20
Carburetors and Initial Tuning
Your Ultima
®
engine has been supplied with a Mikuni Carburetor that will require initial setting to be made prior to Initial start-up.
Typically higher
elevations or hotter climates will require different jetting and ignition timing than those shown in this guideline. At any elevation it is
important that your initial tune is not excessively rich, which is indicated by excessive black smoke, and equally important, avoid running the
engine lean for the initial break in as this condition creates heat fast. Prior to starting your engine you should check your carburetor’s initial
idle mixture setting and fuel pump setting recommended by the manufacturer. Ultima
®
provides the proper base line jetting for each engines
size but idle mixture and fuel pump setting must be done on an individual basis. When selecting the initial jetting for your engine remember
that exhaust systems and ignition settings can have a great effect on the engine’s fuel demands.
An experienced tuner should make the final decision for your particular jetting and timing needs with your combination and at your elevation.
Thoroughly read and understand your carburetor instructions before installing it or starting your engine.
Baseline Jetting Suggestions
80 CI 96 CI 100 CI 107 CI 113 CI 120 CI 127 CI 130 CI 140 CI
Mikuni 42mm 160/22.5 160/22.5 165/22.5 165/22.5 170/25 - - - -
Mikuni 45mm - - 170/22.5 170/22.5 175/27.5 185/32.5 185/32.5 185/35 -
Mikuni 48mm - - - - 175/25 185/32.5 190/35 190/37.5 195/40.0
S&S ‘G’ 72/28 74/29.5 76/29.5 78/29.5 78/31 80/31 84/31 84/33 -
S&S ‘D’ - - - - 82/31 84/33 88/33 90/33 92/36
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