Topic: 1982 CB650 SC bike barely idles that's it.

[calkirk1]

Hi to All,
 
I have had my 1982 650 Nighthawk for many years, but it has been sitting for a few years. Trying to get it started.
Did a cold start with the choke on and it barely idles, cannot apply throttle without it dying.
My brother and I just rebuilt the carbs and reattached them.  Question: 1. What do I need to do to the carbs now if anything? Do I need to balance them somehow? Or vacuum balance?
   I cut off ends of spark plug wires and it is getting good spark to all four cylinders.
  2. Accelerator pump diaphragm on carb was old and somewhat hardened. We have not replaced that yet. Could that be part of my problem?
  Thanks in advance, Kirk

[Pbeattie89]

Syncing the carbs isn't likely the main problem as long as you didn't change any of the adjustments on the carbs. It may not be running on all cylinders. I would get it running and then disconnect one spark plug cap at a time and see if the idle changes. The idol speed should drop if the cylinder is firing, but if there is no change, then that cylinder is dead. I would then pull the plug and see if it has spark. If it has spark, the next likley issues are fuel and compression. You may need to go back and recheck the carbs. It's super easy to miss a little spec of dirt that could clog a jet.

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[fizzlebottom]

Saying that you rebuilt the carbs doesn't really tell me much. What parts did you replace if any? Did you follow a service manual's instruction? If so, which one? How did you set the pilot screws? Did you measure float heights?

Give some details. I've been in these carbs more than is good for anyone and can help if you tell me more.