Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board Mr. Mike's OPRV

Just seen this. I need to go take a look at the cases to see if you can drill out the drain passage. Keeping the new OPRV in place with the body of the old OPRV seems like a reasonable solution and keeps the cases looking standard.

This is an interesting thread, but as a predominantly Triumph guy I hadn't given this much thought before. Triumph twins are by design much less vulnerable to low oil pressure. I do struggle with low oil pressure on my Trident though. In an effort to rule out the OPRV as a possible cause I turned up a thick copper washer to try to seal the nose of the OPRV against the bottom its cavity. Now the cavity and the OPRV nose are both very irregular but I hoped it would at least offer an added restriction to leakage past the threads, which I pasted with a liquid thread sealant. The thing is, the low oil pressure problem persist, so either the cause lies elsewhere, or my effort to seal the OPRV failed.
The mini release valves described are too small for the volume pumped through a triple, but Mark's O-ring solution may be worth a try. I don't believe hysteresis is a factor, especially with hot oil. Tests on a friend's (BSA & triples oil pump) test rig shows that leaks by the piston isn't normally an issue, but the ball valve version always leaks a little.

Should I start a new thread over on the Triples forum?

SR

Just a thought; how about plugging the bleed port and modify the OPRV with several channels like the existing one to bleed off into the dome, which is then vented into the return line or oil tank? I might try that, but not easy to do with the engine in the frame on a Trident. Easier on an A65 I would think.

SR

You can safely blank off the bleed port for testing with oil pressure gauge after the oil is warm, only issue is access for getting the OPRV out. The OPRV is really only needed for cold oil as the high pressure could invert the crank feed seal. In fact I may just think about adding an auto bleed shutoff based on oil temp as an alternative to Mike's OPRV.

The triple's OPRV feed drilling is not tangent to the threads like the A65 so sealing to nose of the OPRV is possible. The depth of the cavity at the thread is 0.620" and the length of the OPRV from the hex flange to the face of the screen mesh is 0.625".
The OPRV that I pulled out has a slight dent in the edge of the screen holder so a fibre washer will probably not seal. If the case were counter bored slightly, a square O-ring could be put in for it to seal against.

Kommando's comment on the seal inversion was for Triumph twins and A65's converted to crank end feed.

My machinist friend may be persuaded to make one rom scratch with a receptacle for a suitable seal. I have a spare set of R3 cases to adapt it to.
I made my copper washer to fit on the Trident cases but found it would fit on the R3 too. I doubt it seals very well against the OPRV nose though, rubber or lead would be better. My kerosene stoves use lead to seal the burners from the tank. Why didn't I think of that before?

SR

Yes, some sort of soft seal is needed so the hex can seal against the case.
Back to the A65, another way to use the Lee relief valve without modifying the case or look too unoriginal is to make another OPRV case in two pieces. The first is the bottom that screws in with sealer on the threads and holds the Lee valve in a recess. A hollow set screw holds the valve in place. The second is just a cap over the hole.

Yes, sorry about the hijack.
Your A65 solution looks sound from here, but I'd be wary of using such a small valve in our climate. Starting an engine below 5C/40F means even a 10w50 is thick.

SR

Yes, that's a great idea. I haven't seen/held the Lee valve yet. Will order a few when the world wakes up.


Cough. Texas. I know. That's a very selfish point of view..

Given that a standard A65 don't have seals that might invert with extra pressure, what's the down side of no (operational) OPRV and running a thin(ish) multi-grade? Clearly, dirty (debris) oil would be bad, but filtered oil?

Steve.

After the dramatic increase in oil pressure I experienced, I switched to 10W30. Even with this lighter oil you have to run at idle until the oil warms a bit. I think you guys are on the right track. I was just trying to have a way for guys without any special tools or access to machining to improve oil pressure. Those miniature Lee pressure relief valves come with different blowoff pressures. I used one that opens at 51 psi and have others that open at 43. Still even with the lower relief pressure (lighter springs) they are pretty small orifices where the ball seats and restrict flow. Warm it up and it works great. The A65/50 is just too nice an old bike to be worrying about low oil pressure.

Cheers,
Mr Mike

[Linked Image]
http://leecat.theleeco.com/ecatalog/relief-valves/en/PRRA1872060L
The relief hole in the threads is only 1/8" so it is fairly small to begin with.

Dave,
You are correct. It is quite small. The valves I used from Lee Company were only .396 " long and .306" in diameter. I got them some years ago. When I visited the Lee website recently, I noticed they have apparently changed the product and are now making but those valves you showed. They should also work. See pic earlier in this thread. I was sorting thru some of my old BSA stuff and found a couple of those miniature OPRV's. If anyone is interested in one of these, send me a self-addressed mailer and with postage and i will mail one back to you. I no longer have a use for them. One of those padded mailers would be perfect.

If you have an earlier A65/50 with the ball type pressure relief, you do not have to make a plug. Just remove the OPRV and tap the cap for 1/8th NPT and you will not have to make the bushing. The whole project is just and easy afternoons work. A dramatic increase in oil pressure without permanently changing anything on the bike.
Mr Mike

Looks like Lee have changed their web site over the holiday break. None of the original links in this thread work anymore.

They have changed their website, but it is back up. Just Google the Lee Company, Westbrook CT. The part number I used is listed earlier in this thread. Talk to a sales engineer and they will fix you up or take advantage of my offer in a previous post.

Mr Mike