running really rough

[trikeboiler]

Hi all, little bit of help needed please. eventually got my cb750kz 1979 to fire up, she had been stood for about twenty years, when I got her I removed the carbs and cleaned them through, replaced anythingthat looked suspect, new intake rubbers and clamps, new plugs, filters and oil, and new cdi units ..Now my problem is that she fires up quite easy but I have no control on the revs, it runs at about 3thousand revs then dies and stops, I can then start her again and keep it going as long as I keep it above 3000rpm. now I didn't balance the carbs nor have I checked the timing yet as both procedures ar a bit tricky when I cant get her to tick over. Has anyone got any ideas what the problem could be. Oh and its only firing on three. Thanks.

[motogrady]

I'm thinking the carbs need going over again. Or a vacuum leak somewhere.

I'd swap the spark plugs around first, same problem with same cylinder, do the carbs again, special attention to the problem carb.

[OnyxWolf]

I had a similar situation. A full rebuild of the carbs and adjustment of the air full mix set it strait. Make sure your boots are all seated properly too. These carb are dependant on proper vacuum.

[trikeboiler]

Hi, and thanks for the replies, just been out to have another look at the rubbers from the air box to the carbs and discovered that the cylinder that's not firing, the rubber is not seated to the air box properly and another looks a bit suspect. So when I get chance I shall get them reseated and let you know the out come, I will try anything other than take the damn carbs off again. Cheers all.