2001 Yamaha 650 Carburetor Choke Fix – Smooth Engine Performance
Introduction
The 2001 Yamaha 650 is a well-regarded cruiser known for its reliability, smooth ride, and classic V-twin performance. However, like all carbureted motorcycles, it requires proper choke function to ensure smooth cold starts and consistent engine operation. The choke system temporarily enriches the air-fuel mixture, allowing the engine to start more easily when cold. If the choke is not functioning correctly, you may experience hard starting, rough idling, excessive fuel consumption, or poor throttle response.
A malfunctioning choke can lead to various performance issues, including engine bogging, black smoke from the exhaust, and even stalling after warming up. Fortunately, adjusting or fixing the choke on a 2001 Yamaha 650 is a straightforward process with the right tools and guidance. This article will provide step-by-step instructions to diagnose, adjust, and repair the choke system for optimal performance, ensuring your bike runs smoothly every time you hit the road.
How Does the Carburetor Choke Work?
The choke system on the Yamaha 650’s Mikuni carburetor works by restricting airflow to increase the fuel concentration in the mixture when the engine is cold. When the choke is engaged, it allows the engine to start easily and warm up quickly. As the engine reaches operating temperature, the choke should be gradually turned off to avoid excessive fuel consumption and a rich-running engine.
If the choke is not working properly, your engine may run too rich (too much fuel) or too lean (not enough fuel), causing poor performance. Over time, dirt, fuel residue, or mechanical wear can cause choke components to stick or malfunction, requiring adjustment or replacement.

Signs of a Faulty Choke on a 2001 Yamaha 650
A faulty choke system can cause several performance issues. Here are some common symptoms that indicate your choke may need adjustment or repair:
- Difficulty starting the engine in cold weather
- Rough or erratic idling
- Excessive fuel consumption and black smoke from the exhaust
- Engine bogging or stalling after warming up
- The bike runs too rich or too lean, affecting throttle response
- The choke lever or cable feels stuck or unresponsive
If you experience any of these symptoms, it’s time to inspect and adjust the choke system to restore proper functionality.

Tools Needed for Choke Adjustment
Before working on your Yamaha 650 carburetor choke, gather the necessary tools:
- Phillips screwdriver – For loosening screws on the carburetor and choke components
- Adjustable wrench – For adjusting the choke cable and tightening nuts
- Carburetor cleaner – To remove dirt and carbon buildup
- New choke cable (if necessary) – In case of cable wear or stiffness
- Shop rag and gloves – To keep your workspace clean and protect your hands
Step-by-Step Guide to Adjust the Choke on a 2001 Yamaha 650
Step 1: Locate the Choke Cable and Mechanism
The choke knob is typically located on the left side of the carburetor. It connects to the choke cable, which runs to the choke plunger inside the carburetor.
Step 2: Inspect the Choke for Wear or Blockage
- Remove the choke knob and examine the cable for fraying or stiffness.
- Check if the choke plunger moves freely when engaged and disengaged.
- Use carburetor cleaner to clean any buildup around the plunger and cable.
Step 3: Loosen the Choke Locknut
- Use an adjustable wrench to carefully loosen the locknut securing the choke cable.
- This allows you to adjust the choke’s positioning for proper function.
Step 4: Adjust the Choke for Smooth Operation
- Gradually pull the choke knob and observe the RPM response.
- The engine should idle smoothly without excessive stalling or bogging.
- Adjust the cable tension to ensure the choke opens and closes fully.
Step 5: Secure the Choke and Test the Engine
- Once the correct setting is achieved, tighten the locknut securely.
- Start the engine and test the choke under cold and warm conditions to ensure it operates correctly.
Common Choke Problems & Troubleshooting
If your choke is not working properly, try these troubleshooting steps:
Problem 1: Choke Stuck Open
- Symptom: Engine runs too rich, excessive fuel consumption, black smoke from exhaust.
- Fix: Clean the choke plunger and cable with carb cleaner, ensure smooth movement.
Problem 2: Choke Stuck Closed
- Symptom: Hard starting, rough idling, engine stalls when warm.
- Fix: Check for cable obstruction or damage. Lubricate or replace if necessary.
Problem 3: Choke Doesn’t Stay Engaged
- Symptom: Choke disengages too quickly, causing stalling.
- Fix: Tighten the choke tension screw to hold it in place longer.
Problem 4: Choke Cable is Worn or Broken
- Symptom: The choke lever feels loose, unresponsive, or stiff.
- Fix: Replace the choke cable with a new one for better performance.
FAQs
1. How do I know if my choke is stuck?
If your engine runs rough, has difficulty starting, or you notice excessive fuel consumption, your choke may be stuck open or closed.
2. How often should I adjust my choke?
You should check your choke system whenever you experience hard starts or rough idling. Regular maintenance ensures smooth performance.
3. Can I ride with the choke on?
No, riding with the choke on for too long leads to excessive fuel consumption, carbon buildup, and poor performance.
4. What if adjusting the choke doesn’t fix my problem?
If adjusting the choke doesn’t help, you may have a dirty carburetor, clogged jets, or an incorrect fuel mixture. Cleaning or rebuilding the carburetor may be necessary.
5. Does weather affect choke performance?
Yes, colder temperatures require a longer choke warm-up period, while warm weather may need minimal choke use.
6. Can I replace the choke cable myself?
Yes, replacing a worn choke cable is a simple DIY task requiring basic tools and a new cable.

Conclusion
Proper choke adjustment and maintenance are crucial for ensuring smooth engine performance on your 2001 Yamaha 650. A well-functioning choke helps with cold starts, improves fuel efficiency, and prevents bogging or stalling. By following the steps in this guide, you can diagnose, adjust, or fix your choke system, ensuring a smoother and more enjoyable ride. If problems persist after adjusting the choke, consider cleaning or rebuilding the carburetor for optimal results.