Norton Commando
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Smoky engine

 
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chiefdeal



Joined: 10 Sep 2008
Posts: 2
Location: East Lothian Scotland

PostPosted: Wed Oct 29, 2008 2:04 pm    Post subject: Smoky engine Reply with quote

Hi to all, first post.
Any hints in telling wether its rings or valve guides with engine running?
'73 850 interstate.
Also, any commando owners in East Lothian?
Cheers
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ML



Joined: 29 Jul 2007
Posts: 48
Location: Melbourne, Australia

PostPosted: Wed Oct 29, 2008 7:37 pm    Post subject: Reply with quote

As a general indication, ride the bike and observe if under accelleration blue smoke increases then its most likely to be piston rings. When decellearating quickly, i.e. throttle off, coast and then blue smoke emits its more likey to be inlet valve guides or their seals.

This road test is more informative than a static test which can depending on how bad the wear is can also indicate what's most likey to be the problem. However, the very least is the head has got to come off so with the exposed cylinder bores you might also get a visual clue as to the probability of the rings being worn as well.
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ludwig



Joined: 30 Aug 2006
Posts: 113
Location: belgium

PostPosted: Thu Oct 30, 2008 12:50 am    Post subject: Reply with quote

Ride the bike 15 min. to warm it up .
then block the oil feed line to the head by using a plain bolt .
Ride the bike like this for 5 min . and see if the smoking stops , or not .
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BrianK



Joined: 14 Jun 2007
Posts: 415
Location: Boston, MA USA

PostPosted: Thu Oct 30, 2008 3:17 am    Post subject: Reply with quote

You can also run a compression test "dry," in the usual manner, and then "wet," after adding a tablespoon or so of oil to the test cylinder. If compression is higher "wet," it's more likely rings than valve guides.
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batrider



Joined: 09 Aug 2008
Posts: 49
Location: Upper Black Eddy, PA USA

PostPosted: Thu Oct 30, 2008 3:32 am    Post subject: Reply with quote

Another thing to keep in mind is that if smoking on trailing throttle or at idle, the guides and seals can be fine but they can have excessive clearance in the head, with oil going down the outside of them. There is a lot of vacuum with the throttle shut which will try to pull any oil sitting on the floor of the intake rocker box into the combustion chamber.

Now that our bikes may have a had a number of guide changes, this problem is getting more common.

Russ
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chiefdeal



Joined: 10 Sep 2008
Posts: 2
Location: East Lothian Scotland

PostPosted: Fri Oct 31, 2008 3:07 pm    Post subject: smoky engine Reply with quote

Thanks for the replys, it will give me something to go on. Excellent site by the way.
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The Unapproachable Norton Commando

At the end of 1967 the Norton Commando was announced.

The Norton Commando was greeted with a certain amount of scepticism because on first sight the commando appeared to comprise of the old Norton Dominator twin cylinder engine mounted at an inclined angle in a set of new cylinder parts.

It was not realized that the new Norton Commando Isolastic method of engine suspension damped out all engine vibration and produced a machine which had uncanny smoothness for a vertical twin. In due course the critics were silenced and the Norton Commando had the distinction of being regarded as the first of todays so called superbikes. There can be little doubt that the original design concept of the Norton Commando has proved correct, since comparatively few modifications of any real consequence have been made since production commenced during 1968.

Now nearly 40 years later Norton Commando riders like us are a breed of our own, and as far as we are concerned its still more fun to go for a blat on the old Norton Commando, and fast. As a Norton Commando owner and enthusiast, my goal here is to promote and give credit to those who keep the Norton name going.

It is more deserving to give credit to the Commando itself, for after all these years it continues to be respected. The original Commando designers like John Favill are those who deserve the credit for developing this incredible motorcycle.

The Norton Commando Roadster and Interstate of the late seventies, never died. Although the Norton Villiers factory dispersed the tradition lived on. Today Kenny Dreer in the USA is developing the new 952 CC Norton. What a great looking bike this is, and its engineering is still based on the original layout. It will be interesting to see how the new 952CC Norton does in todays tough motorcycle market. One thing is for sure, I would own one if I could afford it.