Oil

The Norton engine is a dry sump design, apart from the oil that is circulating and lubricating, oil is stored in a remote oil tank - not in a sump at the bottom of the crankcase. A wet sump design stores the oil in the engine cases, there is no separate oil tank.
Nortons are prone to oil draining from the oil tank into the crankcase if left standing for a while, this is referred to as wet sumping.
There are threads discussing why this happens and various cures and as usual there are lots of opinions and lots or right answers.
The simplest cure is ride often.

ntst8 is absolutely right - if you ride every day, the small ammount of oil that will dribble into the crankcase will not cause any problems. If you ride once a week it is best to remove the little crankcase drain plug, catch the overflow in a clean jug, then pour it back into the oil tank.
I have tried SAE50, SAE40 and 20W/50 engine oils. They all wet sump. I have painstakingly lapped the oil pump in on two separate occasions, the second time using new gears from Mick Hemmings. It still wet sumps.
I am loathe to fit an anti drain valve, since that seems like a disaster waiting to happen, so I continue to drain off the crankcase before every ride.

I'm lucky that's not a major problem on mine. It sumps a little but if I leave the crank at TDC after every ride it stops the worst of the leakage. The theory I guess is that the oil finds it more difficult to leak uphill for some of the time. Even though the oiltank bottom is still higher than the rod journals at TDC so it's not a long term solution. I use Amsoil 20/50 synthetic which is pretty thin cold but most of the drainage happens straight after a run (even thinner).
I lapped the pump 12000 and 18000 miles ago after a crank regrind and with the engine apart for new mains and ISO alignment work it still has no end play on the main shaft.
Worn rod bearings and journals will likely make it worse, even if they aren't knocking. Prior to a blowup in Oct '02 and with the pump lapped it used to sump terribly, even with straight 50. Just a thought.

I am one of those who rides only once a week and have noticed the bike does wet sump. Sometimes only a fraction of oil showing on the bottom of the dipstick so I have just started the bike as normal, the oil soon returns to the tank. Will this cause any damage to the engine or will I have to drain and refill the crank cases before each ride?

Neil

Neil said:

I am one of those who rides only once a week and have noticed the bike does wet sump. Sometimes only a fraction of oil showing on the bottom of the dipstick

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If there's oil showing on the dipstick provided that it isn't just the tiny amount that gets left behind when the oil level drops below the end of the dipstick (a visual check inside the tank is better) then I wouldn't worry.

However, (as I see it) if the level has dropped to the point where most of the tank strainer gauze can be seen (then logic would dictate) that the oil feed pipe between the tank and engine is likely be empty (the gauze strainer not being at the very bottom of the oil tank so the tank will never completely empty) so, on start-up, the pump will be pumping air instead of oil for some seconds until the scavenge system starts to refill the oil tank, how long it takes the (cold, thick) oil to then get from the tank to down to the pump I have no idea or whether this has any effect on engine life or not!

So it could be worth leaving the crank at the 'compression' position, not just because it can slow the rate that the oil drains down, but at least a certain amount of oil should remain trapped within the crankshaft oil gallery. The gallery itself is quite large so if empty it will take time to refill.

Personally if I know I will not be using my Commando for a while then I tend to remove some the oil from the oil tank with a suction gun, this looks like a large syringe but works in reverse (cost about £7-£10 UK) and I then use the gun to transfer the oil to a clean container. I had to fit a 'restrictor' nozzle to the suction gun pipe as it can be a little bit messy otherwise.
http://www.machinemart.co.uk/product.as ... 107&r=2056


I find using a suction gun is a lot less bother than continually draining the oil from the sump (and the wear on the crankcase drain bolt threads that can result from that).


All you have to do is remember to put the oil back into the tank again, before starting which, provided that the rider gets into the habit of checking the oil tank before starting (if they don't already?) then that shouldn't be a problem, and I never remove all the oil from the tank anyway.