Norton Commando Q and A with Keith


| 8/7/2020 3:13:00 PM


Commando revival

Question:

Hello, Keith, maybe you can help me. I bought an all original 1975 Norton 850 Commando from a woman whose husband had passed away. The bike has 2,750 miles and is a one-owner machine. It appears to be 100% original and was last inspected in 1995. I have cleaned it up, replaced the fluids and some gaskets, cleaned the carburetors and more. I did all the things that I thought should be done to a bike sitting for so long. It was in very good condition for its age, sitting in a dry garage with little heat. I cleaned the gas tank, put a new battery in it and it fired right up. All the lights work. That was a month ago. It idles great, but above that, it misses constantly with dry sooty plugs, both are exactly the same condition every time. I must have pulled the carbs 5 times just to check again and again. It has new coils, condensers and points, and the timing is dead on. I ran it without the mufflers on and there was no difference. I must have read the shop manual a couple of times. I was about ready to give up until I saw your posts. Please help.

 Mike Glessner/Levittown, Pennsylvania

Answer:

Well you’re probably not going to like hearing that I think you need to pull the carburetors off, yet again, just to check that the jets and needle haven’t been changed over the years. The recommended settings changed from 1974 to 1975 and the main jet and needle clip were specified leaner. Make sure you have the correct needle. The Commando needle has 4 small grooves above the 3 needle clip grooves and the needle clip should be in the top of those 3 grooves (leanest setting). The main jet went from a 260 in 1974 to a 220 in 1975, again a leaner jet. The reasons for these changes were to meet emissions standards and to accommodate the more restrictive airbox and exhaust.




engine

cjbelling
9/18/2020 9:18:39 AM

I need some help. I had a frame off restoration done on my 1975 Mark III Commando. The engine was rebuilt with a Megacycle 560-00 cam and Black Diamond valves at one shop which then stopped work for 4 years (much to my displeasure). I reclaimed it in 4 large totes with a rolling chassis. I took it to a very reputable shop (albeit 400 miles from where I live) for powder coating of the frame, triple trees, etc., and re-assembly. The bike is equipped with a single Mikuni carburetor. The second shop was great and did an amazing job, BUT, when I got the bike back it ran GREAT for the first 5 miles. Then it started to surge, then fouled out the left spark plug, then died. The second shop did say it was running rich (by plug read), but they couldn't correct the rich condition and apparently didn't test ride it far enough for it to die. I'm now having the carburetor completely rebuilt and crossing my fingers. If anyone has any thoughts please e-mail me at cbelling@roadrunner.com. I really want a reliable Mark III. Thanks.


Nortonaround
9/10/2020 9:20:47 AM

Still have mine from new when I bought it in Phoenix AZ in1975. Runs great! Sleeving the carbs and adding the "Olde Britts" style electronic ignition was a real game changer...the bike runs fantastic as it continues to pull through any RPM range! (mine has 55K miles on it.) I also put a 4 brush style geared up starter on it. It starts as good as any modern bike!


Kevin A Coffey
8/29/2020 7:18:40 AM

Very nice machine but not a quater mile contender




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