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Offline machacc

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Air bubble in gas line
« on: August 04, 2016, 10:14:55 AM »
My 78 550 always seems to have an air bubble in the gas line between the carb and the petcock.  It does occasionally spit and I was wondering if this could cause that.  I have not had the petcock off yet for a cleaning.  Ron
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Offline flybox1

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Re: Air bubble in gas line
« Reply #1 on: August 04, 2016, 10:17:36 AM »
No biggie, really. If your fuel line is routed well, they should all rise to the petcock, and eventually escape into the tank.
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Offline Duanob

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Re: Air bubble in gas line
« Reply #2 on: August 04, 2016, 11:15:27 AM »
It's all gravity fed, make sure there are no "up hills" in your fuel line routing. Also make sure the fuel line isn't too close to any hot spots on the motor as it might boil the gas before getting into the carb. I was having that issue but a reroute of the line fixed it. It's amazing how hot a bike can get when you sit in traffic.
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Offline machacc

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Re: Air bubble in gas line
« Reply #3 on: August 04, 2016, 03:04:14 PM »
Thanks for the suggestions.  It does bother me so I better fiddle with it until it's unworkable and then put a new line on it.  Ron
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Offline Gene

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Re: Air bubble in gas line
« Reply #4 on: August 04, 2016, 04:28:25 PM »
I usually have a little bubble on my 550 until I open the petcock . . . it's never been an issue.
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Offline Mantree

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Re: Air bubble in gas line
« Reply #5 on: August 04, 2016, 04:48:06 PM »
I replace my fule lines from time to time any way might as well just get a role of it and replace it while you reroute it
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Offline Steve F

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Re: Air bubble in gas line
« Reply #6 on: August 04, 2016, 06:24:02 PM »
I had opaque fuel lines and I never had an air bubble.... ;D
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Offline Mantree

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Re: Air bubble in gas line
« Reply #7 on: August 04, 2016, 06:45:32 PM »
Quote from: Steve F on August 04, 2016, 06:24:02 PM
I had opaque fuel lines and I never had an air bubble.... ;D
You should see what happens when you add a clear fuel filter

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Offline Don R

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Re: Air bubble in gas line
« Reply #8 on: August 06, 2016, 01:04:25 PM »
Quote from: Steve F on August 04, 2016, 06:24:02 PM
I had opaque fuel lines and I never had an air bubble.... ;D

 I replied that once and really PO'ed someone off. I agree, it doesn't seem to hurt anything, my brother has always ran his fuel lines down under the carbs through the filters and up into the carbs.  It flows just like the trap under your sink.
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Offline machacc

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Re: Air bubble in gas line
« Reply #9 on: August 06, 2016, 07:55:42 PM »
I shortened the tube by 1/2" and that may have solved the air bubble issue.  I'm pulling the carb off again for another cleaning and adjusting.  It's getting a valve adj. and timing recheck also.  Ron
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