clear tube method for setting float

[coffeemandave]

I have my carbs off for cleaning and want to set the floats using the "clear tube method" Can anyone help with the specifics on doing thiis?

[jim snyder]

Since SISF is out of pocket I will assist you. With carbs level attach clear fuel line tube to bottom drain.
Hold tube along side of carbs and open drain screw. Allow fuel to acquire its level (you may need to dip it down to allow the air bubble out. Correct fuel level should be right at the bowl gasket line to
1 m/m above. Try and get all of them within 1 m/m of each other.

[kzz1king]

For holding the carbs I used a vice grips that I drilled a hole in and screwed it to the side of a 2x4 which was fastened to the bench. I sometimes had to squeeze  the air out of the line with a pliers. I cannot remember but you are only supposed to raise or lower the hose to avoid a false reading.

[mdr]

Don't know where, but I recall seeing someone making a 'jig' out of PVC pipe to hold the carbs during servicing.  'Twas pretty cool, but not really necessary, but did I say it was pretty cool?

If you lower the hose it'll pull more fuel out of the bowl, lowering the apparent level unless you have enough gas in the fuel line to refill it.  Best practice is to have the fuel tap on PRIME so you know you've got enough, or use an 'auxiliary fuel tank'.   Raising the hose will make fuel flow back into the bowl, raising the level.  Once gas gets past the float valve, it can't go back so the level will look like it's set too high.  So down is better than up.

Biggest problem I have is air bubbles trapped in the drain nipple.  I try to clear it by:
- hose looped up as tight as possible, end of the hose OVER THE FUEL TANK (so if there's a float valve problem I don't get gas everywhere).
- open the drain valve (hose on the nipple already, natch).
- blow about 1" of gas back up into the fuel bowl to dislodge the bubble.
- lower the hose to let the I blew up into the bowl back out.  Lower it a couple more times to recheck the level to make sure it's repeatable.

Take the time to get this right.  It's the most basic of all the carb adjustments.  Screw it up and you'll never get anything else right.

[RFH87_Connie]

Screw it up and you'll never get anything else right.

I don't think I have ever read it any better than that!  So true!

Edit:   Oh yeah, here's my cheap jig.

[Nosmo]

Don't know where, but I recall seeing someone making a 'jig' out of PVC pipe to hold the carbs during servicing.  'Twas pretty cool, but not really necessary, but did I say it was pretty cool?

If you lower the hose it'll pull more fuel out of the bowl, lowering the apparent level unless you have enough gas in the fuel line to refill it.  Best practice is to have the fuel tap on PRIME so you know you've got enough, or use an 'auxiliary fuel tank'.   Raising the hose will make fuel flow back into the bowl, raising the level.  Once gas gets past the float valve, it can't go back so the level will look like it's set too high.  So down is better than up.

Biggest problem I have is air bubbles trapped in the drain nipple.  I try to clear it by:
- hose looped up as tight as possible, end of the hose OVER THE FUEL TANK (so if there's a float valve problem I don't get gas everywhere).
- open the drain valve (hose on the nipple already, natch).
- blow about 1" of gas back up into the fuel bowl to dislodge the bubble.
- lower the hose to let the I blew up into the bowl back out.  Lower it a couple more times to recheck the level to make sure it's repeatable.

Take the time to get this right.  It's the most basic of all the carb adjustments.  Screw it up and you'll never get anything else right.

That was me.  Here's how I set mine up for checking the fuel levels.  I don't use any sort of aux fuel tank, I just run a 5/16" hose from the tank to the carb inlet hose.

pics below

[Summit670]

You only need 1 piece of hose to attach to bottom of carb.  Make sure it is 12" long or longer because it makes it easier to get air bubbles out.

Keep hose open end high to start out, then start lowering it little by little and you will work out the air bubble and you will begin to see the level at which the fuel stabilizes in the tube.

For the center carbs, you can run the hose to the outside carbs seams to make it easier to see.  Just make sure the top of all the carbs are level with each other using a straight edge.

Oh, and I c-clamped the heavy L angle iron which connects all the carbs, clamped it to a short piece of light duty angle of the type they hang garage door openers, then I put a few lag bolts into a 2x4 and was able to then slip the clamped carb/light duty (it had the pre-drilled holes along the length) onto/over the bolt heads, then the assy dropped down a little and the bolt heads kept the angle in place.  The 2x4 thingy was square, like 12x12.  I then sat it on the edge of my snowmobile trailer.  Had to place a weight on the backside of the square to hold the back down.