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Pulling my hair out!!

Andy888

CB750 Member
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Somerset,UK
Hi
i have a 1981 CB750F and I can’t get it to run right. The two middle cylinders run cooler than the outers. When at tickover the outers will be at 120degC and the inners around 60. When riding it feels like it running on 3. It starts immediately every time and idles Ok although it doesn’t sound a smooth as it should.
The bike is running with a new Murray’s twin carb set up. I bought this as I couldn’t get it to run right with the original carbs with pods.



Compression at 150 psi on all 4.
Valve clearances checked and adjusted.
CBR600 coils and relay conversion. (used coils from another bike but ohms ok)
new spark igniter boxes (swapped from side to side)
swapped coils from side to side
swapped the pulser coils for another set
fitted new plugs
Fitted new leads
fitted new non resistor plug caps
the bike has a new lipo battery
the sparks seem to be good on all 4 cylinders


I’m at my wits end and can’t think what else could be causing the problem. What am i missing?.
 
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