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How to Adjust Carburetor on Johnson Outboard

how to adjust carburetor on johnson outboard

During your fishing trip, you are experiencing your carburetor acting up pretty rough. And at times, they are pretty annoying because they scare the fish away.

So, how to adjust carburetor on Johnson Outboard?

To adjust carburetor on Johnson Outboard, find a small knob at the side of the tiller. Turn the knob clockwise to the lowest setting and make the engine idle. Turn the throttle towards low. Now turn the “choke” knob towards the low setting. The carburetor takes 30-40 sec. To catch up to the setting.

That is the summarized method for adjusting the Johnson outboard carburetor. And in the next sections of the article, I’ll explain the method more. So that you can understand and follow better.

Keep on reading to find out!

Adjust Johnson Outboard Carburetor: Step By Step

A 6 HP Johnson outboard motor’s slow speed should be adjusted on a regular basis.

It helps to maintain the engine’s efficiency and improve fuel economy. Near the front of the outboard motor, a carburetor is where you’ll find the slow-speed idle. Besides, there are few Johnson outboard problems you should look out for.

It’s the Adjustment screw, commonly known as the low-speed needle. You can save time and money by quickly adjusting the slow-speed idle adjustment screw with a screwdriver.

Keep reading below –

Step 1 of 4: Adjust the Slow Speed Idle

With a screwdriver, rotate the slow-speed idle adjustment screw counterclockwise. Until it is seated, be careful not to over tighten the screw.

Step 2 of 4: Turn the Slow Speed Screw to Starting Position

With a screwdriver, rotate the slow-speed screw counterclockwise for 1 1/2 turns. This will obtain the starting position for additional adjustment.

Step 3 of 4: Warm Up the Boat

Start the outboard motor and give it about five minutes to warm up. Set the throttle to a slow trolling speed.

Step 4 of 4: Adjust the Carburetor and Catch Up

Turn the screw counterclockwise 1/4 move at a time until the motor starts to stall. At this point turn the screw clockwise 1/4 turn. It’ll reach the ideal position for the 6 HP motor.

How to Adjust Carburetor for 40 HP Johnson Outboard

Adjust Carburetor for 40-HP

There aren’t many modifications you can perform to Johnson’s 40-horsepower carburetor.

With the exception of the float tank and carburetor lid, which are removable. It is made of a single piece and is unitized in construction. A detachable jet installed in the float compartment is used to measure the fuel.

The mixture is pre-set in this single-barrel, float-feed style carburetor. A screw that is attached to the side of the carburetor lid and secured in place by a lock nut. It allows you to change the idle speed of the motor.

Step By Step Guide to Adjust Carburetor for 40-HP

It’s not so difficult to adjust the carburetor of a 40-horsepower Johnson Outboard.

Follow the steps below to adjust the carburetor –

First, keep these tools near your reach –

  • Digital shop tachometer
  • Flushing attachment
  • Garden hose
  • Small adjustable wrench
  • Standard slotted screwdriver

Step 1 of 3: Heat Up the Outboard

The motor cover can be removed by turning the cover locking handle upward. Connect the alligator clip of an electronic shop gauge to the first spark plug of the engine.

Start the engine, and let it run until it reaches the desired temperature. While doing this, look out for common Johnson shift linkage adjustment problems.

Step 2 of 3: Reach Idle Speed

Put the motor in forwarding gear. For this motor, the best idle speed range is within 800 to 900 rpm. With the ideal idle occurring close to the middle of that range.

Step 3 of 3: Adjust Carburetor

Avoid touching hot or moving parts. Use a little angle grinder adjustable wrench to loosen the lock nut if an adjustment is required. It’s on the idle speed screw, use a normal slotted screwdriver to turn the screw clockwise. Idling speed can be increased by turning this clockwise or decreased by turning it counterclockwise.

How to Adjust Evinrude Outboard Carburetor

Adjust Evinrude Outboard Carburetor

The heading may have surprised you if you’re new to the outboard word. Is Evinrude the same as Johnson? Yes, Evinrude bought Johnson sometime after 2007.

Make adjustments to the Evinrude carburetor while the boat is moving and the engine is running.

While you make the modifications, a second boater must steer and operate the boat. These modifications put you in close contact with the engine’s moving parts, which could be dangerous. Only make the modifications in calm water and on clear days.

3 Easy Steps to Adjust Carburetor on Evinrude/Johnson Outboard

Here are the three steps to adjusting the carburetor of your outboard –

Step 1 of 3: Run the Boat Forward AT Half-Speed

Set the two-cycle setting on the shop speedometer. Connect the primary lead of the ignition coil to the speedometer. Turn on the motor and let it run in “Forward” at half-speed. Keep it running until it reaches the proper working temperature.

