Tuesday, May 25, 2010

Tuning Yamaha FZ 16 Carburetor

Note: Follow the below instructions at your own risk. However I will be here to help if things go wrong. 



Tool required: Screwdriver


Things to do before you tune your bike.


1. Clean the air filter.
2. Clean spark plug and make required adjustment.



The first thing you should know when it comes to tuning Yamaha FZ 16 is understanding which jets control the fuel flow at a particular throttle position.

Throttle positions:

Closed to 1/4th open: Fuel screw on the bottom of your carb (Pilot Jet).
1/4 - 3/4: Needle Jet
1/2 - Full: Main Jet

Here we will discuss only about the Fuel Screw.




Where is the fuel screw in Yamaha FZ 16?


In Mikuni Carburetor the fuel screw is close to the engine side on the left. It a minus head in golden color.





Before you touch the Fuel screw:




It’s important to note the current position of the fuel screw.


1. Turn off the engine.
2. Turn the fuel screw clockwise while you make a note of the number of full turn it took to reach the close position (Turn the fuel screw clockwise till it closes).
3. Now put the fuel screw back to the default position (Turn it anti-clockwise)



How to adjust fuel screw?

Turning the Fuel screw clockwise will reduce fuel flow: Lean mixture.
Turning the Fuel screw anti-clockwise will add more fuel: Rick mixture. 

Let’s get started:

1. We need to warm up the engine. Not just starting the engine; Ride your bike for 10 to 15 minutes.

2. Bring the bike to fast idle (Turn the idle screw clockwise till the RPM hits 2000)

3. Now use the screwdriver to slowly turn the fuel screw clockwise till the engine RPM drops. Note some bike will still run when the fuel screw is completely tight.

Now the bike is running at the leanest point.

4. Now slowly turn the fuel screw anti-clockwise 1/2 turn at a time (180 degree or half turn)

Wait and listen to the engine RPM and continue turning anti-clockwise 1/2 turn at a time.

You will hear the engine rpm begin to speed up.

Stop turning the fuel screw at the point when the engine hits peak rpm (At this point the exhaust note will be crisp). 
Peak rpm is when the engine runs the cleanest and fastest. 
When you reach that point, turning the fuel screw anti-clockwise won't increase the rpm further.

Note: Turning the fuel screw anti-clockwise further from the above point, the rpm will stay up but the exhaust note will become dull.

5. Now turn the idle screw anti-clockwise to bring the rpm back to 1000 or 1500.

6. Now take a test ride. 

Did I get the correct Air/Fuel mixture?

1. Twist the throttle the response should be quick and crisp. 
2. There should be no hiccups when you ride.

What fuel economy can I expect on Yamaha FZ 16?

40+ Km/lt if speed below 55kmph.
35 to 40 km/lt if speed is 60 to 80kmph

My Bike Photo 1 

My Bike Photo 2