Motorcycle Repair: 1980 cb750f supersport not holding consistant idol, silicon rectifier, cb750f

Question
so i was having a charging issue and i took it to a shop so get check out but when i picked it up they had the choke stuck completely open and idling at 2500rpms after i closed it the idol went down to 500 and under then stalling. my bike completely died and wont start, the starter cranks but the engine wont turn over. so i started testing and found that there was no spark and tested it back to a bad silicon rectifier , i changed that and the spark plugs cuz it flooded when they ran it with the choke open, now it runs but it only idles at 500 or under the stalls. can you offer any info as to where to start troubleshooting,
thanks
mike

Answer
Mike, there could be a number of reasons why it won't idle correctly.  First is it running on all 4 cylinders at idle?  Does it run better if you apply a little choke?  If it does you probably have to clean the carbs. Have you checked the timing and carb synchronization?  If it runs good except won't idle, it could be idle mixture adjustment, carb sync,or ignition timing.  Sorry but with out a little more information, that's about all I can suggest for now.

Regards,
Rich