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Discussion Starter #1
Well after I installed my new tank that was from a CB550 onto my CM400 it leaks gas out of the tube that comes from the bottom of the carbs. It just pours out even when it's running or if I close the petcock until the bowls are empty. It never did this before with the twist cap that was on the old tank. Now the new tank has the latching style cap on it if that makes any difference. Hell before I never even had to close my petcock after I turned it off and parked it. Now I do it ever time and it leaks until their empty. I was wondering if the tank is sealed more then before and it's become pressurized and pushing the fuel out or fuck I dunno. Can I just put rubber vacuum caps on the bottom of the bowls and close them up or no or maybe make a return line to have it feed back into the tank or maybe drill a hole into the top of the tank or lid to vent it like a motocross style gas cap? I'm running out of ideas and gas. I even tried just opening up the lid and seeing if that did anything but nothing. Maybe the seal is bad or something on the lid? HELP!!!
 

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The problem is in your carbs not the tank. I bet the 550 tank had some crud in it that is not letting the float needles seal against the seats. Pull the carbs and clean the rust from the 550 tank out of the float bowls and pull the needles and clean the seats. It will be ok. You might want to put some inline filters between the tank and the carbs.

Ken
 

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when was the last time you went through the carbs? i would agree that rust has ruined your day.
 

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This was a problem on my 350 recently.
Clean and/or rebuild the carbs.
Problem solved.
 

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Discussion Starter #6
I think the tank needed to be cleaned out as it's got some rust. Does the line from the petcock to the carbs need to keep aiming down? I just ask cause I didn't want it to act like a toilet cause from the petcock to the carbs, there's about three inches of room and the line is shaped like a macaroni noodle. I may have to have it loop around cause there isn't enough room between the petcock and carb to mount a filter.
 

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A new (longer) length of tubing will set you back about 30 cents...
 

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Discussion Starter #8
I didn't know if the tube always had to aim down towards the carbs is what I was asking. Being that if I mount a filter then it's gonna have a big loop or a hard bend? I'm not trying to make this harder then it seems.
 

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A bend in th eline doesn't mater since it is gravity feed. The float valve in the carb is what is supposed to keep it all from running out.

Ken
 

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Discussion Starter #10
Cool that's all I needed to know. I didn't know if the bends and whatnot would hamper the gravity fed flow. Thanks.
 

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I'm not sure what the hose routing and configuration of your bike is, but on the CB350, I used two inline filters that have an outlet at 90 degrees to the inlet, one in each line. It works perfectly.
 

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quote:Originally posted by CBRider

...I used two inline filters...
two filters isn't that overly redundant?
 

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Joe,
The cb350 runs two separate lines off the petcock, so 1 filter in each line.

Ken
 

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quote:Originally posted by kenessex

Joe,
The cb350 runs two separate lines off the petcock, so 1 filter in each line.

Ken
Ditto.
Works like a charm.
 
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