1978 XS float adjustment, gas line

[jeffro1954]

I have read on here that the float height should be measured from the carb body without the gasket. My handy Clymer book informs me it's 27.5 mm with the gasket. gasket width is enough to throw things off I suspect.

Also is it correct that the fuel line should drop below the float bowl and loop up into the T? Or should it angle straight down to the T from the petcock?

[jeffro1954]

1978 float height

Correction float height is 25.7m or 1.012 inches above gasket surface.

[DGXSER]

Hmm...reread the Clymers or get a reprint. Everything I ever read said from the gasket surface meaning without the gasket in place.

For that year if the carbs are original then yes 25.7mm from the carb gasket surface, no gasket in place.

[dbeardslee]

It's without the gasket in place, and there's a range from 24.5mm - 26.5mm that's acceptable.

[Larrym]

Private joke

If you set the float levels to 1 inch above the metal surface you can walk away and call it as good.

It's a little private joke the Yamaha engineers have played on us americans. 2.54 centimeters is equal to one inch. 25.4 millimeters equals one inch. It's kinda fun to see us all fuss over that last .3 millimeters like it's a life or death situation.

The real fun starts when you change the bike's fluids and have to convert CC's to ounces and such.

Enjoy!!

I've seen people do it both ways with the fuel Tees and the fuel line loops. Mine loop under the carbs, into inline filters, then up to the fuel Tees if that helps.

[jeffro1954]

carb adjustment

As it turns out I used the right approach 1" measured over the bare metal. having trouble with idle so going over steps to figure it out. Still need to synch the carbs once I get my hands on gauge to do it with. runs fast still warms up, starts to settle down but then it starts back firing and missing.

Still wondering about the second part of question. does the fuel line make a loop down and up to connect to the tee or more like a 45 degree angle to it. Need a fuel line schematic/elevation for my simple brain.

[jeffro1954]

sorry, didn't read your answer all the way through. thanks for the feedback on the fuel lines

[Larrym]

S' ok.

Look here in the tech tips:

http://www.xs11.com/xs11-info/tech-t...l-filters.html

has one way of routing lines and the fuel filters...

[DGXSER]

You know that story about the 1" is interesting, and that falls within the tolerance range. I will say though that back in the 70s when the big 3 were getting into the 4 cyl market the story I heard is that Ford had taken one of their 4 cyl and laid it out next to a Datsun 4 cyl and found no difference yet the Datsun lasted so much longer. Then they got some more accurate tools to measure with and found ALOT of differences.

[Larrym]

A Thin Line

I admit that the closer anyone can get to the ideal settings on just about anything the closer one gets to having the unit perform the way it was designed to. I just think it's funny that the difference between setting our float levels at one inch with a ruler and the "ideal" setting leaves us with a margin of error less than the line made by a sharp pencil.

I was a mechanic during those times when the imported engines were outlasting the domestics. The mindset of the industry was that the motors didn't have to last as long because you could just replace or rebuild the motor when it died. Today it's the worst combination possible: you can replace/rebuild the motor but it costs more than getting another entire vehicle.

Precision has its costs.