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Carb leak, Help!

sellsme

CB750 Member
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naples florida
I consider myself to be a fair mechanic, this one has got me stumped. I have a carb leaking from the over flow tube, float is set right, and checked, float and needle replaced. bench tested bowl for leaks, its good. Needle seat looks good with magnification. Is there any other way gas can get by the needle and seat? I hate when someone tells me that nothing is wrong but what's wrong? 1977 CB750K
 
Check the brass overflow tube in the float bowl, they tend to develop small hair line cracks which will allow a constant fuel leak no matter what you do. I fill the float bowl and put my finger on the bowl end of the overflow tube then use a little compressed air in the bottom where the rubber line usually goes. If it is cracked you will see bubbles.
 
I have bench tested the bowl, after one day it is still full of gas sitting on my bench and not leaking. The carb is clearly over filling. any other ideas? and thanks for your reply I will also try your method to check for leaks
 
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