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CB750 / Leaking Petcock and Carbs
« on: March 24, 2022, 12:42:19 PM »
CB750K4 1974.
Bike is running great but I noticed that the petcock was still delivering petrol even in the off position. It's only a drop every second or so but overnight it loses quite a lot. So I bought the gasket with the 4 holes in it and fitted it hoping that would solve the problem, but no it still leaks. I've tried everything but can't get it to seal 100% so assumed that this is probably normal. So the next problem is that one of the carbs loses this petrol through the overflow, so I thought I need to adjust the float level. Same as on my BMW R100 i.e bend the little tag slightly upwards to get it to shut the gas off a little earlier. However, I am either flooding the carb or it is dry. The very slightest of movement on the tag gives either too much fuel or none at all. I can't believe that it is so sensitive! I am moving it what seems like 10ths of a millimetre. and just can't get it right. Am I missing something? Could it be anything else? I have flushed the fuel inlet jet and confirmed that it does shut of fuel when the valve is put in the closed position. HELP please, I have been playing with this for 2 days now!
Bike is running great but I noticed that the petcock was still delivering petrol even in the off position. It's only a drop every second or so but overnight it loses quite a lot. So I bought the gasket with the 4 holes in it and fitted it hoping that would solve the problem, but no it still leaks. I've tried everything but can't get it to seal 100% so assumed that this is probably normal. So the next problem is that one of the carbs loses this petrol through the overflow, so I thought I need to adjust the float level. Same as on my BMW R100 i.e bend the little tag slightly upwards to get it to shut the gas off a little earlier. However, I am either flooding the carb or it is dry. The very slightest of movement on the tag gives either too much fuel or none at all. I can't believe that it is so sensitive! I am moving it what seems like 10ths of a millimetre. and just can't get it right. Am I missing something? Could it be anything else? I have flushed the fuel inlet jet and confirmed that it does shut of fuel when the valve is put in the closed position. HELP please, I have been playing with this for 2 days now!