cb400 nc31 wont start

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urbantiger
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cb400 nc31 wont start

Post by urbantiger » Wed Apr 13, 2022 10:05 pm

hi all...
my mate has a 95 cb400sf nc31 50th anniversary model...
it wasnt used for a few years..
got it running for him...
bike would start ok...run great then now and again bike just quit..seemed to run better with fuel cap open..
so anyway i removed tank and fuel tap..
fuel tap was clogged with a grean powder substance... old fuel laying in bike for years..so i cleaned the fuel tap..blew out the fuel cap breathers..
removed carbs and gave them a damn good cleaning...
noticed restrictor washers in the intake manifolds... my mate says he was surprised they were in there as when bike did run it ran really well and pulled strong..
i removed the washers ..
bought a carb repair kit from china..
fitted the complete kits apart from the needles as originals were fine..
main jets in the kit were 105 and i think 40 pilot jets..
mixture screws set a 2 turns out...
balanced carbs..
new plugs fitted...
new air filter fitted..
cant get bike started... i have spark and fuel going to carbs...
now and again backfires in exhaust and can hear popping in airbox with filter removed..
coil wires connected correctly...
now strange thing is i switched over the coil wires..and bike started on cylinders 3 and 4... i know coils fire cylinders 1 and 4 and 2 and 3..
ive built many carbs over the years but not had a bike fail to start after fitting repair kits...
any ideas guys?


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