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Jul 18, 2004
I recently received my copy of the INOA Tech Digest and I am very impressed, kudos to those involved!

Given the recent discussion on oil pump servicing, I was surprised that no one mentioned the mod recommended on page 1-25 to avoid wet sumping: a ball bearing & spring inside the timing cover over the oil pump outlet.

Anyone done this mod, seen this mod or have an opinion? It seems like a logical and rather fool proof concept :wink: .

Thanks Dave,

I am a bit fuzzy on the oil pump mod. Is it just a matter of sliding o-rings over the shafts? Are grooves needed.... Is this documented or discussed elsewhere- did I just miss the boat?! :oops:

I need to tear my pump apart (again) to jog my memory!

Notably, '75 MK III Commandos have a check valve in their timing cover. However, as Dynodave points out, there are other leak paths in the oil pump system that must be rectified before you can effectively cure wet sumping.

I tried out the gasket goop in lieu of a paper gasket on the oil pump of my spare engine this past weekend. I used a Permatex product, which was quite expensive. The tube of Permatex Gasket Maker cost only about $4.00 but the surface prep/activater, which comes in a spray can, cost a whopping $12.00!

Thanks Jason,

Any idea on groove dimensions - specifically the depth/shape of the grooves?

I had to laugh when you said the gasket prep was expensive! If only every Norton part were $12.00!! I'd have three running bikes by now! :lol:

Speaking of parts - I did find the lower fork shrouds I was looking for. NOS from Rabers - very reasonable price. Now I can put the front end together!!

I crawled around in my attick looking for my Parker O-ring design manual but came up empty handed. So, I can't tell you the O-ring and groove details/dimensions. Perhaps Dynodave has this information.

I sure like your photograph of oil pump components; it looks like it came out of a magazine!

Personally, I don't find wet sumping to be a major problem; perhaps I've been lucky. As such, I would not go to the trouble of modifying my pump to accept O-ring seals. I do, however, believe in the O-ring concept.

Why don't you run the bike without the oil pump mods. Then if you find wet sumping to be a problem you can always modify it at that time.

Thanks for taking the time to look for the o-ring info.

It seemed like a simple mod so why not try it while I've got the bike apart, but you are right - maybe I will leave the pump alone and see how things are - I am itching to have the bike running as it has been 4 years of slow rebuilding... and I have yet to ride an inch or hear it run... :( I keep falling prey to 'while I have it apart' syndrome.

I would still be interested in the information if not for this year but for next winters (Bottom end) tear down.

The photo was a quick shot on my desk with a webcam! . I used PhotoShop to clean it up and colour correct it (blue cast from my monitors). There are more photos of parts on my site, as I go over each part I try to document the process or at least the results.

You mean the shutoff valve? That would certainly stop the wetsumping! People have done that on Nortons too. But the first time you ride away and forget to turn it on... :shock:

... and its happened more than once, I can assure you. A ball valve is just too darn easy to forget about - until its too late!

However, this bike looks like a racer. So the owner probably has a check list to review before cranking it up. I'm sure that turning on the oil tank ball valve is step number one on that list.

Saw it happen this way. Man rides into a large motorcycle meet and is distracted by the tight spaces and eye candy. So when he shuts off the bike he forgets to turn it off. Now when he leaves he remembers to turn it on . But he has now tuned it off. He made it six miles. norbsa

