Topic: Does it matter which fuel line goes to which carb?

[paulages]

i should point out that the inline filters can cause bad flow problems even if the petcock is perfectly clean and flowing from both nipples. mine sometimes get air trapped below the filter, which seems to have a hard time travelling back up through the filter and into the tank. i just flushed my tank out again recently and completely rebuilt my petcock (new screen/tube assembly and thorough cleaning of the lower body), and i am still having flow problems every once in a while. when it happens to me, my bike suddenly runs exactly as you describe: it seems like it's running out of gas to two of the cylinders.

when this happens (usually when i sputter in between running out of gas and switching to my reserve), i can squeeze on the fuel line going to 3 and 4, and actually force the air back through the filter. amazingly, sometimes it will run fine when it looks like there is no fuel at all travelling through this air pocket (it must be trickling very lightly), but i have to believe that this will affect high RPM fuel needs.

in any case, inline filters suck and are extremely problematic. it helps to make sure that they run "downhill" the entire way to your carbs, helping to eliminate air pockets.

but i think you have dirty pilots anyway...

[paulages]

BTW: there is a metal cleaning service up on vancouver way (near western mc salvage) who will chemically strip your tank inside and out for $45. comes out completely bare, like new.......bye bye rust.

[78_SaltLick]

i should point out that the inline filters can cause bad flow problems even if the petcock is perfectly clean and flowing from both nipples. mine sometimes get air trapped below the filter, which seems to have a hard time travelling back up through the filter and into the tank. i just flushed my tank out again recently and completely rebuilt my petcock (new screen/tube assembly and thorough cleaning of the lower body), and i am still having flow problems every once in a while. when it happens to me, my bike suddenly runs exactly as you describe: it seems like it's running out of gas to two of the cylinders.

when this happens (usually when i sputter in between running out of gas and switching to my reserve), i can squeeze on the fuel line going to 3 and 4, and actually force the air back through the filter. amazingly, sometimes it will run fine when it looks like there is no fuel at all travelling through this air pocket (it must be trickling very lightly), but i have to believe that this will affect high RPM fuel needs.

in any case, inline filters suck and are extremely problematic. it helps to make sure that they run "downhill" the entire way to your carbs, helping to eliminate air pockets.

but i think you have dirty pilots anyway...

man, like i said before i had noticed "bubbles" of air flowing from one fuel line towards the carbs, and this like you said is flowing "uphill" towards the carbs.....hmm i replaced the inline fuel filters yesterday...sucky thing is all they had was straight filters meaning there was no 90 degree bend on either end, so its been hard trying to run the line straight or at a curve that does not pinch the tube. Now that i think about it everytime i drained the float bowls when my bike ran like #$%* i also tapped the fuel lines with my finger a few times, maybe its not emptying out the float bowls but tapping the fuel lines that is getting rid of the bubbles that is curing the issue. Either way, next step is to clean out the slow jets, if this does nothing i will try to reroute the fuel lines so its going downhill.

[techy5025]

I think the slow jets are your problem....and don't assume that just because you
can see a tiny ray of liight through them they are clean. After screwing with mine
for two days, I replaced them and all is now well.  I have never used inline filters,
but then again my tank has been almost free of any rust.  It just seems like one
additional worry bead. 

My diecast has always been clean. The sandcast has a set of carbs of dubious
history and had the slow jet problem.

Jim

[cbjunkie]

how are your tubes run? and...to do you the honor of NOT assuming anything - did you put the filters in the right way? - there should be an arrow on them...

here's a scanned diagram of how mine are run...
i have a short (2") piece of tubing from the petcock, then the filter, then the tubes run down and under the carbs. the connector tubes of the carbs are pointed DOWN and the rubber fuel line goes UP into them

[78_SaltLick]

how are your tubes run? and...to do you the honor of NOT assuming anything - did you put the filters in the right way? - there should be an arrow on them...

here's a scanned diagram of how mine are run...
i have a short (2") piece of tubing from the petcock, then the filter, then the tubes run down and under the carbs. the connector tubes of the carbs are pointed DOWN and the rubber fuel line goes UP into them

i have the arrow on the filters pointing towards the carbs, and one of my fuel lines runs downhill the other one runs uphill because....well because....well shoot ill have to go home and look......

