At wit's end! Jetting Norton Tech Digest 850 spec, I followed the spec for 850 commando at sea level. Idle is perfect. From around 17-1800 it cuts out badly with any needle setting. Everything is set properly, Cleaned and rebuilt ,tappets, plug gap, fresh fuel, no air leaks. I had changed the jets that previous owner had installed and it had ran the same way. I had bought it this past winter and couldn't ride it due to ice snow. I put a lot of work into it including a sump breather I have spent many hours and shipping time for parts. Any suggestions would be appreciated. Who knows someone may save my sanity.
At wit's end! Jetting Norton Tech Digest 850
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Tornado
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What throttle position on the grip rotation are you at when issue occurs? This will tell you what jets are involved.
I had a stumble just off idle, frequent stalling pulling away from stops, so only 1/8-1/4 throttle roll on, that was due to out of round needle jets and worn needles.
Also had a misfire at about 1/2-3/4 throttle roll on turned out to be a loosening main jet.
I had a stumble just off idle, frequent stalling pulling away from stops, so only 1/8-1/4 throttle roll on, that was due to out of round needle jets and worn needles.
Also had a misfire at about 1/2-3/4 throttle roll on turned out to be a loosening main jet.
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What ignition system do you have, the Boyer has an issue with engine vibration on the wires to the stator in the timing chamber which break internally but work until the revs rise about a set amount.
The choke is opposite to what you expect and a first time owners fault that is easy to fix
so Batrider is right to bring it up.
The choke is opposite to what you expect and a first time owners fault that is easy to fix
so Batrider is right to bring it up.
Tornado
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More details of bike such as what ign installed (points or EI); original wiring? Switch gear?
I had issues with the original ign switch giving flakey starts/running. Others have reported issues from the kill switch. Try bypassing some/all the these to rule them out.
I had issues with the original ign switch giving flakey starts/running. Others have reported issues from the kill switch. Try bypassing some/all the these to rule them out.
Power ArcWhat ignition system do you have, the Boyer has an issue with engine vibration on the wires to the stator in the timing chamber which break internally but work until the revs rise about a set amount.
The choke is opposite to what you expect and a first time owners fault that is easy to fix
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Answer required!
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There can’t be cable play when the choke is off.
No kill switch. Just jiggled switch rapidly and turned back and forth to detents no miss at idle.
I'll check that now.
concours
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Here is relevant info. Sounds like choke is ON.
34mm Mikuni lever
concours
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"The choke on an Amal is basically a lump of metal which restricts the airflow to richen the mixture, and is in the "on" position with the handlebar lever back against its stop. Once you have started the engine, the lever should be wound round fully to pull the choke up in the "off" position, i.e. pulled up into the top of the carb out of the airflow, which is how it appears to be in your second photo. Quite often people can remove the choke from an Amal altogether (remembering to seal off the cable hole) and rely in the tickler for starting."
concours
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Have you VISUALLY VERIFIED FLOW on the Mikuni using aerosol liquid through every air & fuel passage?
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