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ET: Engine (Twin) Wet sumping

andrew peters

Active Website User
VOC Member
When I bought my Rapide I had all sorts of ideas (not all my own ideas I should add) about solving all those problems and the many horror stories I had heard about... and many of the solutions, I'm glad to say. I found were not applicable to my bike.. I bought from Conways their anti sumping valve, a beautifully made and (probably) easy to fit part. However, I decided it was not the prettiest thing to hang off the side of the engine (although it could possibly distract, only slightly, from the hideously ugly, in my opinion, Elephants Trunk breather! I figured Any breather must be better than that, sorry) So, I have no anti sump valve (except in my spare parts drawer) and haven't found a need for one, I'm changing the oil regularly (20-50) and using the bike as often as possible, even in winter, which is quite mild on Tropical Vancouver Island. I should add my 48 Indian Chief has a oil line tap, it's a gas pipe fitting.. The Indian gets little use, mainly because it's not that much fun to ride. I also have a 1991 Harley that cheerfully dumps 3 quarts of oil out of the breather pipe on start up every spring, the 72 Shovel and even the 54 Panhead are much better behaved. The 75 BMW R90S of course is Teutonically faultless
 

Peter Holmes

Well Known and Active Website User
VOC Member
Yes, monograde should help, but then you have to wait a while for the oil to warm up from startup till wanting higher revs. Another plus of monograde is it sticks to components longer when not using the bike like in wintertimes. Basically it might be good to have only mnimal oil level in the oil tank for faster warmup at each start. My guess the typical Vincent runs a bit cold most of the time regarding oil temperature ?

Vic
Tony Maughan rebuilt my engine many years ago, and he did a fine job, but it did not eradicate the wet sumping problem, close engineering tolerances will slow it down a bit, certainly to an acceptable level, for me anyway, but does Vic have an engineering solution whereby the oil stays in the oil tank when the bike is not in use, as a previous post stated, the real problem here is gravity.

As someone else previously mentioned, I also have anti sumping device, brand new, never fitted, I just cannot bring myself to install it, what does it do, suck or push a spring loaded ball off a seat to allow the main pump oil feed to pass, fully bled with no air locks, no thanks, it would terrify me.

Good oil is relatively cheap (when compared to a tank of premium fuel) easier and safer to just unscrew your magnetic drain plug, check for contamination, refit and fill up, use your bike regularly, aim for 8 months of the year, happy days!
 
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oexing

Well Known and Active Website User
VOC Member
Actually I cannot post any experience with the Vincent oil pump regarding wet sumping. So maybe someone can add info about newly installed oil pump and wetsumping then ? I had wetsumping with the Guzzi and Horex oil pumps but that was cured by overhauling them to perfect fits of all components by new bushes in critical places. So would not think a new Vincent pump is likely to wetsump a lot within several weeks ?

Vic
 

Cyborg

Well Known and Active Website User
VOC Member
A new pump carefully installed “should“ be just fine. In recent history, I have purchased 3 pumps. Although they come (rotor and housing) as a matched set, the clearance was not the same on all 3. There isn’t a lot of surface area to seal off the ports. When one port closes, it’s not that many degrees before the other side opens. This is the area that will likely get the most wear from any swarf circulating in the oil. Then there are the installation problems. Worst one seems to be the outer race of the small roller isn’t where it should be and the pump housing gets damaged during removal or installation.
 

Marvel

Website User
VOC Member
I fitted a tap in the supply from the oil tank to the pump on the Series A to stop it wet sumping as it would overflow into the chaincase. So I don't forget to turn the tap on I plumbed in a nice pre-war Smiths oil pressure gauge. According to the book it should use 50 grade oil during a temperate summer and 30 in a temperate winter. When starting from cold the oil pressure is about 25psi dropping to 5psi when hot. Changing from 50 to 30 grade oil reduces the cold pressure by about 5psi in the same ambient.
 

Bill Thomas

Well Known and Active Website User
VOC Member
I like that idea, But I don't think we have enough oil pressure on "B" s "C" s And "D" s ?,
Anybody tried it ?,
I went all the way to Devon , For a Hill Climb / Sprint, Years ago,
Looked in the oil cap on the start line !, No oil return !.
I know it will run for some miles with out oil return, But it would be nice to have a clock to see ?.

That's all I can do , Is check whenever I start the bike for a ride, There is oil returning.
Cheers Bill.
 

Monkeypants

Well Known and Active Website User
VOC Member
When I bought my Rapide I had all sorts of ideas (not all my own ideas I should add) about solving all those problems and the many horror stories I had heard about... and many of the solutions, I'm glad to say. I found were not applicable to my bike.. I bought from Conways their anti sumping valve, a beautifully made and (probably) easy to fit part. However, I decided it was not the prettiest thing to hang off the side of the engine (although it could possibly distract, only slightly, from the hideously ugly, in my opinion, Elephants Trunk breather! I figured Any breather must be better than that, sorry) So, I have no anti sump valve (except in my spare parts drawer) and haven't found a need for one, I'm changing the oil regularly (20-50) and using the bike as often as possible, even in winter, which is quite mild on Tropical Vancouver Island. I should add my 48 Indian Chief has a oil line tap, it's a gas pipe fitting.. The Indian gets little use, mainly because it's not that much fun to ride. I also have a 1991 Harley that cheerfully dumps 3 quarts of oil out of the breather pipe on start up every spring, the 72 Shovel and even the 54 Panhead are much better behaved. The 75 BMW R90S of course is Teutonically faultless
Andrew, I did much the same, ordered the Conway's spring valve then put it in the drawer. My main concern was that it might not open one day. The appearance isn't great either. It does appear to be well made!
The oversized engine required a 2 start pump, not for lube so much as for extra cooling. If you plan to make a lot of extra HP, you should have extra cooling as well, if possible.
The new Maughans 2 start in the 1360 wet sumps quickly. In a week or so the entire contents of the oil tank are in the sump. Very annoying!
There was a report of other owners having the same issue with new Maughans 2 starts.
It seemed that a manual ball valve with some sort of failsafe was going to be needed.
This one is 3/8" right thru.
It uses the ignition key to shut off the oil. With oil off, the key cannot be removed.
This has been very easy to live with. And no oil on the floor after winter storage!
With oil on at top and off below.
Screenshot_20211201-135046.png
Screenshot_20211201-134437.png
 
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Monkeypants

Well Known and Active Website User
VOC Member
Bruce, it's a one off made in the shop here. The valve itself is a standard 3/8 SS ball valve.
I disassembled it and Tig welded the little flanged pieces onto the valve body. Those pieces were made on the mill. Then an aluminium keyfob was milled to fit under the flanges.
It was a bit of a fiddly job, but the end result is there aren't any wires or special little switch needed, or to be relied upon.

Glen
 

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