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Hi,

There are two small hoses one the inboard side of the petcock, the front one hooks to the right hand carb and provides vacuum to operate the vacuum petcock. The rear hose is there to direct fuel to the bottom of the bike in case the diaphragm develops a leak.

See this thread at the old forum;

http://choppercharles.com/cs/forums/96728/ShowPost.aspx



edit;

After re-reading your question, I am not sure what fitting you are talking about. You may be seeing the float bowl vent??

There should be one on the other carb too.
 

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I'm glad that you figured out that he was refering to the petcock. My 81 had that and I made it work like the 80, no vacuum.
 

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Hi,

There are two small hoses one the inboard side of the petcock, the front one hooks to the right hand carb and provides vacuum to operate the vacuum petcock. The rear hose is there to direct fuel to the bottom of the bike in case the diaphragm develops a leak.

See this thread at the old forum;

http://choppercharles.com/cs/forums/96728/ShowPost.aspx



edit;

After re-reading your question, I am not sure what fitting you are talking about. You may be seeing the float bowl vent??

There should be one on the other carb too.
According to the first diagram animation, the open end of my "hose B" is sucking air. Is it supposed to do that?
 

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It shouldn't have vacuum, no. It is just a vent/drain If your other hose lines are correctly routed, your petcock diaphragm might be leaking, allowing vacuum from the right carb to bypass.
 

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Hello,



Have one open fitting on lefthand side bottom(towards inside of my 1982 cx500 carb....need a schematic

of the hose routing please..........



al


I believe you are talking about the carbs vacuum port (have an 82 and thats where mine is). As indicated in the posts above, that connects to the vacuum petcock and supplies vaccum pressure to the petcock diaphram. The other hose needs to be open for air to be drawn in and allow the diapham to move (thats why they show air going in). It basically makes sure that the diapham is open to the outside air so the carb vacuum can move it. The hose to the bottom of the bike is just there incase the diaphams ruptures as it would dump gas, better at the bike base than over the engine
 

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According to the first diagram animation, the open end of my "hose B" is sucking air. Is it supposed to do that?




YES. It actually doesnt suck air in like a vacuum cleaner, it just allows air to be taken in as the diaphram moves. If this did not happen (if the line was plugged) the diapham would not move as a vacuum would be developed when it tried to move via the carbs vacuum.
 

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YES. It actually doesnt suck air in like a vacuum cleaner, it just allows air to be taken in as the diaphram moves. If this did not happen (if the line was plugged) the diapham would not move as a vacuum would be developed when it tried to move via the carbs vacuum.


OK, I'll give you that, but it shouldn't be constant IMO. It would only draw in when the start up process was taking place so as to allow the petcock to open. If it was constant, there is a leak somewhere in the petcock allowing the vacuum from the carb to be present. The only allowable vacuum on that petcock B tube would be minute, and only for an instant, as the diaphragm moved to the open position.
 

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It can also act as a drain if one of the diaphragms fails.
 

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OK, I'll give you that, but it shouldn't be constant IMO. It would only draw in when the start up process was taking place so as to allow the petcock to open. If it was constant, there is a leak somewhere in the petcock allowing the vacuum from the carb to be present. The only allowable vacuum on that petcock B tube would be minute, and only for an instant, as the diaphragm moved to the open position.


Correct, doesnt suck in air so to speak as much as leave that side of the diaphram open to outside air pressure. When the carb vacuum pulls the diaphram, a pulse of air is drawn in, but just to compensate for the diaphrams movement. When the vacuum is removed, an equal amount of air will be expelled ( talking a air bubble the size of an M&M's)
 
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