Carb Clinic

I just upgraded the fusebox today on my 83 XJ750K with parts from Len at xj4ever, great parts, great help and quick and took it for a ride. It runs ok but just ok. I think next is back to the carbs. Is there a carb clinic in the Daytona Beach area that anyone knows of? I rebuilt these and not sure what's gone wrong. It does run and I can ride it but doesn't idle very good, I need to keep the choke on when just sitting and then it starts to run away so I use less choke but then it wants to stall. It sucks down gas, I get about 15 miles to a gallon it seems like. I realy don't want to pull them off and send out or have a local shop rebuild them because that could take weeks. Around here there is plenty of Harley help but not a lot of vintage bike help.
Thanks,
Joe

 

I saw nobody replied, I'm no expert, but here's a thread to start with: https://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/

About the sixth post is one about carbs. CV carbs are awesome when in tune and a royal pain in the tuckus when they aren't.

 

Did you do a bench synch before putting carbs back on ? What are your mixtures screws set at ? Are you running stock airbox ( preferable)? What condition are your intake boots ? Are you running stock jets?

 

Have you checked for vacuum leaks? Try direct spritzes of carb cleaner at the end of each throttle shaft, around the intake boots etc..

 

Sounds like my bike when I got it, but at least I got about 25 mpg. I think your carbs are in bad shape just like mine were. So, here's what I suggest from my own experience. Remove the carbs and remove all jets, emulsion tubes, pilot screws, caps and slides. Boil the carb bodies and everything you removed exceept the caps and slides. Boil for about 10 minutes then blow our all passages with carb cleaner and then blow out everything with air. ( Be sure to make sure all the jets are the correct size, and have not been drilled.) When you put everything back together, open the pilot screws about 1 3/4 turns (more on that later). Wet set the floats. When it starts you will need to sync the carbs. If you get everything clean, and the jets are the right size, the floats are wet set and the pilot screws are set it should start. After syncing it should idle. It you get runaway rpms then you probably have an air leak (mine was the #1 intake gasket). If it runs you will not need to fine tune the pilot screws. Put new plugs in and ride for about 10-15 miles and take a look at the plugs. You are looking for a light gray or brown color on the porcclain. If it is still white, open the pilot screws about the width of a dime and `take another ride. Continue doing this until the plugs have the nice light gray or brown color. Each pilot screw will be set a little differently since each cylinder is a little different. My pilot screws range from slightly less than 2 turns to about 2 1/4 turns. My bike runs great and I get about 41 mpg now. Good luck.

 

This might be a stupid question but have you adjusted the idle using the little knobby thing beneath the carbs?