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Discussion Starter #1
Hey all. I

Forgive me if this has been covered but I'm at a loss and can't find any ideas.

I did a complete rebuild/cleaning of my carbs.

Checked the floats and needles. All good. Adjusted float heights to manual spec. All good.

Brand new gaskets. All good.

Put the carbs back onto the bike and opened up the petcock to refill the carbs and an ocean of gasoline came pouring out the bottom of my baby.

Took the carbs back off. Retightened the bowls. Cleaned the carbs off. Tested by pouring gas into the gas tube. Poured plenty that it should have leaked again if it wasn't fixed.

No leaks! Yay..
Uh I may have spoke to soon.

As I thought the problem was solved I put the bike back together and filled bowls back up. To my great dismay the no. 2 + 3 bowls where leaning again.

Seems like it's coming directly from the gasket. They are brand new! WTF! I'm completely at a loss.
 

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Leaky

Even if the gasket leaked, it should not leak with the bike sitting still and upright. The needle valve should shut the fuel off before it reaches the gasket. I think the needle valve or the seat is faulty, or it is not adjusted correctly.

Unkle Crusty*
 

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Ace Tuner
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Gasoline has a very low viscosity (thin) and will easily flow around and down corners and such.
Probably the 'o' rings on the fuel "T" inlet in between #2 and #3 carbs are leaking and fuel is running down around the edges of the float bowls.
To verify you will need to remove the carburetors yet again.

Make sure they are clean and dry.
Then use a remote tank (your fuel tank will do) suspended above the carb's and watch for the very first sign of fuel leakage.
Pay close attention to the fuel "T" and the other fuel pipes that supply #1 and #4 while you're at it.

Unfortunately it's a fairly big job to replace the fuel pipe 'o' rings because you have to split the carb assemblies to get to them.
If it does turn out to be the o rings on the "T" fuel inlet, I would replace the ones for #1 and #4 while it's apart.

Hope this helps, let us know what you find.
 

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Discussion Starter #4
Semi - the not sure what you mean by T- inlet. There is only one pipe at the bottom of the carb assembly that fills the bowls. Not at the top. So if I'm understanding you at all, I don't know if that would be an issue. Please correct me if I'm not understanding. But I will certainly retest with your suggestion and take video from multiple angles. The carbs weren't leaking before I disassembled them. Not sure if that is relevant.

Crusty: this is what I'm hoping. I did adjust the float heights and I'm thinking I misadjusted to make the bike run a bit richer. It was running out of power at high speeds and not as responsive as it should be at initial throttle.

I won't have access to my garage until Wednesday. I'll let you guys know.
 

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Tom, the float bowls must be inverted. I had this same prob with an old honda 750, I had mistaken the bowl seat(which is slightly indented and inset into the carb body) with the casting marks which are ridges around the bowl area. Who would think that they would make a carb float bowl that could go on backwards huh?!!? You also could have a drain screw o-ring going bad. If the carb bodies have drain pipes on them, the screws may be stripped, so check for cracked drains, bad screws, and also for fuel tank leaks around the petcocks that might drain down to the carbs.
(and don't laugh at monsters)
 

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T up.

I think the T Semi is referring to is between the carbs. Assuming you have 4 carbs and two fuel lines. That would require a T in each line between 1 and 2, and between 3 and 4. That is how it is my my XS11 and XS1100.
My XS400 also has 1 fuel line feeding two carbs, so it has a connection pipe between the two.
If it is leaking there, it should be noticeable, especially with the filter off.

Unkle Crusty*
 

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Semi - the not sure what you mean by T- inlet. There is only one pipe at the bottom of the carb assembly that fills the bowls. Not at the top. So if I'm understanding you at all, I don't know if that would be an issue. Please correct me if I'm not understanding. But I will certainly retest with your suggestion and take video from multiple angles. The carbs weren't leaking before I disassembled them. Not sure if that is relevant.

Crusty: this is what I'm hoping. I did adjust the float heights and I'm thinking I misadjusted to make the bike run a bit richer. It was running out of power at high speeds and not as responsive as it should be at initial throttle.

I won't have access to my garage until Wednesday. I'll let you guys know.
The 'T' fuel inlet I was referring to is:

If I'm looking at the correct parts diagram, you have one fuel hose coming from the fuel tank going down to the carburetors.
The place that fuel hose connects to the carb's is the 'T' that sits in between the #2 and #3 carb's.
It is down at the bottom very close to the fuel bowls for the #2 and #3 carb's. I've had them leak before.
When it leaks there, it looks like fuel is coming from the fuel bowls because fuel runs around the edges of the bowl gasket area.

Just handling the carburetors can cause the 'o' rings on that 'T' to leak.

May not be what's happening, but it's the first thing I thought of when you said new gaskets and both #2 and #3 are leaking.
 

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Discussion Starter #8
The 'T' fuel inlet I was referring to is:



If I'm looking at the correct parts diagram, you have one fuel hose coming from the fuel tank going down to the carburetors.

The place that fuel hose connects to the carb's is the 'T' that sits in between the #2 and #3 carb's.

It is down at the bottom very close to the fuel bowls for the #2 and #3 carb's. I've had them leak before.

When it leaks there, it looks like fuel is coming from the fuel bowls because fuel runs around the edges of the bowl gasket area.



Just handling the carburetors can cause the 'o' rings on that 'T' to leak.



May not be what's happening, but it's the first thing I thought of when you said new gaskets and both #2 and #3 are leaking.

