Float height, am I doing this right? Pics

Am I doing it right? I'm setting my ruler right on top of the gasket so I'm subtracting a mm from the specs. '79 carbs so I'm looking for 24mm or 23mm on top of the gasket.

You're doing it right. Sight across both floats. Then put the ruler on the other side and sight across the tops of both floats again. Make sure the weight of the floats is not pushing the valve needle plunger down. The tang on the floats should just be making contact with the plunger, not pushing it down.

There is usually a little free play in the spring-loaded pin (which is normal and fine). The weight of the float will push that little bit of the pin in. Just make sure it's not compressing the pin fully. Gently push the float down against the pin and observe it's tang compressing it fully, then springing back out when you release pressure on the float. That spring loaded pin needs to be functioning, not gummed up and stuck.

I cut out a small wooden U shaped gage that will span both floats which tells me that both floats are the same height. Then it get thrown in with the special tool tray. Then I double check with the clear tubing and gas. It's always very close.

I use a 4 inch adjustable machinist's square, and lay the body across both floats with the beam adjusted to the correct height. If it's high, it don't touch. If it's low, it "slides off" as I drag the tool away from the bottom of the float. Some will reccomend a double check with the clear tubing on the housing flange. It's cheap insurance against getting the carbs all the way installed and discovering that one of them is off.

Ok cool, how are you attaching the clear tubing and where should the fluid level be when compared to the outside of the carb body?

You are measuring from the gasket and subtracting a mm for the gasket. Is your gasket a mm thick? I just remove the gasket. Then you can just measure it without the matnmatics.
The clear tube hooks to the drain plugs in your float bowls. In your 77 carbs that means drilling a hole through one of your drain plugs and install the piece of tubbing to hook the clear hose to.
With this set up you hold the caerb upright as it would be on the bike. Hook a fuel line to the fuel inlets. Turn on the fuel. I like to use the fuel tank with the petcock. Just as on the bike. While holding the clear hose up along the side of the carb as fuel fills the float bowl fuel comes up the clear hose. when the float shuts the fuel off the fuel level in the clear hose is the level of the fuel in the float bowl. This level in the clear hose should be just below, within 1 mm, of the gasket.
If you have the Yamaha factory manual for the early years it explains, with pics of just how the carbs work and how to test the fuel level with the clear hose.
Leo

Ok, awesome. Unfortunately, I only have the Haynes manual but what you are saying makes sense. Thanks Leo.

If you don't want to drill your drain bolts apiece of gas line (3/8 iirc) will "screw" into the drain hole for this test.
re: the needle pin you might want to check to see if it is moving freely. The little spring seems to get gunked up on mine. I can push it down or pull them up but the spring doesn't return it. I put them in a bottle top with the pin soaking in carb cleaner but the tip dry to remedy.

^Same here. And if after a good cleaning the spring still doesn't move like I'd like it to, I do the measurements in the extended position, and try to keep it there through the re-assembly.

I've never used the tube method. I think it's way too touchy for fractional mm measurements. Instead I've gotten real good at getting the carbs off and back on.

xjwmx said:

I've gotten real good at getting the carbs off and back on.

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Haha, story of my life at the moment.