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I think the blue smoke comes from leaking inlet guides when running.
I had a BMW K75 recently & if they are left on the sidestand, oil drains past the piston rings into the combustion chamber.
That causes a lot of white smoke for quite a while. Somehow, oil is leaking into the combustion chamber when stood still.
Could be the guides.

Flo,
If he has oil coming past his piston rings on park up he may need to start parking with the sump at the bottom of the engine ,

Hi, I had problems with the same smoking after start-up and it was the copper head gasket I used leaking oil into the cylinders. Good Luck

You don't have a family of white mice nesting in your mufflers, do you?

Might not be smoke.

No, what I meant was that oil getting into the combustion chambers will come out in a white cloud.
I am not suggesting that the Norton is parked up a wall or on it's handlebars. (that was a joke, not sarcasm).
Wonder if his engine breather is anywhere near his intakes.

raw fuel

I reckon this is oil getting down the exhaust valve guides and evaporating in the exhaust gas down the port. Seen this a few times on bronze guides in alloy head Mercedes Benz's. As the motor warms, the problem can get better or worse depending on the grip the guide has in the head. Burning oil is a blue smoke, where non-combusted but super heated oil is white smoke. As described in the earlier emails, you said the plugs where normal brown and dry so I can only assume its getting by the exhaust guides. Do you know how or if the exhaust guides where replaced? The proper tool and procedure is pretty essential in a Norton head.

Mick

>>Burning oil is a blue smoke, where non-combusted but super heated oil is white smoke.<<
Mick[/quote]

When you see propellor driven aircraft in airshows leaving trails of white smoke it is generated by squirting oil onto the exhaust manifold.
I agree this doesn't sound like a burning oil problem and I'd bet your call for leaking exhaust guides is it.

or possibly rings!

Seeley920 wrote:or possibly rings!

If it were rings, the plugs would be oily.

not necessarily! I've had a motor with a blocked breather pour white smoke out of the exhaust....plugs weren't oily!

Should I assume that a blocked breather would ordinarily drive oil into both combusion chambers equally, or could also result in only one chamber burning oil ?

It's a Norton, anything is possible! I've seen one bore wear much more than the other on some motors! If the bikes on it's sidestand, who's to know where the oil will get splashed!

It's a Norton, anything is possible!

and

If the bikes on it's sidestand, who's to know where the oil will get splashed!

Try less oil in the oil tank

My Commando used to do this.

http://www.nortonmotors.de/ANIL/Norton% ... 13&Part=45

Breather on mine goes into the back of the airbox, Black smoke is carbon because it is running too rich and white smoke is oil.

Could be valve guides, could be piston rings, could be head gasket, but it's a Norton so check simple things first.