You are getting ready for a ride down your favorite trail. You start the ATV, and you hear it idling higher than normal. What could be causing it, and how do you fix it?
There are many reasons an ATV may be idling high. Among these reasons are a carburetor leak, throttle cable placement, idle screw setting, clogged pilot jet, and many more. An ATV idling high should not be left unresolved. Allowing an ATV to idle too high could lead to premature wear and tear.
A higher than normal idle does not mean that you have to put an end to your day on the trails. This article will explain the reasons your ATV may be idling high and what you can do to fix it.
The carburetor is what supplies the air and fuel mixture to the engine to keep it running. If there is an issue with the carburetor, your ATV engine may be idling at a higher than normal rate.
The exact speed your ATV should idle at will depend on its age, make, and model. Newer ATVs idle somewhere between 1200 and 1700 RPMs. Check your owner’s manual to learn the exact idle speed your ATV should be at. If the ATV is idling high, it is likely related to an issue with the carburetor.
If the seal between the carburetor and the engine is compromised, it may be allowing extra air into the fuel mixture. This “lean” mixture can damage the engine as well as make it idle higher. A lean fuel mixture will also make for a jerkier ride than normal.
Inspect the intake system for any visible issues or damages. If there are no visible issues with the intake system, use a vacuum tester to inspect the integrity of the connections.
If you still have not located the problem, inspect the manifold and carburetor for visible problems. Ensure the vacuum sensors are not damaged. Spray water over the manifold and carburetor. If you hear the water getting sucked into the engine or the idle changes, there is probably a vacuum leak. Replace any tubes and connectors that are leaking air.
This test can be completed with carburetor cleaner as well—however, exercise caution when doing this. Carburetor cleaner is highly flammable and if it touches a surface hot enough, it could ignite.
Clogged Pilot Jet
The pilot jet is what draws fuel into the engine when idle. If the pilot jet is clogged, not enough fuel will be mixed with the air being sent through. Like a vacuum leak, this will result in a lean fuel mixture and a high idle.
The simple solution to this problem is to clean the carburetor’s pilot jets. Because pilot jets are so small, it may be difficult to find a tool small enough for the job. While you could take it to a mechanic to get the work done, there is one trick you can try yourself: using a bread tie!
Watch this quick video to see how to make your carburetor pilot jet cleaning tool!
Cleaning your pilot jet will not require any special tools or training. All you need is something small enough (such as a bread tie) to push out the fuel clog.
Make your bread tie into a cleaning tool, then run it through the pilot jets, reassemble the carburetor, and start up the ATV. If it continues to idle high, there may be another issue causing the idling. On the bright side, your pilot jets are now clean!
While many things could be wrong with the carburetor itself causing a high idle, it may be caused by the idle settings as well. There are two parts of the carburetor that allow you to adjust your ATV idle settings. These are the choke (throttle cable) or the idle screw.
Throttle Cable (Choke) Problems
According to an employee at Kolar Tire & Auto in Helena, MT, if the choke is stuck, it could be allowing extra air into the fuel mixture. As we already know, too much air in the engine results in a lean fuel mixture and a high idle.
Unstick the throttle cable by lubricating it with penetrating oil. Once covered with lubricant, use a pair of pliers to move the cable up and down. Eventually, the throttle should break free and move properly on its own. Apply another layer of lubricant for good measure.
Ensure the throttle cable is set correctly. If the carburetor’s side plunger is lifted off the idle screw, it could be letting too much air in. When set correctly, the carburetor’s side plunger will sit on the idle screw.
The idle screw is what determines how much air enters the fuel mixture. If you have altered the position of this screw, it may be letting too much air in. Verify the correct position of the screw by reading your ATV’s owner’s manual. Reset the screw to the correct position.
The problems described above are only some of the problems that may result in a high idle. Other reasons may be beyond your control.
The first reason your ATV engine may be idling high is a temperature change. When the weather is warm, fuel is easily vaporized and the engine does not have to do much extra work. However, when the temperature drops to cooler levels, the fuel may thicken. This thicker fuel forces the engine to work harder to pump it, thus resulting in higher idles. Because of this factor, you may want to wait until warmer weather begins before your try to diagnose your high idling problem.
Additionally, some ATVs simply idle higher when they first start. Let the ATV run for a few minutes; eventually, the RPMs will “settle down” to normal levels. If your ATV continues to idle high, search for the problems described above.
Some other reasons your ATV may be idling high are a dirty air filter or low-quality fuel. Never leave fuel in the ATV tank for more than a month or two. If you do, the fuel may “spoil” and damage the engine. Routine maintenance, such as cleaning the air filter, can also help prevent your ATV from idling high.