more help needed on my carb problem

[Anonymous]

Hello
After resetting float height and performing Earl's test of blowing through fuel inlet hose with no air passing float needle, #3 carb is still dumping fuel.
It is now dumping as much fuel as it was before my carb rebuild. My fuel petcock is not working and allows fuel by in both the on and the reserve setting. Could the petcock malfunctioning overflow the float chamber with the float needles working properly? I know that they shouldn't be able to, but I am trying to look at all possiblities. My float height is now set at 27 mm as Earl suggested and when I had the carbs off to reset the float height, I adjusted my fuel mixture screws to 1 1/2 turns out.

Thanks Earl and everyone else for all help and input,
Billy Miles

PS: It only ran for no more than 10 minutes after the carbs were put back on and I looked for the fuel dumping. When I saw it I immediately took the carbs back off. Do you think any fuel in that time period got into the oil so that I would need to change it?

 

[earlfor]

Re: more help needed on my carb problem

With the engine running, you dont have to worry about fuel draining past the pistons and going into the crankcase oil. So no, you dont need to change the oil.

The petcock not working cannot overflow the float chambers if the float needles are working correctly and sealing as they should.

Have you replaced the "O" rings on the float needles with new ones?
(I am assuming the 550 has them just like my 750)

The petcock, you are going to have to replace or rebuild. Fuel running freely through it regardless of the selector setting will never do

I set my carb floats on the 750 to 25-26 mm. 27 may be a little low on the fuel level.

Is there any possibility that the fuel overflow tube on your #3 carb is broken off and the fuel in the bowl runs out the overflow prematurely?
Does the tube look to be the same length in all bowls?

Earl

Hello
After resetting float height and performing Earl's test of blowing through fuel inlet hose with no air passing float needle, #3 carb is still dumping fuel.
It is now dumping as much fuel as it was before my carb rebuild. My fuel petcock is not working and allows fuel by in both the on and the reserve setting. Could the petcock malfunctioning overflow the float chamber with the float needles working properly? I know that they shouldn't be able to, but I am trying to look at all possiblities. My float height is now set at 27 mm as Earl suggested and when I had the carbs off to reset the float height, I adjusted my fuel mixture screws to 1 1/2 turns out.

Thanks Earl and everyone else for all help and input,
Billy Miles

PS: It only ran for no more than 10 minutes after the carbs were put back on and I looked for the fuel dumping. When I saw it I immediately took the carbs back off. Do you think any fuel in that time period got into the oil so that I would need to chang


e it?

 

[Anonymous]

The "o"ring is just the little metal washer correct? If so they are all there, and new as of the rebuild last week. If I wanted to replace them just to be sure, how would I go about replacing just the "o" ring? Can I order it seperately, or can I get a similar washer of adequate type from a hardware store? I believe the overflow tubes are all the same length, but it will give me something to check in the morning.
I do truly appreciate all the help,
Thanks,
Billy Miles

If nothing else all of this work will make the ride that much sweeter, when it is all done.

 

[earlfor]

An "o" ring is like a rubber doughnut. On my 750, the float needle inserts into a housing. That housing can be unscrewed from the carb. Inside that housing at the bottom of the opening the float needle inserts into, can be seen a tiny "o" ring. The needle tip seals against it.
Some float needles are rubber tipped and dont require an "o" ring.
The problem here is that I dont know if the carbs on a 550 are exactly the same as those on a 750.

Earl

The "o"ring is just the little metal washer correct? If so they are all there, and new as of the rebuild last week. If I wanted to replace them just to be sure, how would I go about replacing just the "o" ring? Can I order it seperately, or can I get a similar washer of adequate type from a hardware store? I believe the overflow tubes are all the same length, but it will give me something to check in the morning.
I do truly appreciate all the help,
Thanks,
Billy Miles

If nothing else all of this work will make the ride that much sweeter, when it is all done.

 

[Anonymous]

On mine the needles just sit down in the housing. (no rubber doughnut). At least none of the needle assemblies had the "O"ring when I first took the carbs apart.

Would it cause a leak if the needle housing were over-tightened. If maybe the little washer was warped or something, even if I couldn't blow air past it?
Thank you for devoting so much time to those of us less knowledgable,
Billy

 

[earlfor]

Thats the part that is really a puzzle to me. If air cannot flow past the needle, then how is it that fuel can flow past?

Are you sure there is no fluid inside your floats and that they do in fact float?

What did you use to base your measurement for the height on?
Did you use the bare metal surface that the gask would sit on, but minus the gasket? Is your measurement to the top of the float when the carb is held upside down? Just for the heck of it, try placing your float needles in different carbs and see if they seat any better.

Earl

Would it cause a leak if the needle housing were over-tightened. If maybe the little washer was warped or something, even if I couldn't blow air past it?

 

[SqDancerLynn1]

do you have the older Slide type carbs Think so? The seat assembly screws into the carb body NO O ring, just the washer If you replaced the needle and the seat assembly when they were rebuilt I would suspect the float. I would also change the needle/seat assembly with one from one of the other carbs. If the other carb then starts to leak the needle/seat assembly is bad.