Excess Oil in Primary Chain Case - 72 Combat case in 73 750

I have a manual oil supply shutoff valve with ignition cutoff. I am happy with it.

Engine & Transmission :: Engine Upper :: Oil Feed Pipes :: Anti Wet Sump Oil Pipe Tap With Switch - Magneto or Coil Ignition Systems

Anti Wet Sump Oil Pipe Tap With Switch - Magneto or Coil Ignition Systems A solution to a frequent problem of wet sumping. Available in two types - please selection option MAG TYPE: Magneto ignition engines - closed circuit - Tap OFF (to earth the magneto
www.feked.com www.feked.com

I don't forget to open and shut it because my ignition key is on the end of a 12 inch string with a clip. After putting the key in the ignition, I attach the clip through the carb area to the timing cover side of the bike which is a reminder to turn on the manual oil switch. When I shut off the bike, I need to unclip it to take the ignition key with me which is a reminder to shut the oil shutoff switch. Also I have the main fuel shutoff positioned on the right hand side of tank which is a reminder to me to turn the oil shut off on or off.

A few times I have forgotten to turn on the oil switch and I have cranked the engine with my Alton e-starter. I have an electronic ignition with wasted spark. If I then turn on the oil switch and crank, I get an enormous backfire due to wasted spark stroke igniting mixture. So what I have to do is first clear out the fuel before turning on the ignition (oil shutoff). With choke off and oil shutoff closed I open throttle, crank a few seconds which clears out the fuel.
Then ignition and oil switch on and start engine.
Dennis
 
swolh said:
Fast Eddie - You might be right, maybe I misunderstood Matt at CONortonWOrks, but that's not what I thought he said. I just removed the oil pump to be sure that I had not put the gasket between the pump and case on backward, blocking the return orifice. The gasket is correct. (At least I'm not that dumb!!) See photo.

Ahh wait!! .... I re-read the notes from the mechanic who got the bike started a few weeks ago after it had sat for a long time. Before starting the bike he drained 1100 ccs from the sump! So it was leaking oil past the AMR modification during the approximately 2 years that it sat.

When the mechanic got it started he obeserved "Bike returns oil to tank, not as strong as it should, but can't keep bike running long enough to make sure oil system is fully primmed." The next day he ran the bike and observed, " Oil return to tank is better, still a bit anemic." THen after bike sat for 10 days in his shop, he observed, ""attempt to start bike, bike has already wet sumped from sitting (10 days). Drain oil from sump ..., refill oil tank. Start bike, check oil return to tank (returning as it had prior, minor smoking from both pipes)." By "as it had prior," he means "anemic." His final note about future work is to "fix ongoing wet sumping ... and restore oil flow to the tank" which he suspected was due to an oil pump problem. But the oil pump is a MKIII with under 750 miles on it. Unless the AMR modification to the pump has failed, I can't see the pump being the problem, but at this point ... I duno what to Think!?

And maybe the main seal has been leaking for years and the 800 ccs or more of oil I drained out of the primary was building up there for a long time.

So, I'm still thinking that even if the AMR mod has not stopped wet sumping, the ColoradoNortonWorks reed breather valve would be a good addition - and maybe I'll consider also adding a mechanical shut off valve with a built in electronic cut off switch to the supply line to the pump.

Cliffa - The best source for that info is AMR. It was 2017, so I really don't remember, and that means whatever I tell you is not likely to be compeltely accurate or reliable. But here's my feable memory and understanding:. As far as I remember, I think the orignial housing in the MKIII cover for the check valve is rectangular and the stopper for the check vavle is a square block. I think AMR changes the mating surface on the check valve by machining the flat surface that receives the original square block to be curved to receive a ball bearing instead of the square stopper, and machines the housing for the check valve springand stopper to make it a cylinder for the ball bearing stopper, instead of a rectangle. And I recall they also machine the pump itself to add a seal in there. This is what the inside of the timing case looks like now. See photos. That's how the timing case came off: clean as new, so I don't think dirt was holding the bal check vavle open. The dark at the bottom of the small cylinder that houses the check valve is oil, not dirt. I'm sorry if I can't shed any more light on this - and AMR might correct some or all of what I'm explaining!
Click to expand...
Many thanks for taking the time to post the pics. So it looks as though they simply replace the piston plunger with a ball bearing. Would you mind telling me what diameter the bearing is please? And could I ask you one final favour, and post a picture of the oil pump if you still have the case open. I’m interested to see if they retain the MkIII seal, or replace it with an O-ring.

You may want to have a look at this thread, where @robs ss did extensive testing to find the culprit for his bikes incontinence. It’s a long thread, so this link takes you to his input.

W

Post in thread 'Oil valve solution to oil falling to crankcase'

I don't know the answer here.
A couple of years ago I put a Mk3 engine together as a 920.
That started with bare cases so I had to buy the timing cover and fixings.
I bought all of that from Rabers just before they closed shop.
It was all NOS.
A week or two after getting the cases on Ebay I managed to buy the original oil pump and crankshaft for the same cases. They had sold earlier to another buyer, but that fell through.
I didn't do anything to the pump other than fit a new external rubber seal.
The 920 engine can sit for 3 months and barely show any drop in oil tank level. For all...
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