Misfiring 850

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Jan 2, 2009
Can anyone help with a misfiring Norton?
Went on long run, 1600 miles, got some duff fuel in Switzerland, and damp weather. Emptied tank, drained carbs and bike seemed OK.
Misfiring a bit due to damp on setting off home, seemed to sort itself out.
On my return home the bike developed a constant misfire when idling. You can hear it on idle, sort of fluffing pop from the exaust, right hand pot only, intermittent, like it is firing every other time. When you increase the revs it starts to misfire more, going onto one pot, eventually the right pot coming back in, at about half throttle.
I have sprayed easy start around the manifold joints looking for leaks, checked the idle jet setting and taken air screw out and poked with wire, taken the slide out and checked the needle is in position. I have also checked the coil connections and also changed the ht leads (swopped them over). I have taken the cover off the boyer rotor stator to check the connections, all seeems OK
Any ideas?
Single or dual carbs?,the wire goes brittle and breaks internaly around about where it goes through the timing cover,a couple of quick jump wires would eliminate that problem, tight tappet? switch the lights on see if it gets worse,{dead battery}
The Boyer is notorious for breaking the coil pickup wires. The wires break inside the insulation near the coils making it impossible to see. The bike will misfire at less than 3000 rpm and then fire on both cylinders after that. There's been a lot of previous posting addressing the Boyer broken wire issue. Just remember the old adage, "90% of carburetor problems are electrical".
Standard dual mk1 amals, brand new (2000 miles).
So connect two external wires from the stator plate up to the black box and see what happens?
I will do this.
Thanks, I will let you know what happens.
Also try swapping the sparking plugs and see if the problem follows.
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