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Post by martinackermann on Jul 22, 2023 2:34:09 GMT -5
Hi all I would like to know if the pipe that goes from the fuel tap to the front of the carb air intake that operates the diaphragm should have a small constant amount of air you can suck through the pipe? My diaphragm is fairly new and I can not see any holes in the rubber, I’m looking at the thing and thinking that only the amount of air that the diaphragm displaces should be able to be sucked through the pipe, and anything else could be a small amount of YB governed fuel going into the carb, then there is a airway on the plastic plate between the two rubber squares, but that’s on the other side, and I’m thinking it’s only there for the operation of the diaphragm to work properly. I would really appreciate some help, thanks. Martin
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Post by G Man on Jul 22, 2023 7:54:55 GMT -5
You can only pull, or draw, the slightest amount of "air" through the line. Take care not to draw on it too hard as the diaphragm can be damaged.
During operation, the intake vacuum in the manifold causes a negative vacuum pull within the hose to the fuel tap which makes a light pull on the diaphragm. The diaphragm holds the valve open in the tap and allows fuel to flow through the tap. When the intake vacuum stops, ie: motor off, the diaphragm relaxes back and closes the valve in the fuel tap.
Is this what you are asking?
G Man
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Post by martinackermann on Jul 30, 2023 14:57:19 GMT -5
You can only pull, or draw, the slightest amount of "air" through the line. Take care not to draw on it too hard as the diaphragm can be damaged. During operation, the intake vacuum in the manifold causes a negative vacuum pull within the hose to the fuel tap which makes a light pull on the diaphragm. The diaphragm holds the valve open in the tap and allows fuel to flow through the tap. When the intake vacuum stops, ie: motor off, the diaphragm relaxes back and closes the valve in the fuel tap. Is this what you are asking? G Man |
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Post by martinackermann on Jul 30, 2023 15:29:39 GMT -5
Hello Gman thank you for forwarding that to me, I was wondering about a minimal constant flow of air. With my finger, i blocked the small passage way thats in the square piece of plastic between the two rubbers that make up the diaphram, and the small constant amount of air stopped, my diaphram is fairly new though, so maybe i should move on... im trying to eliminate one thing at a time as im getting fluctuating revs on 1/4 throttle, and itd driving me a little crazy now. it seems to be running pretty rich. I will have the carb off again tomorrow and check the choke cut off rubber has not deteriorated, i have checked the float level ,and i had my stator fully rewound recently and all the ignition components are within thair values... unlikely i would say but i will plug in my 2 spare pulsers tomorrow to try and eliminate that too. So im really wondering what else it could be. i have so many nicer things to be doing to my bike. Any ideas would be very much apreciated as i would really like to have it running good again. martin
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Post by gcrank1 on Aug 4, 2023 21:06:51 GMT -5
Turn petcock to Prime to test the running, that is direct flow not dependent upon the vac function.
Note:
When you pull the vac line off the petcock look for any gas in that line and lower it to see if any runs out. If there is gas there the diaphragm is leaking thus allowing gas to be sucked into the carb and messing with the jetting. Really Hard to tune the carb if that is happening; btdt! Gave me FITS until I found it.
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