I admit my bike has this thing that the oil leaks into the cases...but is this really a problem?
Mine has done this for thirty years and being lucky and having a 72, the oil just gets pumped up into the tank when you start it, which can be stupid, I admit, if you have filled the oil tank up when the machine was cold(young and stupid), and the overload of oil overflows out of the tank and down in front of your rear wheel......but that only happens once...I know about it. Or if you have one of those older setups that had the tube running out of the side of the motor case and running back towards the rear tire......
Only time recently my wet sumping got strange was when the seal between the case and the primary case went bad a couple of years ago, and the oil that sat in the sump, drained into the primary case and the clutch had more than a good bit of lubrication. Strange to find a couple of quarts of 20-50 in the chain case...made it darn hard to kick over too.
I've always just started it up and let the motor run slow until I hear the telltale farting sound of the last of the oil coming out of the breather pipe into the oil tank...then I can put on my leathers and go for a ride. Maybe I've been lucky, everybody seems to be thinking it's a problem, but other than maybe causing some pressure in the cases from the pistons pumping out the oil...can't see what the worry is...something must be right about having all that good oil on the bearings for weeks at a shot.....with over 130,000 miles....(Knock on wood)...I've never had the cases apart since new....only did new rings and a deglaze twice I think and it still has the original pistons too. Been lucky maybe, or a good airfilter(wet foam like the motorcrossers use) and changing the oil at least once a year has done the trick...don't know. Maybe because I warm it up for the time it takes to put leathers and such on....
So.....if anyone can explain to me any other reason, besides the fact that it makes the stinker hard to start in the winter, that I should install one of these valve things....please enlighten me. Maybe I've indeed been ever so lucky........Never too old to learn...Ride safe! Piperboy

Hi ~ I have to say if you have put in all these miles on your machine ~ it would seem a classic case of ~ "If it works for you~ !"

I went down this road with dynodave, it seems a LONG time back.. with the wet sumping thing..

I for one, am one of those that has become "gun Shy" about the concept of a anti- leak valve.

I had one on my Commando and while I found one has to be EXTREMELY careful when first fitting it ~ that is; ensure the engine side to the oil pump is primed before starting up ~ I never had any problems with the thing.

BUT~ maybe it was the rumour or fact created by the crew at The norvil Shop or someone . ie: we should NEVER fit anti leak valves because if they fail it WILL result in total tradegy !

With this thought in mind .. I removed it.

I am a tad dubious about fitting the same concept, Ball and spring to the casing as this would seem to be the same thing..

As for the tap thing.. I agree .. to ~ potentially far too disasterous !

I recall when I was involved in the auto electrical trade, there was a vehicle .. which I cannot recall ~( maybe it was a Bulldozer (??) , aVolvo loader or a stationary engine setup.)

It had an illuminated push button switch, and when the ignition came on, the thing would 'pop' out sounding and an larm.. or buzzer.

Untill the operator executed the required routine, 'he' did not push the button in ~ which of course stopped the thing flashing and buzzing.

As it is not a high priority I have never gotten around to finding .. creating this fitting.
It would work great with the tap arrangement.. or simiarly wired in seqence with a micro switch would also work.

Of course this is all academic if one was to just pull the whole bloody thing apart and modify the pump in accordance with "Dave's" mud map!!
Good idea about a "Failsafe" switch...but doubt many would put one in....we are in general not too pleased to be buzzed and beeped would quickly get on most rider's nerves.
The only buzzer thing on mine is the one on my directional lights...I wear a fullface helmet and even with 30 years of riding this thing...I can't see the signal lamps without bending my head, and I forget to turn off the blinkers....and here in an intersection...these bozos in the cars will see a blinker and even if you are doing 60 mph...they will assume you will be turning and wait till you are ten meters from the corner and still doing 60 and pull out in front of you. The driving teachers teach them to pull out if the oncoming vehicle has signalled it wants to turn, something my father went ballistic about, teaching me to wait until the oncoming car had really MADE THE TURN...and to ignore the blinker lights because people forget to turn them off. Back then, there were no automatic turn off things on blinker lights. But here...they are very well brain washed into thinking that all drivers know what they are doing and can't make a mistake, so they will pull out. After did signal that you wanted to turn........ They could write that quote on the tombstones of a thousand bikers here and every year I see hundreds more , that are just tooling along and thier blinker is blinking along too. So...for myself, after three or four close load and nasty machine has a loader and nastyier buzzer that makes me turn my blinker off.

