Was your friend on the Suzuki's bothered about the smoke? He was probably enjoying the ride.

My ex-police Commander might be similar to the bike you are considering. The engine oil is constant loss metered through a posilube two stroke pump. Just like the Suzuki. More throttle, more oil. They are linked. 

Left standing for a long time, oil finds its was past the pump and into the engine. My pump may be a bit worn at 81,000 miles. First start in the spring can be a bit hazy. 

Mine smokes if I have been bimbling along for miles and have to stop quickly, particularly on a downhill. Oil pools somewhere and gets chucked into the engine on hard stopping. 

All perfectly normal and if you are riding the bike, perfectly acceptable. 

I use Shell rotella, a mineral oil. Some say the alternative Fuchs Silkolene 2T smokes a bit less, but it costs much more. 

A great ride, totally smooth, but to those following....? 

Peter

My Commander uses around 1 litre per 600 miles. If I take into account the fact that my Commando burns some oil and has frequent oil changes, the overall oil consumption is not that different between the two. 
The Commando smokes at first but soon settles down.

Though I know very little about the Commander I do think it is a cracking bike.

Has anyone tried synthetic oil? synthetic oils burn really well and I believe it's to prevent blocking exhaust filters and cats'. The clean burning of synthetic oil might not leave a smoke trail and perhaps even give a little more power and economy?

A little thought on alternative oil for the rotary:-

Synthetic Rotary Oil

A review of correspondence from NOC-L

A synthetic alternative to Rotella

I gave up using Shell Rotella as soon as I brought my F1 back from the UK. Single grade Rotella is hard to find here in the States; most of the truck stops carry multiweight Rotella. I have switched to Redline Synthetic 2 stroke racing oil.

It has a lower ash content, smokes less, has a higher temperature breakdown point, doesn't seem to foul the plugs, and lubricates better, but is more expensive. But on a bike as rare as this, I'll put my money into the best lubrication possible. I've used this for about 18,000 miles with out any problems. The side plates have been moly coated as well.

Thomas W. Kullen (utahnorton@sisna.com) on NOC-L 14th. Apr 1998

The above-mentioned Fuchs Silkolene 2T is a synthetic oil and I believe the only one that was approved by the factory. Mr Negus told me it doesn't coke up engines as much at the mineral alternatives and protects the internals much better when the engine is laid up.
The data sheet for Redline Synthetic 2 stroke racing oil doesn't specify the weight. SAE40 is the approved spec. Whilst the Silkolene is still available, it would be foolish to experiment with anything else. 

A 4 stroke smokes if the rings/bores/inlet valve oil seals are worn, so it's a sign that the engine needs attention. On the Norton rotary, the air is sucked into the Centre Plate of the engine then it passes though the finned inside of the rotors (to cool them) then it leaves the engine on each side via the aluminium transfer ports (I forget the correct name) and enters the Plenum Chamber (big box part of the frame under the petrol tank, which cools the air down) then it goes through the carbs and into the engine to be combusted with the petrol. The oil is injected (via a Mikuni oil pump connected to the throttle cable) into the cooling air when it first enters the engine and can accumulate there (similar to how oil can accumulate in the crankcase of a 2 stroke). There is then a surplus of oil which is picked up by the cooling air and makes it's way into the combustion part of the engine, hence the smoke. So, on a Norton rotary it's not a sign of wear and giving it a good thrashing should suck the surplus oil through and clear it. The exhausts, especially the manifold, get very hot and in normal use will burn the oil and it should not be visible in the exhaust gasses. This arrangement is unique to the Norton and the Fichtel and Sachs engine it was based on, the likes of Mazda's rotary sucks the air directly into the engine and cools/lubricates the 'underside' of the rotors with oil and not the intake air. The advantage of the Norton method is that it's not churning cooling oil, just oily air an so has less parasitic losses but has poor emissions because it's a total-loss system. Lastly, if you dismantle an air cooled Norton rotary the 'underside' area of the rotor and eccentric shaft will be covered in burnt, tar like remains of the oil (aka Wankel Guano) whereas a watercooled Norton rotary will be covered in clean looking oil because it runs a lot cooler. And, the racers went quick because they sucked the cooling air through the engine and into the exhaust and the air used for combustion was taken directly from outside so was at ambient temperature rather than about 80 degrees C or more.
I worked on rotaries at Shenstone.
I hope that makes sense and helps, it sounds complicated but it's straightforward.

Must be one'o them John Player Nortons.....

My first Norton was an ex-forces rotary.  While preparing it for the road I asked Silkolene for a recommendation on "engine" oil.   They recommended a "high ash content" 2 stroke oil.  This came as something of a surprise, I thought the ash content had been pretty much blended out of two stroke oils?
Anyone know why this oil was recommended?   For the short time I owned the bike that's what I used, no smoke at all from an engine with ~35k miles on it.
Didn't keep the bike long, overall, something of a disappointment.
 

Thoroughly agree with Brian and Robin above. 
IMHO and experience the list of recommended oils from Norton Motors, the designers and developers of the Norton rotary, is the only recommended oil. The lists are in riders manuals and official workshop manuals. 
If you buy a rotary and use an oil outside the list you are into unknown territory with the grave risk of insufficient lubrication and burn residues that will make the rotor side seals, particularly, stick in their grooves. 

