When I purchased this 81 KZ1300 it came with a second exhaust system a DG six into one. While I was doing the standard new bike going thru: valves, tires, fork seals, brake calipers and a new seal on the water pump impeller, I got a little too enthusiastic and installed the DG exhaust system before I had any sort of baseline for the bike. I didn't ride the bike much but every outing, followed by some cobbling and fiddling, resulted in some small improvement in driveability.
At first, I struggled with sooty plugs and occasional weeping from the carbs till I checked the fuel height and found it to be above the gasket line on the float bowls. I believe the correct height is 5.5 to 8 mm BELOW the gasket.
I'm wondering if the alcohol in modern fuels hasn't affected the black plastic foam floats. If the alcohol could enter the plastic foam it could make them heavier.
I set up a board with two carb connectors and used a piece of clear tubing to examine the fuel levels. At first I used a piece of 1/4" clear tubing because it would fit over the drain outlet on the float bowls however I found that every time I opened the drain screw a bubble of air would get trapped in the downward portion of the tubing. My readings were all over the place and certainly not repeatable. Eventually I came to realize that any air entrapped in the tube will distort the height of the liquid column as the tube is pulled up against the float bowl. I went back to the hardware store looking for smaller tubing. Fortunately, I found a size of tubing that fits fairly tightly inside of the 1/4" tubing. I used a short piece of 1/4" tubing to make a coupling into which I was able to shove the smaller tubing till it butted right up against the float bowl drain. With this smaller inside diameter when I opened the drain screw the fuel pushed all of the air ahead of itself leaving me with a completely filled tube which would fill up to the same height no matter how often I checked it. I was now able to correlate bending the float tang with higher or lower fuel levels. To get to the 5.5 to 8mm below the gasket I had to bend the float tang significantly. The end result was that I was now able to make sense of the changes that occurred as I varied the jetting. I've almost got the DG pipe jetted perfectly. More on the jetting later.
Bill
1947 Indian Chief, 1968 BSA Shooting Star, 1970 BSA 650 Lightning, 1974 Kawasaki W3, 1976 KZ900 A4, 1979 KZ750 B4, 1979 KZ750 B4 Trike, 1980 KZ550, 1981 KZ1300, 1982 KZ1100 Spectre, 1985 Kawasaki ZN1300, 1987 Yamaha Trail Way, 2000 Honda Valkyrie Tourer, 1981 GL 1100, 2009 Yamaha RoadLiner S
