73' Norton Mark I Running Rough

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Tornado said:
stepped main jets
Click to expand...

Stepped spray tubes, main jets are as normal.

73' Norton Mark I Running Rough
 
MexicoMike said:
My money's on a vacuum leak! (Since I don't have any money, this is not a concern - spent it all recently on a guitar.)

Usual suspects are:

1. Leak at the intake manifold(s) to carb(s) or intake manifolds to head.

2. Balance hose between the carbs not sealing.
Click to expand...


And MexicoMike in for the win!! Looked at the balance hose and it had completely come off the left carb. Pushed it back down and back in business....wow all that for that, ha. Thank you all for your help!!!! So no clamps on those or anything?
 
Hey! Glad it worked out to be something simple AND free!!! The Norton parts diagram does not show clamps for that application and I have never used them but it certainly wouldn't hurt if you decided you wanted them!
 
Eric Bauer said:
And MexicoMike in for the win!! Looked at the balance hose and it had completely come off the left carb. Pushed it back down and back in business....wow all that for that, ha. Thank you all for your help!!!! So no clamps on those or anything?
Click to expand...

But, that should in principle affect both sides from running correctly...as air can now enter both manifolds.
 
Tornado said:
But, that should in principle affect both sides from running correctly...as air can now enter both manifolds.
Click to expand...

Correct - I had tweaked the carbs trying to fix it and put them both back to their original settings which I left out
 
Eric Bauer said:
Correct - I had tweaked the carbs trying to fix it and put them both back to their original settings which I left out
Click to expand...
So maybe you had tried to compensate bad idle by carb tweaking before discovering air leak. Getting one side out of balance to other. Makes more sense.
 
Tornado said:
So maybe you had tried to compensate bad idle by carb tweaking before discovering air leak. Getting one side out of balance to other. Makes more sense.
Click to expand...

thats correct, exactly what I did. Although to your point it is weird that one side was effected so much more than the other. Any thoughts? Also weird it just popped off - I need to read up on what it does.
 
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I like simple solutions.
However, I agree that opened a vacuum leak to Both Sides. Both should be affected.
I use a small zip tie as a clamp.
 
I had it happen in my early days of ownership. Back when I had a Boyer Ignition. As I recall, I had experienced
occasional kick-back, probably meaning the timing was not optimally set. A back fire will easily blow one of
the balance tubes off of it's spigot. No problems since installing a Tri-Spark ignition. I have not needed to ever
use clamps on the balance tube.
 
Do you guys have know the best size and / or material for the balance hose? This one keeps popping off and one side is just really loose - I could clamp it but it just seems like it's worn out - not experiencing any kickback but it still pops off from time to time. Last night it flew off after a strong kick.
 
Standard automotive vacuum hose - I think it's 1/4".
 
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I just grabbed some 1/4" windshield washer hose I had kicking about in a drawer and it is a good snug fit.
 
Can’t remember ever having one come loose or fall off, ever.
 
lazyeye6 said:
I had it happen in my early days of ownership. Back when I had a Boyer Ignition. As I recall, I had experienced
occasional kick-back, probably meaning the timing was not optimally set. A back fire will easily blow one of
the balance tubes off of it's spigot. No problems since installing a Tri-Spark ignition. I have not needed to ever
use clamps on the balance tube.
Click to expand...
4 strokes suck, bang blow, I think there's an irony in there, somewhere . . . . .
 
It had a crack in it upon further inspection so we shall see of changing it works...praying to motorcycle gods.
 
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