[cbjunkie]

i have run them this way because it provides a virtually kink-free path...

[paulages]

cbj-- it's a little harder on the 550's to have enough room to fit the filters right underneath the petcock. one of mine sits just under it (with a 90 deg. filter), like yours does, but the other just won't fit there. there is very little clearance between the petcock and the #1 intake manifold. i have it sitting right between carbs 2 and 3, where there is a little hook for holding the fuel line in place. it runs all downhill when the bike is sitting up straight.

best scenario: have the tank completely rust free, and screw the filters.

[78_SaltLick]

Sigh, i just looked in my tank and although it seemed rust free the first time i cleaned it a few days ago, i took a better look with a pen flashlight and can see half ways towards the back is still pretty rusted, going up the tank all the way around about 2 inches high, crap i probably just loosened up the rust enough there now to really get some chunks up in the carbs.....good lord that was alot of work the first time to drain the gas and try to clean it out....paulages im leaning towards taking the tank down to that place you mentioned, when they clean the tank you said inside and out right? Does that mean the paint will be gone as well on the outside? Do they boil it or something? Its stupid for me to blow the slow jets out and put new inline fuel filters if i dont clean out the tank right the first time....the POR 15 treatment costs about the same as what you said paulages for that place to do it......that way i can say screw the inline filters......by the way how the hell do you guys get the float bowls off #2 and #3? i can get one and 4 off no problem, pulled the slow jets off that and the main jet and cleaned those out....but there must be a special tool used to get to those screws, only way i can see is to pull the carbs off.....

[78_SaltLick]

BTW: there is a metal cleaning service up on vancouver way (near western mc salvage) who will chemically strip your tank inside and out for $45. comes out completely bare, like new.......bye bye rust.

paulages you ever been to that MC salvage yard in Tigard? I once got a 1974 cb750 sunrise metalflake orange tank w/petcock for $10. Inside needed alot of help, but the outside was in good shape. They dont have alot of parts but have a load of seats and tanks off CB's for sale for cheap.

[paulages]

yeah, actually i bought my cb550F "parts bike" off of troy. not the shop but him personally. that's now the one i ride everyday.

yes, they chemically boil it. it is bare inside and out. gotta sort out a paint job, but you certainly won't have any rust. also, mac's radiator shop on se foster rd. has a snadblasting attachment that will go inside your tank. they'll blast it, boil it, and coat the inside (looks a lot like red-kote to me) for around a hundred and a quarter. you might try asking them if they'll just blast the inside without damaging the paint. if so, let me know...

[BigDogNZ]

BTW: there is a metal cleaning service up on vancouver way (near western mc salvage) who will chemically strip your tank inside and out for $45. comes out completely bare, like new.......bye bye rust.

paulages you ever been to that MC salvage yard in Tigard? I once got a 1974 cb750 sunrise metalflake orange tank w/petcock for $10. Inside needed alot of help, but the outside was in good shape. They dont have alot of parts but have a load of seats and tanks off CB's for sale for cheap.

They got a good tank and seat for k1 cb500f???  Put me in touch.... pleeeeease....

[rabidelf]

When I bought my old 500 recently I was immediately in motion to buy new carb rebuild kits, new gaskets and diaphram for the petcock, kreem tank lining kit and new fuel lines. I ripped it all apart, scoured and cleaned for hours rebuilt it and put it all back together. Now there is no question: if it don't run right, it ain't a fuel problem. Like Ripley said "Take off and nuke it from orbit. Only way to be sure"  P.S. It started right up.

[78_SaltLick]

Great,

while trying to get the slow jet out of #2 carb it broke off with the threads inside. Man this sucks, i dont mind fixing a few things but jesus christ ive got a shopping list going at this point of #$%* ive fixed with no results, now this.....

[paulages]

welcome to owning a 30 year old machine...

[78_SaltLick]

welcome to owning a 30 year old machine...

sweet..