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Discussion Starter #1
Hello all, iv been slowly but surely getting my 72 cb350 road worthy. One of the last things (hopefully) I need to do is to fix the carburetors. I was told It could be a sticking float that are causing the gas leak, when the petcock is left on. I was also told my needle valve might need replacing. Is there anyway to know exactly what carburetor I should take off to check left side or right? Also I'm assuming if I take the carbs off to check/ rebuild them they will need to be re-adjusted? Thanks -Eli
 

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Assuming the gas is coming out the overflow, it should be evident which carb is causing the problem. If you disconnect the air cleaner, gas line, and choke linkage between the two carbs, you can loosen the intake clamp and pull the carb out enough to work on it without disconnecting the throttle cable. If you don’t mess with the idle mixture screw or the idle speed screw, the carbs should stay synchronized.

As for the cause of the leak, you could have: stuck float, float with a pinhole in it (gas in the float causing it to not float), trash in the float valve keeping it from closing, worn out float valve, float level way out of adjustment, or a crack in the brass overflow tube in the float bowl.
 

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Discussion Starter #3
Alright thanks for the input, its unfortunately not leaking out either overflow, which I'm a little puzzled about. It dies after 5 minutes of idleing so I'm gonna start with the ignition timing make sure that's not causing it. Then I'll pull apart the carbs. -Eli
 

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If it's not leaking out the overflow where is it leaking from? Leaking while the engine's running or when it's shut off? If it's not running the petcock needs to be shut off.
 

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Alright thanks for the input, its unfortunately not leaking out either overflow, which I'm a little puzzled about. It dies after 5 minutes of idleing so I'm gonna start with the ignition timing make sure that's not causing it. Then I'll pull apart the carbs. -Eli
Then, why do you think it’s leaking?
 

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Discussion Starter #6
Alrighty update, so its leaking from the carb over flows (both) when the bike is not running and the petcock is left on. Not sure if this is just an error on my part or if you should be able to leave the petcock on without it overflowing. Thanks -Eli
 

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It’s always a good idea to turn your petcock off when you park the bike, but no, they shouldn’t overflow when the petcock is on. If both carbs are overflowing, my guess is there’s a lot of rust or trash in your gas and it’s keeping the float valves from closing all the way.
 

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Discussion Starter #8
Yeah the gas is a darkish gross yellow when it leaks. I'm gonna take the tank off, drain the gas, clean the tank. And I guess rebuild the carbs?
 

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Just clean the carbs. If it has been running ok, there’s no need for a rebuild.
 
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