How To Adjust Idle On Fuel Injected Harley Davidson?

The positioning of an idle screw is essential when checking whether a bike uses a carburetor or fuel injection system. For a fuel injection bike, the idle level will determine how fast the bike will move when the brakes are released. Knowing how to adjust idle on fuel injected Harley-Davidson is essential, especially if the idle level becomes unusually low or high, as this may affect the overall speed output of the bike.

When there is an idle screw at one’s disposal, it becomes easy and timely to adjust the idle speed if the bike runs with a carburetor. However, for an electronic fuel-injected motorbike, the process becomes a bit tedious. Hence, many riders encounter problems with fuel injectors in the Harley-Davidson motorcycles. This comprehensive article contains the necessary details about the subject.

Can You Adjust Idle On Fuel Injected Harley Davidson?

Motorcycle idle speed refers to how fast the motorcycle moves when the brakes are released. Those with a fuel-injected bike can adjust the idle speed using a small knob. The knob sticks out of the engine compartment on the right or left side of the Harley-Davidson bike.

How Do You Know Your Harley Needs To Adjust Idle?

There are two ways to know if your Harley-Davidson idle needs to be adjusted. The first one is if the motorcycle idle is too low or if the idle is too high. The following paragraph will address the two possibilities and their potential causes.

How Do You Know Your Harley Needs To Adjust Idle

Motorcycle Idle Is Too Low

If the Harley-Davidson bike is warmed up and idling lower than the recommended level, the engine will stall or may not continue to run without the throttle getting added. The biker may also experience stalling during takeoffs. The second problem is that the oil pressure in the engine will become very low. Here are some possible causes of these problems.

  • Lean Air To Fuel Ratio: If the biker performs a body modification, such as changing the exhaust or air filter, the bike might run lean. This may result in more airflow than the stock parts and cause the motorcycle to run lean.
  • Idle Screw: When the idle screw isn’t correctly set or the ECU isn’t well set up, the throttle may stall.
  • Valves:  If the valves have a very tight clearance, it might cause the motorcycle RPM to drop.
  • Charcoal Canister: The motorcycle idle may become too low if the fuel tank charcoal canister gets clogged by dirt or old fuel, which will hinder fuel movement to the carburetor.

Motorcycle Idle Is Too High

A high motorcycle idle isn’t dangerous for the bike, but it isn’t ideal. However, if the biker notices that the bike is revving out, it should be shut off and the issue resolved. If these steps aren’t taken as soon as possible, it could blow up the motor. When the Harley-Davidson idle is too high, it needs to be adjusted using the idle knob.

When there is a louder than usual noise from the motor, the motorcycle idle is likely too high. Also, if the motorcyclist hears a loud grind sound when the bike is in gear, the idle level is high and needs to be adjusted. Here are some possible causes of a high idle.

  • Idle Screw: If the biker notices that their Harley-Davidson idle is too high, they should first check if their idle screw is well set and if the ECU is working correctly.
  • Oil Temperature And Water Temperature Sensor: If the oil or water temperature sensor is faulty, the motorcycle idle will become too high.
  • Throttle Valve: It is essential always to check if the throttle valves are syncing well. An improperly synced throttle valve causes a motorcycle idle to become high.
  • Throttle Position Sensor: A motorcycle idle can become too high if the throttle position sensor is not adjusted correctly.
  • Throttle Cable: A jammed throttle cable will not allow the valves to close properly, which will result in a high idle.
  • Intake Rubber Hose: Bike owners need to leak the intake rubber hose, which is between the throttle valve housing and the cylinder head.

How To Adjust Idle On Fuel Injected Harley Davidson?

A fuel injector Harley-Davidson bike will often come with a small knob that sticks out of the engine compartment on the left or right side of the bike. This small knob is used to adjust the idle if the motorcycle runs on a fuel injection system. The following paragraph will take a step-by-step approach to explain how to change idle on fuel injected Harley-Davidson.

How To Adjust Idle On Fuel Injected Harley Davidson

Step By Step Tips To Adjust Fuel Injected Harley Davidson:

Step 1: Identify The Motorcycle RPM

The ideal idle speed for the bike is listed in the user manual. The ideal RPM for most bikes is usually 700-1000 RPM. Some bikes also have tachometers to monitor the RPM when the motorcycle comes on. The tachometer helps the user check if the RPM is within the recommended range. If the bike doesn’t have a tachometer, the bike owner can use their ear and touch organs to determine the RPM. When the motorcycle is idle, the engine’s sound will be a low buzz.

Step 2: Locate The Carburetor

The motorcycle user manual will typically include a diagram of the motorcycle. With the manual, one can quickly locate the carburetor. The carburetor is a large metal part with a circular port on the side and a metal component. The location of the carburetor differs from bike to bike. The carburetor regulates the idle speed through a small crew, which is called the idle screw. The idle screw will control how much gas goes into the engine when the biker isn’t throttling.

Step 3: Locate The Idle Screw

The float bowl is a small gas tank that sits on the bottom of the carburetor. The bike owner should look around the float bowl for a screw connected to the coil. On some bikes, the coil may rest vertically on the carburetor but may rest horizontally on other bikes. The idle screw is usually on the left or right of the bike. However, on fuel-injected motorcycles, bike owners will see a knob sticking out of the side of the bike. The knob can get turned clockwise or anti-clockwise to adjust the idle speed.

Step 4: Remove Trim That  Block Access To the Screw

Sometimes, a piece of trim or panel may block the motorcyclist from adjusting the idle screw. If this happens, the biker will have to remove some bike parts to access the idle screw. The panel is easily removed by using a screw to remove the bolts or screws holding the panel in place.

Step 5: Turn The Motorcycle On And Wait For Three Minutes For The Engine To Level Out

When the biker turns on the engine, they have to wait for at least three minutes to level out and reach a stable temperature and speed. While it is possible to adjust the idle screw when the bike is off, it is better to do it when the bike is on. Adjusting the idle screw when the bike is on will help the engine adjust to the change slowly while there’s gas running through the engine.

It is essential to note the temperature when adjusting the idle screw. If the temperature is below 4 degrees, the bike should run for 10-15 minutes.

Step 6: Check The Idle RPM On The Tachometer

Motorcycle owners can look at their tachometer gauge while the bike is on to see if the RPM is at acceptable levels. If the RPM isn’t at the proper ranges, the biker must determine whether to lower or increase the idle speed.

Step 7: Tighten The Screw Clockwise To Increase Idle Speed

If the biker determines that the idle speed is too low, a Phillip head screwdriver should be used to turn the screw clockwise. If the coil is vertical and the screw is at the bottom, the biker should turn the screw anti-clockwise. The screw must get turned 3-5 times if the RPM increases dramatically. Also, if the screw is turned counterclockwise, the RPM will decrease.

Step 8: Inspect The Tachometer

The needle of the tachometer should show the change made to the screw.  If the tachometer falls within the recommended range, there is no need to make additional adjustments.

Step 9: Get On The Bike And Release The Brakes

After adjusting the screw, the biker should get on the bike and release the brake and let it run idle for 10-15 feet. Doing this will allow the biker to decide if the idle speed is appropriate or not. Finally, it is good practice for bikers to maintain their motorcycles regularly. A suitable Harley transmission fluid will not only lubricate the movable parts but also improve hydraulic pressure to make the internal parts work better.


As long as a Harley-Davidson bike gets ridden often, there is a high chance that the motorcyclist will experience problems with the idle. Knowing How To Adjust Idle On Fuel Injected Harley Davidson ensures that the bike’s speed stays at the recommended range.

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