Step 2 of 3: Set the Throttle to Idle

Remember to set the throttle to “Idle” mode. Turn the idle speed regulator screw using a screwdriver. Until the shop tachometer designate that the engine is running in the proper rpm range.

The ideal range is between 1,000 and 1,300 rpm. The idle speed adjustment screw should be turned at least once every fifteen seconds.

Step 3 of 3: Adjust the Carburetor

Running the engine at various throttle settings lets you verify the accuracy of the speed adjustment. When the throttle is advanced past two-thirds throttle, the engine will “bog down”.

If it is running too rich, the idle speed will be greater than the desired idle speed. As the idle speed adjustment screw also regulates the mixture, change the idle speed once more. Then repeat the test until the motor no longer “stumbles” under sudden acceleration.

Carburetor Adjustment for High Speed

With the appropriate size screwdriver, carefully spin one of the H/S needles at full throttle. Wait a little period for the engine to react, then repeat twisting.

The engine will eventually start to fail at some time. Back that needle valve out by about a quarter turn at that point. Repeat the process at the other High Speed needle valve now.

You will eventually come across the smoothest high speed setting during that 1/4 turn out. When both high-speed needle valves are properly set, you can lift the center adjustment lever. Lift it to the high ridge, holding it raised until the tip is facing the engine. And then lowering it into its correct position.


15 HP Outboard Faster

How Can I Make My 15 HP Outboard Faster?

On the Johnson outboard, replace the propeller. Choose a propeller with a higher pitch. If you want to achieve the top speed out of your motor. The motor’s acceleration will be slowed by this. But the top speed as a whole will rise. Reduce the pitch if you want to accelerate more quickly.

How To Stabilize The Low Idle Speed On A Johnson Outboard Motor?

It’s actually quite easy to adjust the low idle speed on the johnson outboard motor. 1 1/8 counterclockwise twists on the screw. Start the engine of your outboard. Take note of the tachometer’s reading. To increase or reduce speed, turn the screw in a clockwise or counterclockwise direction.

How Do You Adjust An Outboard Carburetor?

An outboard carburetor’s idle stabilizer can be found below the carburetor. To make the engine idle slow down. Turn the idle adjustment 1/4 turn clockwise with a tiny adjustable wrench or screwdriver. To ensure a smooth idling of the engine, crank the knob counterclockwise in 1/8 turn.

How often should I adjust the carburetor ?

It is recommended to adjust the carburetor on your Johnson Outboard annually or as per the manufacturer’s recommendations in the owner’s manual. However, you may need to adjust it more frequently if you notice any issues with engine performance or fuel economy.

What are some signs that my Johnson Outboard carburetor needs adjustment?

Some signs that your Johnson Outboard carburetor may need adjustment include rough idle, difficulty starting the engine, poor fuel economy, and engine stalling or misfiring.

Can I adjust the carburetor on  myself, or do I need to take it to a professional?

If you have some basic mechanical knowledge and tools, you can adjust the carburetor on your Johnson Outboard yourself. However, if you are unsure or inexperienced, it is recommended to take it to a professional mechanic or service center.

Is it necessary to warm up the engine before adjusting the carburetor ?

Yes, it is important to warm up the engine before adjusting the carburetor on a Johnson Outboard.adjusting the carburetor

This ensures that the engine is at the optimal temperature for adjustment and provides accurate readings.

What is the purpose of adjusting the carburetor ?

The main purpose of adjusting the carburetor on a Johnson Outboard is to optimize engine performance and fuel economy.

A properly adjusted carburetor ensures that the engine runs smoothly, idles at the correct speed, and provides optimal power output.

How do I know if I have adjusted the carburetor correctly ?

To know if you have adjusted the carburetor correctly on your Johnson Outboard, you should observe the engine’s performance and fuel economy.

If the engine runs smoothly, idles at the correct speed, and provides optimal power output, then the carburetor is adjusted correctly.

What should I do if I am still experiencing issues  after adjusting the carburetor?

If you are still experiencing issues with your Johnson Outboard after adjusting the carburetor, it may indicate other underlying problems with the engine.

In such cases, it is recommended to take the outboard to a professional mechanic or service center for diagnosis and repair.


That was everything on how to adjust carburetor on johnson outboard. Now you can take your outboard out for fishing. And it won’t make any loud noise that drives the fish away.

Did the article help you to adjust the carburetor? Let me know what helped.

Until then, happy fishing and sailing!

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