carb questions

[venture83_98]

My '86 has about 500 miles on it since carb rebuild (including all rubber parts and the diaphragms ), valve adjustment, carb synch, new fuel pump, lines and filter. Also had the tank lined.

 

I am sometimes getting gas coming out one of the overflows and get a gas smell most of the time. I checked the plugs and cylinder #'s 1, 2 , and 3 look like the plug in the first pic. cylinder #4 is in the second pic. It was wet with fuel.

 

I took the tops off the carbs and noticed that cylinder #2 had fuel on the top of the diaphragm. It looks like it came through the hole in the slide.

 

I am thinking that #4 has a high float level. But am not sure. Any input would be appreciated.

[MiCarl]

Agreed. #4 is over filling. Did you check the fuel levels when you did them? Do you know how to check them now?

[venture83_98]

Agreed. #4 is over filling. Did you check the fuel levels when you did them? Do you know how to check them now?

 

My problem is that 3 of the 4 fittings are broken off. Somewhere on here i found a post that gave a measurement for setting the floats from the base of the carb. It looks like they are available from Yamaha, but I am not 100% sure. It looks like it may be #42, but not sure.

[MiCarl]

No, unfortunately #42 is not the fitting. The fitting is/was not sold separately from the carb body.

 

You can dry set them. While not perfect that should get the level close enough that it doesn't overflow. I think it was Squidley did a measurement some time back. IIRC the measurement was 1" from the bottom of the chamber to the top of the float just when the needle closes (you don't want to invert it where the float might compress the spring). Bottom line is the float should be pretty much horizontal (as installed on the motorcycle) when the needle closes.

 

If you didn't replace the needles you might want to do that when you tear them apart.

[venture83_98]

 

You can dry set them. While not perfect that should get the level close enough that it doesn't overflow. I think it was Squidley did a measurement some time back. IIRC the measurement was 1" from the bottom of the chamber to the top of the float just when the needle closes (you don't want to invert it where the float might compress the spring). Bottom line is the float should be pretty much horizontal (as installed on the motorcycle) when the needle closes.

 

If you didn't replace the needles you might want to do that when you tear them apart.

 

Needles were replaced. I believe that is the procedure I used. Guess the carbs come off again.........

 

Now I need to borrow a carb tune again.........

[MiCarl]

Before you pull them off......

 

Shut off the fuel tap. Idle the motorcycle until it starts to stumble then switch the fuel back on. See if the problem clears up.

 

It's possible you picked up a piece of debris out of the fuel line or something and the above procedure may flush it out.

[Marcarl]

This is how I set my floats:

Install the needles, fit the float in position, turn carb upside down. Now look at the float at eye level. The curved indent in the top-center (now bottom center)of the float, should match the round circle in the main jet body that is left there from casting it. If it's not right then bend the tab to make it right. I did mine this way and then bench, wet, checked them. None needed to be re-adjusted.

[frankd]

As Carl said, you may want to flush any garbage from the needles and seats, but I did this a different way, and I think it'll work better. On the left side of the bike, (underneath the left cover) you will see a 2 wire connector near the passenger left foot peg. Put the bike on the center stand, start it, and disconnect this connector. This is the fuel pump connector. When the bike starts sputtering (about 2 minutes) plug the fuel pump back in and the bike should recover. Do this a couple of times.

 

Frank