I've just removed the oil pressure switch just over 2 years after I'd fitted it; as some oil was leaking in the area, possibly from the thin plastic tube that feeds the pressure gauge, so I'm back to using an oil pressure switch at least for the moment. Here's a quick update and summary:
After fitting the gauge I discovered many times when the pressure would drop almost to zero when riding it around, including to one of the MRC rallies in the Peak District. Eventually I rode the bike to Benjy's workshop together with a complete spare LH kokusan casing with starter motor gear, etc. which MikeyMoto had kindly given me a few years earlier.
When Benjy and I stripped down the LH casing on the New York we discovered some additional wear in the internals of the original starter motor bits and pieces including on the casing. The oil pump's gear had also worn on one end of the gear. This was after perhaps 2000 - 3000 km from when the engine had been rebuilt following the catastrophic oil failure predating my ownership.
We surmised that the damage that had occurred owing to the failed aluminium replacements for the flexible rubbery coupling (again predating my ownership) had left some residual damage which had caused the additional wear.
We combined the best parts from the two sets of the LH starter motor pieces, replaced the casing and the oil pump (as I had a spare with me), and serviced the bike. This was winter time 2022/23 so around 20 months ago.
Since then, the oil pressure reading settled down once the gauge had been plumbed in and the bike ridden for a bit. The reading was generally between 38 and 44 psi with it mainly sitting at around 42 psi warm/cold fast/slow short trips (when the oil would be cool) and long trips including riding to and from the MRC track day in 2023 and around the circuit.
I've ridden the bike several more 1000 kms and the oil pressure was consistently good until a couple of days ago when I happened to ride to Kent to meet Benjy for the day. On arrival I noticed oil spots on the ground when I parked up. I checked the oil pressure switch and connector hadn't come loose. I rode home carefully (total journey 244 km) and removed the oil pressure gauge's connector from the LH casing as the tube seems to be weeping slightly.
The replacement switch (which was on the bike previously) initially lit up the oil pressure warning light, but stopped doing so after I'd started and stopped the engine a couple of times. Because the position of the New York's foot rest is directly below the location of the oil pressure tapping it's awkward to replace the switch and impractical to fit a reinforced oil feed tube without more significant modifications.
Overall I much prefer having the oil pressure gauge. Ideally I'd like one that provides an electrical feed to an electrically driven gauge so I don't need a long potentially problematic tube between the engine casing and the handlebar area. I'll probably replace the current oil pressure switch with a new one as I've got quite a few to hand which I bought when the oil pressure light started coming on several years ago.
I promised some photos all those years ago, here they are after I'd removed the gauge. I found it hard to show in a photo how much the LH footrest impinges on the scope to fit the gauge; I have to remove the footrest to run the tube through the gap between the footrest's end and the bracket it fits in. I simply couldn't refit the footrest with the reinforced tube I'd bought to replace this thin black plastic one.
Oil Pressure switch area with footrest.jpg (479.17 KiB) Viewed 1924 times
Removed oil pressure gauge with pipe.jpg (487.97 KiB) Viewed 1924 times
Is there room for an electronic sensor à la Druck, Burkert, etc? You’d need a suitable meter of course.
Edit: I was thinking of something like this, cheap enough for a punt, though the actual connector may be the tightest fit if you have limited room.
Screenshot 2024-09-02 at 08-54-41 Transducteur de capteur de pression en acier inoxydable transmetteur en céramique eau huile carburant gaz air 1_8NPT DC 5V 5-300psi en option - AliExpress.png (180.07 KiB) Viewed 1840 times
Ming wrote: ↑02 Sep 2024 05:05
Is there room for an electronic sensor à la Druck, Burkert, etc? You’d need a suitable meter of course.
Edit: I was thinking of something like this, cheap enough for a punt, though the actual connector may be the tightest fit if you have limited room.
Screenshot 2024-09-02 at 08-54-41 Transducteur de capteur de pression en acier inoxydable transmetteur en céramique eau huile carburant gaz air 1_8NPT DC 5V 5-300psi en option - AliExpress.png
Thank you, from the image I've found similar items in the UK (and China) The New York has so little space that it doesn't look like it'd fit even without the connector, however I'll have a ponder about what might work in the circumstances.
