Wet sumping commando

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hayabusaman0

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Hi All, My 850 drains most of it's oil overnight into the crankcase. Iv'e pulled the timing cover off to check the oil seals & camchain adj, I might as well change the seals while it's off, is there any thing else to check while I am in there? Also I need a rear brake drum(mine is hooked & the paddles are loose) where is the best place to buy(UK)?

Thanks in advance, Hayabusaman.
 
Give your oil pump an overhaul to get rid of the clearance the oil leaks through, also look at modding the timing cover to put an spring and ball in to further reduce the oil flow, as its after the oil pump its the best position for a check valve.
 
hayabusaman0 said:
Hi All, My 850 drains most of it's oil overnight into the crankcase. Iv'e pulled the timing cover off to check the oil seals & camchain adj, I might as well change the seals while it's off, is there any thing else to check while I am in there?
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Use monograde (SAE 40 or 50) oil.

As advised, lap the pump to remove all end play (see your workshop manual) lapping the pump should be considered a periodic maintenance task, not only to reduce the rate of drain-down, but also to maintain pump oil pressure.

Always leave the crank positioned around TDC, as then the oil has to climb 'uphill' slightly to escape! It's not a cure, but it can slow the rate of drain.

If the timing cover gasket (or sealant, if used in place of a gasket) is not sealing around the pressure relief oil way drilling properly (MkIII models don't have the drilling in the cover, but still have it in the cases) then the oil will simply drain out at that point, as the drilling is directly connected to the oil feed from the tank.






hayabusaman0 said:
Also I need a rear brake drum(mine is hooked & the paddles are loose) where is the best place to buy(UK)?
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As you are in the UK there's no shortage of Norton parts suppliers. http://www.nortonmotors.de/ANIL/Distributors.htm

My first choice for parts would be Mick Hemmings: http://www.mickhemmings.com/

Then either RGM Motors: http://www.rgmmotors.co.uk/
or Norvil: http://www.norvilmotorcycle.co.uk/
I expect the others on the list are good too, but I've never dealt with them. [Edit] (actually, that's not quite true, as I've bought Triumph parts from TMS who always gave good service).
Or you can buy parts directly from Andover Norton: http://www.nortonmotors.de/ANIL/Norton% ... s-list.php
 
Thanks LAB, I have been told that to reverse the gear selection all you have to do is turn the camplate round, do you know if this is correct?
 
Sorry guys, this is not going to work out. You have to regrind the camplate in order to switch from up to down gearchange. Grind 5 new notches 180 degrees opposite.
 
I have to say that I love the original setup on the gear lever. But then my first bike was a BSA B33 and my second was the 70 Commando. I had a 500 Honda in between and could not stand it, was always looking for the correct gear on the wrong side.

My Problem

Dave
69/70 S
 
Don't know of a Commando that doesn't wet sump, unless it has a one way valve in place, or some other mod to stop the oil seeping past the gear sides in the pump. Personally I would not put a check valve in place, as I would worry it may restrict the flow of oil at idle and also it may fail by locking and restricting flow (unlikely, but possible).
If you carefully re-build your pump and keep the crank at TDC after riding, it should not wet sump overnight, mine seems to hold up for several weeks, if not more. I use 20-50 oil.
The most interesting mod I saw was a simple ball type valve that, when shut, the handle covered up the ign switch where the key went in. So you shut the valve when you stuck it away but couldn't get the key in until you opened the valve.
Stu.
 
"Don't know of a Commando that doesn't wet sump, unless it has a one way valve in place, or some other mod to stop the oil seeping past ..."

I agree.
 
L.A.B. said:
Use monograde (SAE 40 or 50) oil.
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I wonder how much wetsumping is caused by the multigrade oils? The properties that make it "thinner" when cold are also going to allow the oil to seep through the pump and other orifices easier when sitting.
 
Don't always believe what has been written. Just reversing the standard camplate (with 5 notches) won't do the job to switch gearchange from up to down. Everyone who tells you it can be done by only reversing the plate, is seriously mistaken!
 
I have a buddy with a 72 Combat Interstate and he says that even after riding his bike 50 miles the oil level is below the dipstick. He can see oil returning to the tank when running, but the tank never fills up. Does this mean that the suction side of the pump is working harder than the feed side? Is this something that lapping the pump can cure?

I checked prices for new oil pumps around the web... ouch. :shock:
 
Mine wet sumps a little, but I've found its only about 50 cc or so a day. As long as I ride it every other day, it isn't an issue at all :wink:
 
maylar said:
Does this mean that the suction side of the pump is working harder than the feed side?
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The oil pump is designed so that the "suction" (return or scavenge) side has a greater flow capacity than the feed side, so that it is always able to clear the sump faster that the feed side can fill it, otherwise if the flow rates of the two sides were equal, and engine started with a sump-full of oil, it would never empty.
 
L.A.B. said:
The oil pump is designed so that the "suction" (return or scavenge) side has a greater flow capacity than the feed side, so that it is always able to clear the sump faster that the feed side can fill it, otherwise if the flow rates of the two sides were equal, and engine started with a sump-full of oil, it would never empty.
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OK that makes sense. So if the feed side is weak the oil will never return to the tank? Is the Norton oil pump always able to be reconditioned (assuming no broken gears)?
 
Maylar, like L.A.B. said the RETURN side has a greater flow than the FEED side. So if the RETURN side is weak the oilflow might not be enough to fill up the tank. The oilpump body also can be damaged. Especially the 1972 Combat pump as this model has no large sump filter so all the rough pieces directly flow into the pump!
 
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