Topic: 1973 cb350f, cylinder 4 no spark

[751]

 Hi guys! I went to get my cb350f out and it starts but runs funny, It has great spark to cylinders 1,2,and 3. Cylinder 4 is dead, plug is wet but no spark, I have looked over the connections and everything looks ok. It has new plug caps put on last year. My guess is a bad coil, Any of you guys experienced this? Thanks!!!!!

[jessezm]

If the coil was bad you wouldn't be getting spark on #1 either.  Check the plug boot and wire.  if you pull the boot and put in a plug and lay it against the head and start the bike, do you get spark at the plug?

[ChortlingSandcaster]

If the plug is wet you're getting gas.   First do this simple test.  Take a sparkplug out of one of the working cyclinders and put it in the dead cyclinder.   Does that fix things?   Will take you 5 minutes if you just swap #1 for #4 plug.  Let us know!

ps. if after you swap it the 'formerly working plug' from #1 is also now wet and the cylinder is still dead -- check the choke plunger for that #4 carb if there is one on your 350 and make sure the choke plunger for that carb isn't stuck on.  Disclaimer here is I don't know exactly your bike's carbs but if the carbs have an individual plunger and it is stuck 'open' on the #4 carb, that can flood the # cylinder and foul out the plug.

Let us know about the spark plug test!

[751]

  Thanks guys! I found out that one of my new plug caps were bad. It was idling and i bumped it with my hand and she started idling fine. Pipe 4 got hot real quick, Replaced the cap and it idles fine. I cut 1/4 inch of the ends and used dialectric gease also before assembling. Thanks!