Wet Sumping, Oil Pressure Relief Valve and AMR Modification

I recently had my timing cover modified by AMR in Tucson. Basically the modification is the addition of a ball valve and spring that pushes up against the outlet of the oil pump. The timing cover is bored to accept the spring and ball valve. Also there is a special seal (1/8 inch thick O-ring) that goes on the end of the oil pump.

The other day I installed the modified timing cover along with oil lines but I left the rocker feed pipe off. The next day I had a nice puddle of oil under my motorcycle and determined that the leak was coming from the rocker feed port. Thinking that this may have been residual oil, I left the rocker feed pipe off for a few more days and the puddle under my bike got rather large. So of course I figured the AMR modification didn't work. I removed the timing cover and checked the ball valve and everything looked fine. So I reassembled the timing cover but this time I removed the oil pressure relief valve and then plugged off the port that directs oil back to the inlet side of the oil pump. This morning I checked my bike and there wasn't a drop of oil coming out of the rocker feed port. So apparently the AMR ball valve modification seems to work and it's doing its job.

But what to do with my oil pressure relief valve. From looking at the valve assembly I can see that oil could pass through the three holes and then along the sides of the piston. Also I can see that oil could leak past the three threads at the end of the valve body assembly. What I am wondering is if anyone has ever addressed this problem and had any good results?

Re: Wet Sumping and the Oil Pressure Relief Valve

Norton did with the MK3 850.
They plugged the hole which returns the oil to the inlet side of the pump and drilled a new hole in the timing cover so the blowoff oil is released into the timing chest.
Early engines were also built this way. Jim

Re: Wet Sumping and the Oil Pressure Relief Valve

On my oil pump/OP valve test machine. When running at pressure, you would be shocked to see the amount of thread leakage flow before the OP valve actually starts to open. The flow gauges show the story :!:

Re: Wet Sumping and the Oil Pressure Relief Valve

dynodave said:

On my oil pump/OP valve test machine. When running at pressure, you would be shocked to see the amount of thread leakage flow before the OP valve actually starts to open. The flow gauges show the story :!:

Click to expand...

That is very true.

Installing a socket head setscrew in the timing side engine case with some blue locktie -1/4 -20 the hole is already tapped, and then drilling a new hole into the passage so the relief oil vents into the timing chest will cut the wetsumping speed by a large amount. Jim

Re: Wet Sumping and the Oil Pressure Relief Valve

Thanks for the replies. I wasn't aware of the Mark III being plumbed that way. As for the pressure relief valve I think it is the luck of the draw that the threads would actually seal well. Mine sure don't.

So here are two different options I am considering. I will go ahead and plug the threaded hole in the crankcase with an allen set screw as shown in the picture below. As for the timing cover I could drill a hole so that the relief oil can drain into the crankcase. I believe that there will be plenty of clearance around the oil pump so the oil can flow freely. Or another option I am considering is to simply notch the timing cover at the gasket surface. I would drill the timing cover in the same fashion as I have seen on the Mark III timing cover. However, I believe that I would have great difficulty locating the hole properly.

Location to drill new pressure relief valve drain hole



Plugging the Relief Valve Port with 1/4-20 Set Screw

Re: Wet Sumping and the Oil Pressure Relief Valve

Just cut the gasket away and the oil when cold will spray on the back of the oil pump. Once the oil is warm/95% of the time the OPV does not flow any oil.

Re: Wet Sumping and the Oil Pressure Relief Valve

This afternoon I modified my timing cover by drilling a hole so that the oil from the oil pressure relief valve will drain back into the crankcase. Also I plugged the existing hole in the crankcase where the oil pressure relief valve drain used to go. I ended up using 2 set screws. One was tightened on top of the other along with Loctite.



Hole drilled for pressure relief valve drain



Hole plugged using 2 set screws



I still have yet to finish one of my other projects by installing the top end back on my bike. Time will tell how well this modification works. I would like to thank everyone for your input.
Peter Joe

Re: Wet Sumping and the Oil Pressure Relief Valve

dynodave said:

Just cut the gasket away and the oil when cold will spray on the back of the oil pump. Once the oil is warm/95% of the time the OPV does not flow any oil.

Click to expand...

I may be talking rubbish here but I seem to recall that when the timing cover is off you have to screw something into that threaded hole or the oil from the tank just runs out. I presume you mean cut the gasket after you've permanently sealed that hole?

Ian

Re: Wet Sumping, Oil Pressure Relief Valve and AMR modificat

I thought I would give and update on my timing cover modification.

Initially when I put my modified timing cover on the bike I waited about 6 days before removing the timing cover to see how much the oil pump leaked. About a tablespoon of oil drained out at that time which didn't seem too bad but I thought I could make it better. I had also removed the oil pickup screen during that period of time and observed no oil back draining through the scavange pump passageway. That meant that the AMR oil pump modification was working.