I took slow motion closeup video of the area. Seems that you are right. Now what?!!!!ugh the weather has been in the mid sixties. This is so depressing not being able to ride
 

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You have to split the carburetors to replace the 'o' rings on the T fitting.
While you're at it and you have it apart you should replace the 'o' rings on the fuel pipes that supply fuel to the #1 and #4 carbs also.
Soon as you don't they will leak, then back apart............
STUDY the way the springs at/near the sync adjusters are arranged before you take it apart. Some close up pics may be helpful for reassembly.
Just go slow, watch closely as you remove parts.
You will have to re-set the carb sync after it's back together.

Good luck,
SemiFast
 

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Discussion Starter #10
You have to split the carburetors to replace the 'o' rings on the T fitting.

While you're at it and you have it apart you should replace the 'o' rings on the fuel pipes that supply fuel to the #1 and #4 carbs also.

Soon as you don't they will leak, then back apart............

STUDY the way the springs at/near the sync adjusters are arranged before you take it apart. Some close up pics may be helpful for reassembly.

Just go slow, watch closely as you remove parts.

You will have to re-set the carb sync after it's back together.



Good luck,

SemiFast

I'll keep you posted.. Tnx!
 

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Split it.

I will stay tuned. Might have to do the same job one day. I have two running 4 cylinder Yamahas, plus a spare.
It is nice having guys that work on these things all the time. It is easy to get rusty when you do not.

Unkle Crusty*
 

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Sounds to me like a bad needle valve seats, in addition to the bowl gaskets either A. being bad, or B. improper install.
 

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Discussion Starter #13
Finally got the rings. In the process of replacing them now. Old ones were shredded! 20 years of rust and gunk build up. After seeing them it's no surprise at all they were leaking. Will test out tomorrow!
 

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Discussion Starter #14
Full rebuild complete, tested the carbs, all four no leaks.l!! .. Number 4 carb float fuel check came in a little low. Measure height was a perfect 17mm for all 4.. Thoughts?

Also, last time I started the bike back up it would only run on full choke but died as soon as I hit the gas. I was thinking maybe the choke cable came out of adjustment during rebuild? I did NOT take out the pilot screws during the last round but I took them out and cleaned them up this time. They were all in different sequence. No 1 @ full turns, [email protected], [email protected] and [email protected] .. I set them all back to 2.5 turns.

Before I put this thing back on the bike I wanna know what else I should possibly xheck for. I'd hate to put it back on and not be able to run it if the choke issue persists.

Thank for everyone's help so far!
 

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The fuel level is the only thing to be concerned about. The float height is just a bench setting. As long as the float is not sinking, your good.
Only runs with the choke on? Pilot jets and/or pilot circuit ports in the carb body plugged every time.

With all of the jets and the emulsion tubes (the pipe thingy the main jet screws into) out you can check and clean the internal passages with B12 chemtool spray.

It's not uncommon to find the fuel mixture screws adjusted the way you found them. (Don't care what the text book says).

When you're done you'll be a carburetor expert.
 

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Discussion Starter #16
Only runs with the choke on? Pilot jets and/or pilot circuit ports in the carb body plugged every time. /QUOTE]
It's weird though, I blew I'm out with compressed air and made sure they weren't plugged. Nadda.. Those puppies were as clean as could be. ??



SemiFast;1823514With all of the jets and the emulsion tubes (the pipe thingy the main jet screws into) out you can check and clean the internal passages with B12 chemtool spray.[/QUOTE said:
I couldn't get the emulsion tubes out of the jet area slot. Idk but I can see right through it. I assumed it was totally clean. I hit it with plenty of carb cleaner. Thoughts?
 

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Discussion Starter #17
Figured out why my bike needed to be on full choke .. The needle holder in the number 2 carb is missing!!! FML it's a discontinued part lol. I'm having no luck with this thing. Live and learn! Yeah I think now I'm a carberator expert lol
 

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make sure you bench synch

A bench synch is the best synch (only choice for us poor folk)unless you have a set of electronic EGA testers and a lot of time.

heres the procedures...


place the carbs on a large bench area that will allow you to get a bright flashlight to reach inside both sides(intake side and exhaust side both)

close the butterfly of the index carb, which is usually #2 with the idle screw until no light penetrates from the intake to the exhaust.

synch the second carb which is usually #1 to #2 using the adjustment screw between them, until the two butterflys open and close precisely at the same instant.

synch the 3rd and 4th carbs so they open and close together, using the adjustment screw between them, and then synch the four together as a unit.
Remember to test the idle screw each time you adjust the synch screws, because it is sometimes hard to get them right. You will need a manual if you have pulled the rods and don't know how they fit back together. check the pictures in the repair book, or take a look at other bikes like yours.

The secret is getting all four butterflys to open and close at the same instant.
Setting #2 as the lead carb is often done by pros because it contains what is called the idle jet, which is usually not present on all the other carbs. You can tell which carb is the lead carb, because there is an indentation along the edge of the butterfly, that matches the idle jet screw in the throttle body.

good luck with that.
 

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Figured out why my bike needed to be on full choke .. The needle holder in the number 2 carb is missing!!! FML it's a discontinued part lol. I'm having no luck with this thing. Live and learn! Yeah I think now I'm a carberator expert lol
I would suggest that you get the needle holder OEM replacement number and place it on any search engine like Google. Even discontinued parts will show up as used parts or new old stock [NOS] and be for sale by individuals or specialty shops who buy the discontinued parts.
 

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Clip it.

What Slum said.
Also many places that sell aftermarket products, or a scrap yard, will have bins of small pieces like the clip you need.

Can I assume you did not check the pin height of all four. Too, sometimes they are not installed correctly by previous folks. I start with the clip in the middle spot and go from there, adjusting the main jet size as required. In the case of Yami which was just a tad rich, is was easier to drop the needle one spot.

Keep up the good work. It can be frustrating, but worth it in the end.

Unkle Krusty*
 
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