Author Topic: whats the trick? (Read 4508 times)

famoussas1 · « **on:** February 28, 2010, 11:23:26 AM »

ok, so got everything back together on my 74 550. filled up the gas tank, and got a nice air bubble in my new clear gas line from the petcock to the carbs. no biggie, little flow but bubble. turns right over, runs for a few sec. then quits, seems like theres no flow now, drained some gas from each carb bowl, and the bubble looks like its gonna drop into the carbs, but when i stop draining the bubble rises up back to the fuel line, like its formed its own little vacuum. any little trick here to relieve this bubble?

754 · « **Reply #1 on:** February 28, 2010, 12:07:07 PM »

Dont worry about the bubble, just worry about fuel into the carbs..

BobbyR · « **Reply #2 on:** February 28, 2010, 12:18:36 PM »

You will need to re route your gas line to eliminate to bubble. The rule of thumb is you need that fuel always moving downhill. Dips in the line can trap air.

TwoTired · « **Reply #3 on:** February 28, 2010, 12:27:42 PM »

Fuel system is gravity fed, not mechanically pressurized. If you have a bubble it is because of improper fuel line routing from fuel tap to carb inlet preventing the bubble from reaching the fuel tank.

The bubble will impede flow at a rate related to the fuel level in the tank. Higher fuel levels are less effected by the bubble. Most significant in gravity fed systems is the difference in fuel level in the tank related to the inlets (float valves) of the carbs.

Unless there is a constant and steady "fall" in the line between fuel tap and carb, there will always be a bubble in the line fighting fuel flow, as there is an air source in the carb at the float valve that will feed it to the line when the float valve is opened.

Don R · « **Reply #4 on:** February 28, 2010, 02:14:04 PM »

If you use black fuel line the bubble won't be a problem. Seriously though, I run mine down then up, the bubble empties into the carb bowl and is replaced with fuel. No worries.

famoussas1 · « **Reply #5 on:** February 28, 2010, 03:42:50 PM »

how is there a difference between black or clear fuel line? the tank only has about 2 gallons of fuel. if theres air in the tank will that hurt me as opposed to the whole inner tank filter being submerged in gas?

the line goes directly from the petcock, downward to the fuel inlet on the carbs, no rise or even level line on the path of travel.

TwoTired · « **Reply #6 on:** February 28, 2010, 04:03:40 PM »

Quote from: famoussas1 on February 28, 2010, 03:42:50 PM

the line goes directly from the petcock, downward to the fuel inlet on the carbs, no rise or even level line on the path of travel.

Bubbles always rise to the surface in liquids, as they are more bouyant. How can the line hold a bubble if routed in a descention arrangement?
Is your bike on the side stand?

Bodi · « **Reply #7 on:** February 28, 2010, 04:16:39 PM »

The difference is that you won't see the bubble and assume it's a problem. It is not.

BobbyR · « **Reply #8 on:** February 28, 2010, 04:19:07 PM »

Let me try to smooth this out for you. The fuel line should be routed as straight and at as steep a downward angle as possible from the petcock to the fuel inlet. If you do that the line will remain full of fuel until the tank runs dry. TT is correct if you route the fuel line properly any bubbles will rise up the line to the tank and disappear. Color has to effect.

Frostyboy · « **Reply #9 on:** February 28, 2010, 05:39:58 PM »

Quote from: Don R on February 28, 2010, 02:14:04 PM

If you use black fuel line the bubble won't be a problem.

roflmao

I think the humor there has been missed Don.
I've never been keen to use clear hose for fuel delivery on anything. All clear stuff I've encountered, even if specified for petrol, always seems to go rock hard.

famoussas1 · « **Reply #10 on:** February 28, 2010, 06:37:11 PM »

well i dont know...the line is going downward, and its just not flowin. not sure if a tank with only 1 gallon is my prob...doubt it but even bike centered and opening petcock is not flowing for anything. maybe my clear line is the prob.

754 · « **Reply #11 on:** February 28, 2010, 06:46:59 PM »

What we are saying is a bubble is not necessarily your problem,,with black you wont notice it.. with clear it drives you nuts (& may not matter.