On air cooled particularly, the higher engine temperatures will break down a marginal oil film. The lubrication between rotor sides and fixed side plates is critical, and highly stressed. Oil film failure and you are into damaged side plates, which are only alloy. Minor damage to plates is recoverable by metal spraying molybdenum. The "moly coated" is a harder surface than alloy, and a bit more tolerant of marginal lubrication. 

The NOC have a rotary expert, Graham Wilshaw, and his advice will be correct.

The ROC, rotary owners club, have a good forum and is much used by rotary owners. A legacy from the decision by NOC to ditch rotary spares from the spares scheme that did not go down well with some members. 

Peter

Andrew,

I am sure someone will correct me if I am wrong, but the reason the air goes the direction Brian described, is it is the way the rotors are cooled. Without it, there would have to be a different method to blow cooling air through the rotors.

I believe the F1 etc. use the exhaust flow to act as an extractor to pull air through. you can see a pipe going into the side of the exhaust on the F1's.
This means the engine gets cold air and hence better power. But unless you have a good amount of exhaust going out, you will not drag through a good amount of cooling air.

Experts. Is this correct?

The airflow cooling method was done before I worked there, I guess it ws chosen because it's simple and in theory quite clever, other than when the air re-enters it's quite hot. Yes, the racers used a venturi effect in the exhaust so suck the cooling air through and the engine breathed cool fresh air. I questioned David Garside (Chief Engineer) on wouldn't it be better (i.e. more power) if the engine breathed cold air? He said that it's not a problem because the underbonnet temperature of a car with S.U. carbs in a desert is similar to what we had and they work OK. I don't think I made my point very well, it was my first job and I was 20 and unqualified so I shut up.
Excuse the name dropping -  I built air cooled engines and did endurance running on a dynamometer, we cycled at full power for a minute then engine off for a minute with the cooling fan still running, we were looking for a cure for the metal fatigue cracks in the housings that would propagate from the spark plug holes. Each test ran for about 10 hours. The only real cure was water cooling. The engine had a frame fitted on the dyno so that the test replicated the situation on a bike and I pointed out to my boss, Doug Hele, that the headstock end of the plenum chamber didn't help with the cooling because the hot air never went there, it went from the transfer ports straight into the carbs and so how about a baffle in the plenum to make the air go to the cold headstock end?  If you put your hand on the plenum it was cold at the headstock and hot at the carbs. (no petrol tank was fitted though so it wasn't truly what would happen on a bike) His response was to get me a inlet charge air cooler from a Renault 5 turbo which I bandsawed in half and made some aluminium manifolds to fit the two intercooler halves in place of the transfer port elbows. The standard engine made 84 bhp, the dyno was rated at 100 bhp and I blew it up. So my tenuous claim to fame is that I may have inspired Brian Crighton to come up with his brilliant venturi cooling system on the racers that beat everything.
On oil - we only used Rotella. The RAF asked if they could use a military spec. oil in their bikes so I ran an engine on the test bed with it and it burnt to black soot inside the engine before it reached the plenum. If I owned a rotary, I'd get some Rotella.
Brian

When the first rotaries were sold to civilians, Norton recommended Silkolene, but both Silkoline and Rotella were in the manuals. I seem to remember Rotella becoming the primary oil a little later - I believe the preference for Silkoline was that it was more easily obtainable and the change to Rotella to do with race sponsorship (but could be wrong). Either way I'd stick to one or the other. A few years ago the modern Silkolene changed from SAE 40 to SAE 30. Therefore if you go Silkolene you need their Classic 2T Premix to get the old style oil. Silkolene specifically released this oil in the UK from pressure by the Norton Rotary community. The Silkolene is indeed synthetic while I believe the Rotella is mineral.

I've run air cooled rotaries for decades and have stuck to Silkolene apart from a short spell with Rotella (I fully emptied the tank when changing as I was concerned about mixing synthetic and mineral oil). However, the bike seem to run fine on both these oils. You can get a little smoke when the bike first starts (though not always), but it's soon gone. If there is oil when riding then the pump might need slight adjustment. I tend to run my oil pumps just very slightly rich, but it is worth checking every so often to make sure it's not getting too rich (or too lean); this is simple to check and is covered in the manual and the handbook.

I think I do around 500 miles to the litre; I have a Commando too and yes, I use more oil in that than in my rotary...

On Brian's comments about the air flow, he is describing the flow on the air cooled engines. On the Commander I believe the direction is reversed - from outside end plate to the centre end plate, but the principle is the same. I have no idea why the change was put in place...

It may well be that the flow is reversed on the Commander, I had left before they started making them so I don't know. I did build an air cooled engine with 'reverse flow' (Doug's idea) and ran it in a bike. The elbows had stub pipes with K&N filters, there were plates sandwiched between the elbows and the plenum and I made a manifold and modified the frame so the air left the engine at the old intake (where the air filter was) and entered the plenum. The idea was something along the lines of the main bearings saw clean oil before it was cooked by the rotors but I don't remember the details.

Hi,
I have just created these, it shows a rotary with 74002 miles on the clock starting from cold. Started to shut the choke too early hence the pop, but you can see not a great deal of smoke.

One it had warmed up a bit, I did the second video, gave it a handful of revs, again not much smoke.

Hope they help.

https://youtu.be/PJ6YhAuNye8?si=5I5_VBQrF3tunnmi
https://youtu.be/07RdXkxSly0?si=60k63Ur5H7qo4zsH