Charon
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I was looking through a book I have about the Nebraska Tractor Test lab in Lincoln, NE. It lists results of tractor tests from the inception of the lab up through 1984. It includes gasoline, propane, "tractor fuel" and diesel tractors. The part of interest is a large table of economy figures, telling how many horsepower-hours are produced per gallon of fuel. There are over 400 gasoline tests, and as best I could tell (besides a few outliers) the results ranged from roughly 8 to just over 13 horsepower-hours per gallon. My unscientific method of choosing the mean was to go to the middle of the list, where I found about 11 horsepower-hours per gallon to be pretty common. These measurements are made with the tractor at full power pulling a load, so might be reflective of a motorcycle engine running wide open. If we relate this to the Savage/S40, and generously grant it 33 horsepower, it burns three gallons of fuel per hour, max. If we claim to have gotten another 11 horsepower with performance mods, it makes 44 total and burns four gallons per hour, max. Now, someone needs to measure the fuel flow for the standard petcock and the Raptor. I may get a chance to try it with the standard petcock, but don't hold your breath waiting (you might turn blue).
The point I am trying to make is that we need to get some real numbers instead of anecdotal data. The Raptor does not depend on engine vacuum for operation, so it should be easy to measure fuel flow. Take the fuel line off the carburetor, run it into a calibrated measuring device such as a kitchen measuring cup, and time how long it takes to flow a measured amount such as a quart or even a pint. Convert that to gallons per hour. Even better would be to run a full two gallons, which would allow for differences between a full tank and a mostly-empty one.
The factory petcock would be a little more difficult, although it could be measured in PRIME just like with the Raptor. Measuring in ON or REServe would require that vacuum be applied, easy enough with a large syringe or maybe even a turkey baster. But to really characterize it would require a vacuum source and a vacuum gauge, to see just how much vacuum is required to initiate fuel flow and whether fuel flow is proportional to the amount of vacuum applied. Not difficult to do, but tedious.
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