Motorcycle Repair: 82 CBX -no longer starts up, special bike, tv tube

Question
Hi Jan,

Thank you for making yourself available to answer questions on this very special bike and I hope you can help.
I purchased an '82 CBX that has been off the road for a few years.

After going through a cautious pre-start routine that included changing the oil and filter, oil into the cylinders and rotating the crank by hand the bike started right up and seemed to idle and rev normally.  The previous owner had a Honda dealer rebuild the carbs shortly before parking it. I removed the fuel tank and fed the carbs directly, but there was old fuel sitting in the float bowls during storage when first started.

So that day I started it a few times and left it to the following weekend when surprisingly the bike would no longer start for some reason? Fuel appears to be reaching the carbs and I shut the garage door and put the spark plugs, in turn, on the cylinder heads and confirmed that I was getting spark on all cylinders . Albeit the spark looked very weak? As my first CBX I don't know how strong that spark was supposed to look though. The only other detail that I can add is that I "think" I may have heard a "popping" sound from the spark units while I was trying to start it. I think the sound came from the spark unit as I had the seat off the bike while attempting to start it. In some forums I have read posts  about the spark units being prone to failure especially if the bike has been stored for a considerable amount of time. If the spark unit or units (I am not sure which terminology is correct ) failed would I still see spark on all cylinders? Could one of these units make a popping sound (like your favorite TV tube when it dies?). Would the bike still start and run on less cylinders as opposed to not at all?
I guess what I am asking is does this sound like an ignition or a carb problem to you?  Could the bike have started right up and run and then whatever may have degraded in the float bowls plug everything up so it would not start a week later?
I am considering as my next course of action either an "on bike" carb cleaning or replacing the ignition with a dyna unit based on your advice.
I really would appreciate any help you could offer.

Sincerely,
Robert

Answer
Hi Robert,  If you are getting a spark, then I would suspect a carburettor problem,  It is most likely you will need to remove the carbs and get them cleaned out properly.  This is not something that a typical 'on-bike' clean can take care of I'm afraid.  You will need to tilt the motor forward to get the carbs off without scratching things up.

Good luck,  Jan