XS650 Top End Oil Pressure Gauge

I've been wanting to monitor the top end oiling of my XS1B for a long time. So, I added an oil pressure gauge to monitor the oil pressures delivered through the front oil pipe to the top end.



Back in 1974, I had plumbed an oil pressure gauge to the main oil gallery, front of the right side clutch cover, on my other XS1B. Almost had a heart attack when I saw the low pressures, 15-20 psi cold, almost nothing when hot.

This time around I thought I'd do it differently and NOT molest any precious, rare original castings. So, I added a fitting to the top of the oil tube, out-of-sight under the fuel tank.

For reference, here are some threads that cover oils and mods for oil cooling and pressure gauges:

http://650rider.com/index.php?name=Forums&file=viewtopic&t=6055
http://650rider.com/index.php?file=viewtopic&name=Forums&t=6253
http://650rider.com/index.php?name=Forums&file=viewtopic&t=7958
http://650rider.com/index.php?name=Forums&file=viewtopic&t=8678
http://xs650temp.proboards.com/thread/15070/oil-cooler-revisited?page=1
http://www.xs650.com/forum/showthread.php?t=3468
http://www.xs650.com/forum/showthread.php?t=8153
http://www.xs650.com/forum/showthread.php?t=8572
http://www.xs650.com/forum/showthread.php?t=10572
http://www.xs650.com/forum/showpost.php?p=365933&postcount=29
http://www.thechopperunderground.com/forum/index.php?showtopic=54246#

 

Modifying the front oil pipe for an oil pressure tap:

With the front oil pipe removed, file a flat on the very top, removing the pointed top.
Mark and centerpunch the center of this filed flatspot.



Drill straight and square with a 5mm drillbit.
Carefully tap the hole to M6 x 1.0.



File off the top again, straight and square, leaving a small flat annular ring around the threads.
There's enough copper in there for about 2-1/2 threads, 2.5mm (0.100").

 

Making and fitting the 1/8" compression fitting adapter:

We'll modify a 1/8" compression union, as shown on the left.
On the right is the modified union, with M6 x 1.0 threads.



The union is chucked-up in the lathe, and one end is turned down to 6mm OD.
Then a threading die is used to cut the M6 x 1.0 threads.



This newly threaded end is parted-off, leaving about 2-1/2 threads, 2.5mm (0.100").



The oil pipe threads and the modified union threads are thoroughly cleaned, then assembled with red Loctite.
The fit needs to be snug, but not so much as to strip the brass and copper threads.

 

Finishing the front oil tube modification:

After the Loctite cures, the front oil tube is ready for the 1/8" tubing



Attach the 1/8" tubing to the compression fitting.
Do not torque through the loctited threads. Apply torque to only the brass fitting's hex heads.



Reinstall the front oil tube to the engine.
Route the 1/8" tubing up, around, through the frame, to the desired location.

 

Modifying the 0-15 psi oil pressure gauge:

Fitting the standard 1/8" NPT to 1/8" compression adapter to the back of the oil pressure gauge takes up to 1-1/2" of length.



I wanted to shorten this, so modified the brass adapter to be a 1/8" compression fitting with 1/8" NPT threads.
This reduced the installed length to 0.9".



The wiring emerging from the back of the gauge is for the internal lighting.
A white high-brightness LED is bonded inside the gauge shell.
A 390 ohm resistor is soldered in-line to the power wire, and all sheathed with heat shrink tubing.



A bracked is fashioned from 0.062" aluminum, to be clamped by the bottom handlebar clamp bolt, between the clamp and riser.
Soft/compliant foam is bonded to the bracket, with cutouts to clear the gauge's backside screws. The cutouts for the screws will keep the gauge from rotating in the bracket. The modified 1/8" compression fitting also clamps the gauge to the mounting bracket.

 

This video shows the cold and hot oil pressures I'm getting on my XS1B:

 

Absolute coolness! Well done , DogBunny!
Zero psi when hot??? Let the neurosis begin.

Hey, Robinc. This "new ground" is seriously worth debating. By revealing top end oil pressures, are we introducing a viable diagnostic tool, or opening a can of worms? I've seen several burnt-out top-ends on this forum, likely attributable to lubrication failure, and long wondered if top-end oil pressure monitoring could be useful. We really don't have much data on the relationship between oil delivery rates and engine life expectancy, aside from the usual "little to no pressure" reports from main gallery pressure taps, and the 'splattering oil' test from an open valvecover.

I have this sequence of 'top-end oil delivery' scenarios in my head:
1- If there's any top end oil pressure, there's more at the main gallery.
2- If just a little bit of oil reaches the top-end, perhaps misting from camchain fling-off, is that enuff to keep the top-end alive?
3- It takes at least 1/3 psi at the mains just to push oil up the front oil pipe.
3- If just a marginal 1/2 psi is at the top-end, that's probably enuff to keep it from burning up.
4- I've experienced top-end clatter when top-end hot pressures get below about 2psi.
5- The majority of top-end oil is squirted out small nozzles in the rockers, aimed at the pad/cam interface.
6- XSJohn (rip) installed some auxiliary oil squirters in his intake valve covers, aimed at the valve tops, and reported reduced clattering.
7- After installing a high-volume pump, my pressures went up about 30%, and got reduced clattering.
8- What I'm also interested in is more flow to the top-end to enhance top-end cooling.
9- Outside of conjecture, it would take additional thermal monitoring instrumentation to validate all that hypotheticalness.
10- It kinda makes sense...

 

Hey, DB, yeah, I probably need to clarify that. Pushing fluids uphill requires pressure at the bottom. Taking pressure readings at various heights on a tall column of fluid will reveal reduced pressures the higher you go. Atmospheric pressure (14.7 psi) at the base of a column of water will push that water up about 32 feet. Oil, being less dense (at about 75%), will be pushed up to about 43 feet. That works out to about 35" of head per 1 psi, or about 18" per 1/2 psi, which is about the height difference between the oil pump and handlebar mounted gauge.

So, if the handlebar mounted gauge shows 1psi, the mains are at least 1-1/2psi, and the top-end around 1-1/4 psi. If the gauge shows ZERO psi, who knows what it is down below. Since there *was* a reading while the engine and oil were cold, we know then that the pump is indeed working. What's left is to figure out if this is something to worry about, or just take a pill and go back to bed...