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Running BUT not sucking gas from carbs

MotersickleBum

CB750 Enthusiast
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ok, i cleaned the carbs and i am able to get it running on starting fluid so i thought the hardest part was behind me. it will run but only on starting fluid even though i installed and filed the tank and gas is flowing to the carbs. i'm figuring that even if there is a vacuum leak, it should run but not very well. i had it tached-up to 2500rpm with starting fluid but can't keep it running. i pulled the carbs again and everything looks good. is it possible that these cheap plastic floats are bad and not allowing enough gas in the bowls?

but i got the tank painted anyway.

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Can you pull the bowls off and open petcock? Ummm, keep all floats closed, and open 1 at a time to see if you really do have gas flow. It really sounds like a gas cap issue to me


 
well yes, i could put it back together without the bowls but what i decided to do is to add gas to the carbs on my bench and then unscrew the drains and measure how much gas comes from each bowl. i had to stop because i ran out of light. will resume in the morning. this test will also tell me if a float is sticking open. but i was really dumbfounded that it wouldn't run when i put gas to it. i'm sure that it will though. this thing only has 4K miles on it. it just turned over 4k too. if i can get it running well it will be a fun, vintage bike to ride.
 
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