Wet sumping Mercury?

Get your oil pump serviced. There are plenty of threads, on this WebSite, that deal with this issue.

Just look at the wet sumping link thats at the top of the Commando section now.

The fact that you can start it after 3/4 weeks means that the problem is not that bad.

I found that 20/50 oil helped with starting after being stood for weeks with regard to my Commando.

Wet sumping after 3-4 weeks is not unreasonable. Using a multigrade means wet sumping happens faster but the bike will be easier to kick over. Using a straight oil slows wet sumping but of course once wet sumped it's a pig to kick over in low temperatures. BSA had all this sussed long ago - my 1951 A7 doesn't wet sump at all. A shame Mr Hopwood didn't incorporate theBSA solution on Norton twins.

My Mercury is smoking when I start it after 3/4 weeks. Is this just wet sumping and if so what can I do to stop this.?

Do not worrie about it this is normal and your engine is getting oil round the engine just check the oil pressure by just putting you finger over the over flow pipe inside the oil tank if it trys to push your finger of you got good oil pressure, "20/50 the best oil to use , just keep your engine on compession stroke helps, when levening your bike of a long time, oil in the sump is a good thing NOT a bad thing as Your engine can get rid of too much oil in the sump , and it good as this will be doing its job of lubricating well before the oil pump gets its pressure up , you do know that all Nortons were Built Like Steam Locomotives as most engine parts are SLASH Feed . Do not fit tap or any thing inline to stop the oil flow, As they alway ends up in a disaster and your engine's oil is its blood.

Yours Anna J

My SS was wet sumping and alsoleaking a lot of oil on the floor. I consulted Gordon at British Classic Motorbikes at Yatton, Somerset, I think he's also a NOC member, and he reckoned the leak was caused by the wet sumping. Hefitted a non return valve in one of the oil pipes and cured both problems: No more leak and no more wet sumping.

My SS was wet sumping and alsoleaking a lot of oil on the floor. I consulted Gordon at British Classic Motorbikes at Yatton, Somerset, I think he's also a NOC member, and he reckoned the leak was caused by the wet sumping. Hefitted a non return valve in one of the oil pipes and cured both problems: No more leak and no more wet sumping.

And the worst thing that he could of done, this only mask up the real problem, not cures it, so your engine will be going bang any time soon then , Do not take the advise from a marine engineer who been a Norton owner and rider for well over 40 years, yours Anna J