Topic: Help for 1973 CB350F - Pipes for cylinders 1,2,3 hot but 4 is cold

[nessandpaula]

I have no idea what it could be.  I don't think it is the carbs not giving gas to 4 cause the runoff from that carb drips gas.  all the other cylinders are firing great, but 4 just won't.  Any ideas?  thank you

[Gordon]

If the overflow is dripping gas then either the float is stuck or the valve isn't closing completely.  Either way it's getting too much gas, which would cause that cylinder to not fire. 

[whizzer]

How about unscrewing spark plug caps and if wire corrosion, snip off tad so contact with cap is good.  The cap has a spike that must screw into wire. Eighth of an inch freshens the contact.  This fixed intermittent firing problem on my bike. Could test caps' resistance, too, and replace if worn out.

[flybox1]

If the overflow is dripping gas then either the float is stuck or the valve isn't closing completely.  Either way it's getting too much gas, which would cause that cylinder to not fire.

+1^^  -  fuel level is too high there.
revisit float height/ float valve function, and BEFORE you put the carbs back on the bike, do a clear tube test to verify your fuel level is 3mm below the bowl gasket seam.

[DaveBarbier]

Also just check the plug is firing by removing it and holding against the motor to see if there's a spark.

Motor off, remove plug, reconnect to cap and plug wire, hold threads against motor, fuel off, key and ignition on, crank motor. Best in a dark shop.

Hold it with rubber gripped pliers