Greasy buildup on outside of carb

[jamesarr]

Can anyone tell me what might be causing this buildup on the outside of my right carb. Not having the issue on the left side.

 

[ancientdad]

Moved to Smaller Twins Carburetion and Fuel section.

It looks like a long term buildup of fuel vapors from the little bowl vent on the side of the carb body just above and to the left of the idle stop screw

 

[suhawk305]

Moved to Smaller Twins Carburetion and Fuel section.

It looks like a long term buildup of fuel vapors from the little bowl vent on the side of the carb body just above and to the left of the idle stop screw

View attachment 11755

I agree with ancientdad’s assessment. My CB77 carbs looked like that before I cleaned and rebuilt them.

 

[jamesarr]

Thank you both! Is there any thing I need to do besides clean it up? I'm thinking my petcock might be leaking. Would that increase/speed up the buildup from the vent?

 

[ancientdad]

Thank you both! Is there any thing I need to do besides clean it up? I'm thinking my petcock might be leaking. Would that increase/speed up the buildup from the vent?

If the petcock is leaking this also means the float level might be a bit high in that carb, or the float needle may not be sealing as well. Vapors out of the vent would take quite a while to build up that much evaporated fuel to make that film. I'm sure you're aware that on all these old twins, when you shut off the engine you should also turn off the petcock (given that it doesn't leak when turned off). Yes, clean it up but check those other possibilities too

 

[jamesarr]

Thanks again! I'm pretty good about turning the petcock off each time. Also, I have a new petcock i can install and see if that fixes it this issue.

 

[ancientdad]

Thanks again! I'm pretty good about turning the petcock off each time. Also, I have a new petcock i can install and see if that fixes it this issue.

Some carb spray will wash off most, if not all, of that gunk. Try to cover the little vent hole when you spray it on the carb body, you don't want it to get into the float bowl as it will swell any rubber parts

 

[jamesarr]

Thanks!

 

[66Sprint]

Thanks again! I'm pretty good about turning the petcock off each time. Also, I have a new petcock i can install and see if that fixes it this issue.

Change the oil if it smells AT ALL of fuel....."pretty good" is not enough......EVERY TIME is the requirement.......

 

[jamesarr]

Thanks for tip about the oil!