Getting back to my original question...what reason is there to stop this oil from flowing into the there some danger, does it do damage...or iis it just a case of making it hard to start in cold weather???? That:s what I would dearly like to know. At one point, I mentioned to Les Emery that I just started the bike up and waited for the oil to get forced back into the oil tank before giving any throttle...and I seem to remember getting a comment sort of like yours...that if it had been going good for so many years....that there must be something right about it. But I still would like to know what reasons people seem to have that would recommend more than a rebuild of the oil pump...which to my experience didn't change the amount of oil going into the sump much anyway. I did though once find that using Mobil1 made a heck of a lot MORE oil go FASTER into the sump...too thin a viscosity I think....and I stopped using it and went back to castrol 20-50W.
Thanks once again for all input!! Ride safe!

I think one of the dangers of wet-sumping is the reducion in volume inside the crankcase. So when you start the bike, there is a potential to "pump out" a crank case seal, owing to this reduced volume.

However, having said that, all my British bikes have had a wet-sump problem to some degree. And I've had no problems with "blown" seals in some thirty years of owning them.


Suppose that is exactly what happened when I used that Mobil1 oil...ending up with 2 quarts of oil in the primary chaincase....seal was a bummer to get out...but I got it changed and switched back to Castrol and the problem hasn't reappeared....but point taken about blowing principle...any seal in the system "Could" blow....all the way up to the rocker arm covers and at the bottom of the barrels, the whole area is open and free to the sump area and the pressure must indeed be a bit strong for all the seals, but I have never had any really nasty side effects from the exrta oil in the sump and even rebuilding the oil pump didn't stop the oil from returning into the goes on and I just don't worry so much about it....

But...I will admit that I have gotten "Winded" every time I have to start the bugger in the fun at all, and not even always successfull, if I'm honest.....maybe in my next life I will weigh more and can kick it over better...or just get it fixed....HUmmmm...thats an idea!
Best and safe riding! piperboy
Piper boy

I have niether experienced it or know of such an ocurrence but Ibelieve the first thing that may well happen is that the seal between the crankcase and the primary drive can blow and of course the engine oil would flow into teh primary drive.

I am / have been always one for starting up and idling up to bring the oil back to the standard levels. Additionally , warming up the oil before delivering any "styck" to the engine / throttle.

My Trident was the easiest to repair the wet sumping.. but required the engine to be removed.. ALthough I did explain my method on and one of the blokes in the USA emailed me thanking me personally for the idea.. and he did not remove the engine..and achieved the same result..

But again this is academic as we are discussing Commandos here !
Don't know much about the triples...had a workmate in 79 or so that used to have a Trident...but other than personal experience with one.
The story with blowing the seal into the primary case is more than likely the main problem you would get from the oil being too full in the sump, as you say, but other than that...don't know...any other ideas, or should we leave this as the main problem.....and one we can live with?
Think so...unless one of you has another earthshaking reason to do something about it, I will leave it as is...but then there is a simple question...what, other than putting in one of these questionable valve things, can one do to stop this oil getting into the sump? Does this spell a new oil pump, or is there another solution or thing that should be fixed...or did these things do the wet sumping thing, back when they were new and the folks at Norton just didn't worry about it either?
Can't remember, just seems the problem was always there...sort of like a's there, but you don't think about it unless you have to sneeze.....
Best and greetings to the world down under.....
piperboy states " principle...any seal in the system "Could" blow....all the way up to the rocker arm covers"

PO installed a vent fitting on one of the rocker covers on my 74. Looks like a grease zirk but is open to the atmosphere. I didn't know what it was for and have had an expert opinion that "it was done in the old days to collect overflowed oil but was unnecessary". According to what piperboy is saying, could this have been (or is) a solution to pressure build-up in the oil system due to the sumped oil? IOW does anyone think that this might be the solution that keeps seals from blowing?
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