Setting Float Height | GTAMotorcycle.com

Setting Float Height

theraymondguy

Well-known member
Setting float height without a manual can be a real crap shoot / setting up a carburetor in a custom application; Slobbering carb overflow tubes, inexplicably lean or rich running engines etc.

However, there is a way to nail it, every time.

Place a good sized piece of cardboard under your bike. You will inadvertantly spill some fuel, may as well be prepared.

Get the bike level front to back and side to side as best as you can. The more time you spend on this, the better the result. Avoid using the center stand without at least blocking the front end to prevent the height being thrown off.

Connect a healthy length of clear tube (Fluid transfer tube, available in different I.D.'s in the automotive dep't at CTC) to each carburetor drain spigot. Loop the clear tube upward in a gentle curve upward inline with the throttle valve (see pic), tie it tightly in place with ziptie as close to the center of the fuel bowl as you can manage.

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Open your fuel petcock (those whom have a vacuum lock on the petcock will have to draw a vacuum to allow flow), and open the drain screw. Observe at what height the fuel stops at:

Ideally, the fuel will stop rising at the seem where the float bowl meets the body of the carburetor.

If it stops slightly higher than the float bowl, your float height is set too high (will cause engine to run rich, possibly even stall down hill).

If fuel runs continuously through the overflow, you have a problem with the float valve (needle) or a sunk float (see solder on upper float in pic below).

If it stops below the float bowl, your float height is set too low (engine will run lean). The carburetor above has the float height set too low, and would run lean.

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