QuestionHi Bill, I have a 71 CB350 twin that has suddenly developed a problem. Upon acceleration it has an intermitent miss, almost like it is not getting enough fuel, and on de-acceleration is back firing. Can you suggest what to look for? Many thanks
AnswerJules, Could be a number of things....
Check the diaphragm on the carb slide first to see if it has developed a tear or pinhole.
Drain the float bowl to see if there is dirt/debris/water collected there.
Remove the points cover and observer the point motion and look for signs of excessive arcing, which could indicate a failing condenser. Sometimes the condenser mount has corrosion beneath the unit, so it isn't grounding properly to the frame.
Check spark plug cap for a resistance value of about 5k ohms, when removed from the wire.
Check all your connections around the ignition coils for clean/tight connections.
The ignition coils should have about 4.5 ohms measured on the primary wiring sides, with coils disconnected from the circuit.
This assumes that you have properly adjusted valves, the compression is up and even on both cylinders.
Make sure that the point gaps are correct... .014"-.016" (.3-.4mm) and that the right side points are just opening at the F mark on the rotor and left side points are opening at the LF mark alignments. The mechanical spark advancer must be freely moving to advance/retard positions, as well.
Bill Silver
