Smoke on start up...

What side is it smoking from, it could be wet sumping. 

If you stop and think about what the possible sources of the smoke are you can come up with only a couple.....

Rings

Guides

It will be a process of eliminations until the correction is made.

Which side is the smoke coming from?

p.s. When you park up your bike are you using the sidestand or centerstand?

I have read here that when on the sidestand  oil can gravity to the guides on the low side???

Mike

Drain the sump before starting, if the smoking does not happen then carry on draining the sump before each riding day or leave the surplus oil in the sump and live with the smoke.

Chris

My Mk3 also smokes from cold on the righthand side, more of a haze rather than clouds of blue smoke which I have experienced with a split inlet valve stem seal and is due to a forged piston seizure 4 years ago (insufficient clearance) I had the bores honed to a final 0.0055" clearance and fitted a spare set of new pistons. Photo below shows the cylinder before honing.

There were still slight score marks on the righthand side after the hone and possibly these account for the haze, but like yours, disappears fairly quickly on warm up and oil consumption remains good. It also wet sumps but I don,t worry about that, just take it easy until the engine is warm then go for it. The valves, seals and guides are in perfect conditon and the plugs aren,t oily so if your engine is similar it could be rings but if it doesn,t get worse it may be OK. My bike used mostly on the centre stand.

My nephew rode it this summer on one of our runs and when a friend following on his Thunderbird 900 mentioned he was really giving it some revs with no visible smoke he assured me he only exceeded 7000 rpm a couple of times.

P.S.    Phil,s comment reminded me that a regular oil level check after a long run when the hot engine oil has stabilised to your chosen level then rechecked before a cold start, is a simple way of keeping track of oil consumption or wet sumping. I keep to the H mark with a standard Mk3 dipstick.

It wet sumps sometimes and then not at all despite a strip down and surface plate refurb of the pump parts a few years back, also replacing the seal and Mk3 anti wet sump valve parts. Possibly due to the random TDC effect of the engine at rest some people mention. An oil and filter change last week saw no level change at all after sitting for 10 days until I started and test rode it yesterday before final top up.

Your engine may be displaying the classic signs of wet-sumping due to a worn oil pump.

If you Commando has covered more than 50,000 miles then the chances are that the oil pump is worn internally and in need of a service. The original Dominator  pump was designed to last 100,000 miles but with the bigger engines came the double speed gearing which of course wears the pump out much quicker.

Hello It's Not Just  Norton,s  That Smoke On start up  many Diesel engines and petrol engines  do smoke on start up  as an engine is left for some time  there is a build-up of oil around the rings  and valves areas  and this after startup then burns off  when the engine is warming up  So nothing much to worry about,  just ride and enjoy    yours   Anna J