Carburetor Rebuild & Tune (CV)

The Keihin CV carburetor was Harley-Davidson's preferred induction system through the Evolution era and into the early Twin Cam years. It's an excellent design — smooth, responsive, and tunable — but it needs periodic rebuilding as rubber components wear, ethanol in Canadian pump fuel attacks the needle seat and float components, and jets can clog from storage gum deposits. A proper rebuild restores like-new throttle response and fuel economy.

What's Included

• Carburetor removal from the motorcycle
• Complete disassembly and ultrasonic or solvent cleaning of all components
• Float needle and seat replacement
• Accelerator pump nozzle inspection and replacement if worn
• Diaphragm inspection — replacement if cracked or porous (common on older carbs)
• Float bowl o-ring and fuel inlet seal replacement
• Jet sizing consultation based on your air cleaner and exhaust combination
• Pilot screw access and adjustment (drill out factory cap if not already done)
• Reinstallation and hot idle adjustment

Ethanol and Your Keihin CV

Nova Scotia pump fuel is E10 (10% ethanol). Ethanol is an excellent fuel but it's hygroscopic — it attracts water — and it attacks certain rubber and plastic compounds. The Keihin CV's original needle seat and float needle are particularly vulnerable. If your bike has been stored over winter with old fuel in the carb, a rebuild is the correct spring prep step rather than hoping the carb will clear on its own.

When to Rebuild vs. Replace

The CV carb is worth rebuilding when: the body is not cracked, the slide bore isn't worn oval, and the vacuum port threads are intact. When a carb has been run dry-cracked repeatedly or the body is damaged, upgrade to an S&S Super E or Super B. We'll advise you honestly on which makes more sense for your specific carb.