Carburetor Jet Kit Install

When you install a high-flow air cleaner or aftermarket exhaust on a carbureted Harley-Davidson, the stock jetting is no longer correct. The factory jets were calibrated for the restrictive stock intake and exhaust — adding flow without adjusting fueling creates a lean condition that causes overheating, backpopping, and potential engine damage. A proper jet kit installation brings fueling in line with your modifications.

What's Included

• Carburetor removal
• Float bowl and needle removal
• Main jet replacement to correct size for your modification level
• Pilot jet replacement (if running lean at idle/off-idle)
• Needle clip position adjustment (enriches or leans mid-range)
• Pilot screw adjustment for best idle mixture
• Road test and fine-tuning

Jet Sizing Guide

For a Stage 1 setup (open air cleaner, slip-on exhaust): main jet typically increases from stock #168 to #175–#185. Needle clip moves to 4th groove from top. Pilot screw is set to 2.5–3 turns out from lightly seated.

For a full exhaust system (headers + mufflers): main jet increases to #185–#200 depending on the header design. A dyno session gives the most accurate final numbers.

Spark plug reading after a hard wide-open run confirms jetting: tan to light brown = correct; white/grey = too lean; black/sooty = too rich.