I used to run braided line with an inline clear CR filter,, the bubble at first drove me nuts... until I realized that you can & probably will have bubbles..AND flow fuel...

Patrick · « **Reply #12 on:** February 28, 2010, 06:54:34 PM »

Does the 550 have the petcock screen inside the tank? If so, did you remove the petcock and make sure the screen was clear, allowing free fuel flow into the fuel lines?

Just a thought....

Patrick

famoussas1 · « **Reply #13 on:** February 28, 2010, 07:44:49 PM »

i understood the black line and outta sight outta mind idea...this thing is just frustrating me. i only have a 1 gallon gas can, so ive filled it twice, making sure theres enough gas in the tank to push the bubble out or whatever. got a few gallons in the tank, just flowing slow, not a bubble more restricted flow. when i open the bowl if flows fine...seems like theres a small vacuum of air just hoovering in the line. ill add more gas to the tank and check the filter as well, should be ok as i vinegared the tank and rinsed it out well, should be cleaner than it was last fall when it last ran.

and i pulled a plug, nice blue spark present...so it must be a fuel flow issue. i think im smarter than the bike..ill get it eventually.

754 · « **Reply #14 on:** February 28, 2010, 08:01:06 PM »

stop worrying about the bubble, check fuel flow, and stop trying to get the bubble out..

mlinder · « **Reply #15 on:** February 28, 2010, 10:23:13 PM »

1 gallon is pretty much reserve on these. If all you have is one gallon, you'd better be on reserve if you want to get gas out of the tank and into your carbs.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #16 on:** February 28, 2010, 11:00:57 PM »

Check your gas cap vent

BLUE71TURBO · « **Reply #17 on:** February 28, 2010, 11:29:08 PM »

Quote from: Jerry Rxman Griffin on February 28, 2010, 11:00:57 PM

Check your gas cap vent

X 100 !

ekpent · « **Reply #18 on:** March 01, 2010, 06:21:13 AM »

Probably not, but does vinegar,like he used to wash his tank have any effect on aluminium. Sounds like he kept his petcock mounted during cleaning-bad idea. If you did that with "The Works" you would ruin it and maybe make a bomb.

754 · « **Reply #19 on:** March 01, 2010, 07:28:35 AM »

When diagnosing fuel problems, always put it on reserve..

Don R · « **Reply #20 on:** March 01, 2010, 08:17:08 AM »

You might need to clean the inside of the petcock. Mine was plugged with sediment and gunk. Remove the hose and open the petcock letting the fuel flow into a container so you can observe the flow.

flybox1 · « **Reply #21 on:** March 01, 2010, 08:20:17 AM »

Quote from: 754 on February 28, 2010, 08:01:06 PM

stop worrying about the bubble, check fuel flow, and stop trying to get the bubble out..

+1

tank vapor locked / clogged petcock.
Don R beat me to it.
take off your fuel line and open 'er up. how does she pee?

mlinder · « **Reply #22 on:** March 01, 2010, 09:45:18 AM »

1 gallon.

Reserve.

famoussas1 · « **Reply #23 on:** March 01, 2010, 03:51:57 PM »

thanks for all the input. ok, got 3 gallons of fresh 87 in there, and a new petcock with new filter screen in tank. when i pull the fuel line off she pees nicely. tiny flow when i attach line to carbs. got her to kick over, a rough idle for about 5 sec. but then died, cant keep her running. got spark, fuel is my question so thats where i am at now. ran the battery down so its charging again. grr.

BobbyR · « **Reply #24 on:** March 01, 2010, 07:33:58 PM »

Quote from: famoussas1 on March 01, 2010, 03:51:57 PM

thanks for all the input. ok, got 3 gallons of fresh 87 in there, and a new petcock with new filter screen in tank. when i pull the fuel line off she pees nicely. tiny flow when i attach line to carbs. got her to kick over, a rough idle for about 5 sec. but then died, cant keep her running. got spark, fuel is my question so thats where i am at now. ran the battery down so its charging again. grr.

I did not see where you have pulled the carbs and given them a good cleaning, you may have done that so I apologize in advance. This sounds like classic dirty carb behavior. Also check your float level. There are a lot if threads on carb cleaning, I would do a search.

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Author Topic: whats the trick? (Read 4508 times)