My *new* 1974 norton 850 starts and dies immediately (2009)

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If the plugs are wet then I wouldn't be focussing on the carbs, personally.

Is there a strong spark from both sides when the plugs are removed, re-connected to the caps and laid on the head?

Is it fitted with points or electronic ignition?
What plugs are fitted? Are they new? Coils good? 6V or 12V?
As Cookie has already said, plugs can foul easily, especially if the mixture is out.

Has the bike ever run in its current form?
 
debby said:
One other thing to check: oil level. If it's wetsumped heavily you can get exactly those symptoms - fires right up and then dies and is hard to restart. My 750 drove me nuts with that when I first got it. I didn't know.

If oil level in the tank is low, drain the sump then top off the tank. Never top off without first running the engine or draining the sump.

Hope that helps and good luck,
Debby
Click to expand...

Didn't even think of that. Will Check!
 
B+Bogus said:
If the plugs are wet then I wouldn't be focussing on the carbs, personally.

Is there a strong spark from both sides when the plugs are removed, re-connected to the caps and laid on the head?

Is it fitted with points or electronic ignition?
What plugs are fitted? Are they new? Coils good? 6V or 12V?
As Cookie has already said, plugs can foul easily, especially if the mixture is out.

Has the bike ever run in its current form?
Click to expand...


Bike ran fine a week (two?) ago in current form... I have only messed with mixture a tiny bit and charged up battery
 
again... (if not done already) go back and pull the bowls/blow out the jets to eliminate at least that possibility of clogging.
 
Start it up with the gas tank cap opened up, if it keeps running then you know the little breather hole is plugged.
 
Matapassiones said:
debby said:
One other thing to check: oil level. If it's wetsumped heavily you can get exactly those symptoms - fires right up and then dies and is hard to restart. My 750 drove me nuts with that when I first got it. I didn't know.

If oil level in the tank is low, drain the sump then top off the tank. Never top off without first running the engine or draining the sump.

Hope that helps and good luck,
Debby
Click to expand...

Didn't even think of that. Will Check!
Click to expand...


Wow, was there ever a lot of oil in the sump - in fact as far as I could tell my oil resevoir was bone dry!

I drained it off and seemed like I was headed for success when my weak spark quit on me completely. I am sure the sump was at least one major component of the problem. Thanks so much for the tip. I do know (i think) how to go chase down a weak spark or no spark at all...
 
highdesert said:
Start it up with the gas tank cap opened up, if it keeps running then you know the little breather hole is plugged.
Click to expand...

I will check when/if I get it to run for more than a second...
 
Matapassiones said:
Bike ran fine a week (two?) ago in current form... I have only messed with mixture a tiny bit and charged up battery
Click to expand...

Interesting!
I'm still curious about your ignition system ;) does it still have the original points with condensers or is it electronic?
 
B+Bogus said:
Matapassiones said:
Bike ran fine a week (two?) ago in current form... I have only messed with mixture a tiny bit and charged up battery
Click to expand...

Interesting!
I'm still curious about your ignition system ;) does it still have the original points with condensers or is it electronic?
Click to expand...

Not electronic yet, but it is about to be!
 
Check the fuseholder if it's oxidized inside. Or spring is weak. If so, change fuseholder. This happen to me this week. Mine would run for a minute and just die. The vibration of the bike running made connection in the fuse holder loose. Then had a connection when not vibrating (engine off). Or you may have a poor connection somewhere else. Worth to check out if not checked.

Jerry

1972 Combat
1973 850 Norton Roadster
1974 850 Norton Roadster
1964 Ford Thunderbird Coupe
 
Matapassiones said:
B+Bogus said:
Matapassiones said:
Bike ran fine a week (two?) ago in current form... I have only messed with mixture a tiny bit and charged up battery
Click to expand...

Interesting!
I'm still curious about your ignition system ;) does it still have the original points with condensers or is it electronic?
Click to expand...

Not electronic yet, but it is about to be!
Click to expand...

Since you have a Commando sitting around in the garage not starting why not get an electronic system now and kill 2 birds with one stone??
 
I posted a comment a few days ago where I thought my fuseholder was the problem. That was not the case. Discovered a broken wire near the terminal that connects to the capacitor and goes to the master switch. Probably from the vibration. Runs good now. Took it out for a 90 mile ride today. Got my fix.

Hope Matapassions found out his trouble.

Jerry

1972 Norton Combat
1973 Norton 850 Roadster
1974 Norton 850 Roadster
1964 Ford Thunderbird Coupe
 
debby said:
One other thing to check: oil level. If it's wetsumped heavily you can get exactly those symptoms - fires right up and then dies and is hard to restart. My 750 drove me nuts with that when I first got it. I didn't know.

If oil level in the tank is low, drain the sump then top off the tank. Never top off without first running the engine or draining the sump.

Hope that helps and good luck,
Debby
Click to expand...
Thanks for diagnosing my problem! Emptied 2 quarts out of my sump! Should have checked oil level to begin with. Started right up after draining. I had removed my anti sump valve recently thinking it led to the recent engine rebuild.
 
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