Oil gauge question

I'm going to install a pressure gauge on my 71 750. Question is what scale 0-60 or 0-100? As I never had one I'm not too sure of the range needed.
Thanks

0-100, the start up pressure can go over the OPRV setting of 50 psi with cold oil and a hole restricting flow until the oil thins.

I have a brand new original Smiths oil pressure gauge 0-100 that a friend gave me way back in the late 70s still in the box, I made a mount for it to sit on the handle bars mounts and have all the lines and connectors for it but still haven't put it on, never really needed it in the 45 years of ownership, but it looks good inbetween the other Smith gauges, as others have said needs to be 100 as when the oil is cold the pressure reading will be very high till the oil gets to temp.

Ashley

MikeG said:

I'm going to install a pressure gauge on my 71 750. Question is what scale 0-60 or 0-100? As I never had one I'm not too sure of the range needed.
Thanks

Click to expand...

Why, to scare yourself? Don't bother.

I fitted an oil pressure light system made by Don Peder. Just so its scares me when it comes on. It never has so I have never been scared.

Dereck

I have the warning light and the gauge. I prefer the 0/80. Don’t let it bother you when the gauge says 0 after a long hot run. They all do that. I like the gauge because I run the oil check valve and it gives me piece of mind.

I pegged a 150psi gauge with 50W oil at under 20f on start up. I noted that, and immediately went to 40W winter oil. I did later change my gauge to full scale 100PSI as most OPV are in the 50-65 range and 150 was a bit over the top.
The real issue is the Over Pressure Valve is they mitigate the over pressure and not really "control" it.
60psi NO
100PSI yes
Been running a pressure gauge for 30 years.

Don’t let it bother you when the gauge says 0 after a long hot run. They all do that.

Mine never has.

I use multi-grade oils. Always have. That's my auto engineering background making that decision. Used to be GTX or Caltex 20;50 now i have been using Penrite 20 :60 , Doesn't smell as nice but what the heck. Its thin enough for cold starts and thick enough to keep the bike going when it's hot.

My oil pressure gauge has twice caught a split conical seal between the pump and timing cover. MKIII is a little different. The anti wet sump valve seats on the seal. I finally figured out that the give away that it's beginning to fail is when the bike starts to wet sump, which it normally doesn't. The seal has begun to split but is still sealing just not on the anti sump valve face. Anyway, when it failed the pressure dropped drastically and I limped home. I would not have known without the gauge. If you have a MKIII that begins to wet sump you might want to check that seal.

Yes, 100 psi. I have a 60 psi and it spends a lot of time pegged. It's what I had on hand when I fitted it and I never got around to changing it. Normal 70-80 degree riding, not flogging, is 50 - 55 psi. I've never seen lower than 40 on a 90+ day on a couple hour 85 mph highway run. Pull off the highway and idle pressure is around 10 - 15. It is nice to know what's normal and easy to spot a change.