So I dismantled the oil pump to see what AMR's modification looked like. The modification consists of boring the pump body to accept two O-rings. I also noticed that they did not resurface the end plates of the oil pump. The surface finish on the end plates from the factory, especially the brass one is pretty rough. So I resurfaced the pump body and the end plates with a final sanding using 600 grit wet and dry paper. When sanding with 600 grit you are getting in the realm of polishing and you can easily see any surface imperfections that you may need to work out. When I reinstalled the oil pump I mounted it with a temporary bracket to hold the spring and ball valve in place. I then let it sit for several hours to see how much the pump would leak. Amazingly the only oil that came out of the pump was from the oil pump drive shaft and that was just pre-oiling oil which eventually stopped.

There was some real light oozing of oil around the ball valve. So I took a hammer and drift and tapped the ball into the seat. Amazingly that stopped all oil from leaking around the ball valve. You don't want to hit the seat very hard because the end wants to flare out. Here are a couple of pictures:

AMR modified oil pump body with counter bored shaft holes and the O-Rings.


Leak Checking Oil Pump with temporary bracket to support the ball valve and spring. Photographed after 5 hours of sitting.


On the initial run up I had temporarily mounted an oil pressure gauge by fabricating a special banjo bolt adapter. Oil pressure was regulating just fine but seemed to be regulating just a little bit too low. So I fabricated a shim for the oil pressure relief valve and that brought the pressure up to 55 psi when cold. Once the oil got warm the oil pressure dropped to 45 psi at 4000 rpm. So everything checked A-OK.

The bike has now been sitting for 9 days since this modification and the oil level has not dropped at all in the oil tank. I am happy! It actually turned out better than I thought it would. I reinstalled an oil pressure gauge and as soon as the engine started the gauge started reading pressure right away. So it doesn't take very long for the oil galleys to fill with oil.

One final note - even though I am happy with the way I modified the timing cover, if I were to do it again for me or someone else I would take the time to make a drilling jig so that I could accurately drill the oil pressure relief valve's outlet much like the 850 Mark III's. Then I would plug the original oil pressure relief valve's outlet using a pin with sealant driven into the original passageway. The reason is because the modified timing cover can then go from engine to engine without the need to plug the threaded passageway in the engine case. This makes it more Murphy proof.

Peter Joe

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

Hi All.
I red all the thread and i have a doubt.
If i want to mount the MKIII timing with oil non return valve on my 750 engine i should before reworking the crankcase plugged some oil passage?
Or can i mount without reworking.
Thanks for help.
Ciao
Piero

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

pierodn said:

I red all the thread and i have a doubt.
If i want to mount the MKIII timing with oil non return valve on my 750 engine i should before reworking the crankcase plugged some oil passage?
Or can i mount without reworking.

Click to expand...

It isn't absolutely necessary to block the crankcase oil passage, so yes, you can just fit the MkIII timing cover if you wish-as the standard MkIII timing side crankcase has the passage-but it isn't plugged, however, the gallery is already threaded so it's a reasonably simple job to make a plug from a cut down timing cover screw with a screwdriver slot cut in the end.

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

Dear Les,
the hole i should plug to use the MKIII timing with non retiurn oil valve is that indicated by the arrow in the crankcase picture posted by Peter Joe?
No new holes in the MK III timing cover i have to do.
Thank you
Piero

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

pierodn said:

the hole i should plug to use the MKIII timing with non retiurn oil valve is that indicated by the arrow in the crankcase picture posted by Peter Joe?

Click to expand...

Yes.

pierodn said:

No new holes in the MK III timing cover i have to do.

Click to expand...

Nothing else needs to be done.

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

I have the MKIII cover on my 72. No holes drilled, no holes plugged.

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

Perhaps we need a separate Forum for 72s with a MK3 timing cover. :lol:

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

worntorn said:

Perhaps we need a separate Forum for 72s with a MK3 timing cover. :lol:

Click to expand...

Yes, of course we do. And who could question your wisdom and insite, but alas, I am sure your great idea won't go far. :cry:

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

Hi.
Please, to my knowledge, what is the difference in having the oil passage hole closed or open?.
Thank you.
Piero

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

pierodn said:

Please, to my knowledge, what is the difference in having the oil passage hole closed or open?.

Click to expand...

Once a MkIII timing cover has been fitted then there's no difference because the oil gallery becomes redundant.

PeterJoe plugged the oil gallery because he has modified a pre-MkIII timing cover.

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

Hi and thank you.
Well, i have not to plug any hole.
Ciao
Piero

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

To jump on this bandwagon I've got a 72 with a MkIII timing cover and it still wet sumps. Maybe a worn pump?