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Old 06-16-2013, 03:25 PM   #17
because I can
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 9,116
Originally Posted by Plaka View Post
You have a problem talking about boobies (esp. with pictures)?

I'd get the levels equal for tuning purposes on the stand. Out on the road they are going to be jumping around so much that it would take some fine and fancy statistics to tell what they are.

It occures to me that the really easy way to set very accurate levels is to determine where the top surface of the fuel is with respect to some reference on the jet stack. Then, bowl off, just hold a small glass dish under the carb, and touching it to hold steady, turn on the gas and see where the top of the fuel is with respect to your mark when the float shuts it off.

You still have a chicken and egg problem to determine where the level "should" be when the float is "correctly" adjusted. I would go by what makes your jetting work well. You can tweak the jetting by tweaking the fuel height.

What matters might be worth determining. Compute how much of a change in fuel depth will change the delivery pressure some arbitrary amount. You can look up that calculation.

Then take a guess at how much the depth changes as the fuel sloshes around.

lastly measure the depth in the bowl and with a bit of arithmetic compute the percentage change in pressure mm/mm with depth.

Compare that with your guess on the slosh pressure change to get an expected variation in pressure.

Don't sweat setting the fuel depth to a tighter tolerance that that expected variation. You're gilding a toad.

One procedure for setting the float is to run fuel into a can and lift the float with your finger until it just shuts off. Float seam should be parallel with carb bottom. This does not account for variation in float buoyancy but it's good enough and quite consistent otherwise..
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