73 THUNDERBOLT 850 carb

[cpdchap]

Just rebuilt the carbs on my 850. Top end it runs perfect but I kept having a rough idle, no matter how much I adjusted air/ fuel and idle settings. I determined it must be some kind of vacuum leak and went to searching and discovered something interesting. It seems that that the linkage shaft in the top carb has a little play and when you spray carb cleaner at the top of the carb there is definitely a small leak. Has anyone had this issue? When I rebuilt the carb I do not remember any kind of bushing but I am pulling it back off. I figured it's either the shaft is worn or the actual carb body is worn, if it's the carb body I will probably drill it out and put a brass sleeve in and if it's the shaft see if I can get one..........just curious if anyone has dealt with this.

 

[Chris1956]

There is no bushing. It is brass throttle shaft to aluminum carb body. I would simply adjust the idle mixture to compensate. You did clean the entire idle circuit, right? There are pinholes in the carb throat that need to be clean. The float and inlet needle are new? The gaskets are new? The carb throttle plate open at the same time? There is an adjustment for that.

 

[cpdchap]

Well Chris, I would like to tell you I did a perfect job on the rebuild, yes I did clean out the pinholes and the idle curcuit. But I am pulling it back off and will recheck all of it........hadn't thought about compensating with the mixture. I did find another carb body for pretty cheap so I might go that route. Thanks for the input.

 

[Chris1956]

That carb will have an "Idle restrictor" tube under a brass plug on top of the carb. Try to remove the plug and blow it out.

 

[Faztbullet]

Thats the idle tube and they do crack and that canroug idle as will a low float setting...