Subject: [FlyRotary] Re: Carbs


> Richard,
> You should seriously consider a clear float bowl. On engines capable of
> pulling high vacuum WOT often will drain the float bowl if you don't run a
> fuel pump. The resultant lean condition isn't good for your engine!
> Bill Jepson

Bill,
I saw that on the Mikuni web site for the 48mm carby, they suggested a fuel
pump. I didn't know you could get clear float bowls?
George ( down under)

Hi George,

Yes you can get some kind of clear plastic floatbowls. I didn' t see any on the Sudco site though. Lynn has already posted a good alternate method. This is called a fuel level tube. Kawasaki used to say you MUST use a fuel level tube on carb work. The old method of setting by measuring the float isn't always accurate. You can do the fuel level tube by attaching a fitting to the cap on the bottom of the carb.(This is the cheapest part to replace if you mess up too!) just a flexible hose to a clear plastic or glass tube surcured straight up does the trick. I wouldn't use this for anything but testing though. The top of the tube has to be open to work. Ok for bench testing however. Buy a spare cap and run the standard one.

 Fuel pump, yes gravity feed through too small a feed hose or restrictive fuel filter can kill your engine by draining the float bowl at speed. The Harleys had such a bad time with it that the S&S Super carb had a optional valve attached to the throttle that opened a feed directly into the carb throat with a small adjustable jet. It bypassed the float bowl altogether. It fell from favor because many harleys didn't have a return spring on the throttle and some dumb passerby could dump all the gas out of your fuel tank by turning the throttle past 3/4 open wher the valve opened and then leaving. The resulting flooded engine and possible hydraulic lock were a true pain in the ass. An electric or even a vacuum pulse fuel pump is the way to go.

 

 Bill Jepson