Fuel Problem

[ldjr81]

I just replaced the stock vaccum petcock on my 81 XS650 with a non-vaccum type from mike's xs. The fuel will flow fine with the fuel line disconected from the carbs, but as soon as I hook it to the carbs it will not flow. I'm a little stumped on this one so any info would be appreciated.
Thanks

 

[littlebill31]

Are your float bowls filling? If the float valve is stuck, fuel will not enter the bowls.
Or, if the bowls are full of fuel no more will go into them unless the engine is running, using the fuel.

 

[sreimer]

I'm guessing that was a "DUH"

 

[ldjr81]

Fuel isn't even reaching the carbs. I have clear fuel line on it and like I said unhooked from the carb fuel flows fine out of the fuel line, turn the petcock off hook the line back to the carb then I get nothing. On position or reserve nothing flows. Doesn't make sense to me.

 

[weekendrider]

You've opened the bowl drain and nothing comes out?

 

[littlebill31]

As weekendrider says, check the float bowl. There is a screw on the bottomand a nipple. Turn the screw out and see if fuel comes out. Put a piece of fuel line on the drain nipple to prevent the fuel from going everywhere.
This might be a stupid question, but have you started the bike?
The float valve is what let's fuel in. If the floats, or valve, are stuck no fuel will go into them.
Did you rebuild the carbs?
www.amckayltd.com/carbguide.pdf

 

[sreimer]

Pull the drain plugs out of the bottom of the carbs if still nothing tap the float bowls with a screwdriver handle (while the drain plugs are out )

 

[ldjr81]

Yeah I had the carbs rebuilt. The bike ran before but not right, so I had the carbs ultrasonic clean and professionaly rebuilt and replaced the vaccum petcock with a non vaccum type. Now the only way it'll run is if I spray carb cleaner in the carbs. It just seems I'm not getting fuel from the tank while its hooked up.

 

[timbeck]

Cap vent?????

 

[littlebill31]

They need to be taken apart again, plain and simple. The floats and float valve are the first pieces that regulate fuel flow. These can become stuck very easily. Fuel sitting in the bowls for only a couple months can gum them up

 

[ldjr81]

Alright I'll give that a try.

 

[ldjr81]

Well I took the bowls off and the float and float valve seem to be ok. I have fuel in the bowls, but the main jets seem to be plug up with gunk. Also what is the purpose of the rubber plug that seals the pilot jet? They were replaced once and both times they seem to gum up and fall apart. Is there a better way this should be done or is it not needed at all? Thanks

 

[gggGary]

Gotta have the pilot jet plugs, bike won't run with out them. Has the fuel tank been cleaned, sealed?

Note the fuel level inside the screen in this pic.



Doesn't take much to stop gas flow unless you WANT it to stop

 

[littlebill31]

Your pilot circuit controls idle to about 1/4 throttle. These carbs work on throttle position, not engine speed. If the bike is not starting on it's own then the pilot circuit, which includes the enricher/choke, is clogged.
Also, if the rubber plug is "melting" then you have some bad fuel issues. E-10 fuel is terrible on rubber parts. Letting fuel sit in a bowl will cause it to varnish, then (because E-10 is also a cleaner) once the fresher fuel comes into contact with it, it will cause the varnish to flake off and clog shit up. A piece the size of a tiny pin head can render the carbs inoperable.
Those carbs need to be stripped down and cleaned 100%. Not just spraying some cleaner across the throats, but freaking cleaned!!!

 

[ldjr81]

Sounds like a plan. I had the carbs sonic cleaned and was not impressed by the results. I've had better results soaking carbs in a gallon pail of carb cleaner. And there is not doubt this E10 fuel sucks I've heard a lot of small engine guys saying how bad it is for small engines. Is there anything that can be added to the fuel (that actually works) to improve the quality of the fuel? Thanks a lot guys for the info so I guess now I got to get to work. Thanks again

 

[gggGary]

We have had e10 for years now the only time it is an issue is when some machine has been dragged out of hibernation to be reborn the alcohol is a solvent and dissolves all the old varnish in the carbs AND think about about how much is built up in the GAS TANK! Once the varnish is gone and the ancient rubber has been replaced the ethanol keeps a nice clean fuel system. I have had my 83 for three years now after the first complete cleaning and overhaul I get it out in the spring start it up and drive away. No plugged up jets and stuck floats like in the old days.

 

[littlebill31]

Yes, that's what I was trying to mean, lol. The mixing of fuels can cause havoc in engines. Little sluffed pieces getting stuck in stuff. I will also ad that some preservatives can junk shit up as well.
Using an old gas tank, or dirty carbs, with new, fresh fuel can clo it up good.

 

[ldjr81]

Alright well the tank doesn't look too hateful but I'm sure with 30 yrs of crud it could use a good cleaning. Any products or techniques you guys would recomend?

 

[gggGary]

put e10 or )just an idea) some e85 in and shake it up, sit shake a few times, dump it out repeat. catch the gas strain it and use it up in your lawn mower. I mix old skunk gas about 30% in my lawn mower to get rid of it.