How do you know that each of the cylinders of a multi-cylinder engine is operating at its best? How do you know if each receives the same intake airflow or the same fuel mixture strength? Maximum power is given when each cylinder receives an air/fuel mixture close to 12.5 to 1. Let's say we have two cylinders actually receiving that, while cylinder three gets a lean 15:1 and the last cylinder gets an over-rich 11:1. Two cylinders are making their maximum, but the lean and rich cylinders are falling short by a couple of horsepower each. With this engine running on a dyno, the calculation resulting from fuel- and airflow numbers would tell us the mixture is correct. As an average it is, but we know the engine is down on power. How can we correct this? The old way was to "read" the mixture from the sparkplugs and then "stagger-jet" the carburetors accordingly. For example, because of the way the 1970-71 Kawasaki H1-R racing two-stroke Triple vibrated, its wildly shaking left carburetor required a #320 mainjet, its fairly active right carburetor a #310 and the quiet center a #300.
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