TOPIC:

So I've been flying around a lot lately, and I was thinking of a quick way to accurately set float heights without rechecking service fuel level and reinstalling carbs several times.

I dug into my fluid dynamics knowledge and realized that design fuel level (measurement from bottom of float to carb edge) may work if you are sure the float's buoyancy is still good. It's not as accurate as service fuel level, but it's probably within 1 or 2mm, which isn't bad considering my floats were all over the place!

So first I floated my floats in some gas and measured the buoyancy of the float (ie. volume of water it displaces. note - they will always displace their weight in water). BTW, don't use bare hands like I did.. oops!

I measured the water level of each float, they all worked out to be close to 15mm.

Then I installed the floats and pushed them just until it lightly pressed against the float valve. I then bent the tang until I got a design level of about 19mm, which places the fuel level about 4mm below the edge of the carb as you can see in the photo.

This seems to have worked fairly well for me. I've been too lazy to double check this with a service fuel level check, but the performance sure seems to have proved that it worked!

Let me know if I'm totally off my rocker!

... "Aluminum Rules".. Get it?? ahahaha

Post edited by: inline79, at: 2007/05/10 01:46

inline79 wrote:

... thinking of a quick way to accurately set float heights without rechecking service fuel level and reinstalling carbs several times....

Checking actual service fuel level is quick and easy with carbs on bench or on bike. Save time and effort by using only one float bowl screw to attach the bowl while measuring the level. Any change or successive change in the float tab should be miniscule as this is a very sensitive adjustment. When refilling the empty float bowl (carbs on bench or on bike) keep the clear tube held firmly against the top edge of the bowl very still and immobile so the level inside the tube reflects the exact same level inside the float bowl -- if the tube moves, you may get a false reading. Of course, for an accurate check, the carbs must be kept level whether on or off the bike. In summary, with float bowl empty (attached to carb -- one screw being sufficient) and clear tube affixed into bowl drain hole and held steady against top of bowl, and carbs level, turn on gas and watch as tube fills until gas quits flowing. The level inside the tube then matches the level inside the float bowl.

Memo -- Took longer to read this post than to check a carb's service fuel level.