How to Adjust Harley Throttle Cables

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How To Adjust Harley Throttle Cables

Are you a Harley-Davidson biker in need of adjusting your throttle cables, but you don’t know how to? If yes, then this is definitely the right place for you to be.

Adjusting Harley throttle cables is a pretty easy process, as long as you know the right instructions. To adjust the throttle cables on your Harley-Davidson bike, you will need to check the initial throttle cable slack, find the adjusters, make changes at the barrel adjuster, make larger changes at the adjuster in the engine bay, verify that the throttle cable isn’t too tight, and check if the cable is kinked or pinched.

Once you know to properly inspect and adjust the throttle cables, you will be in a prime position to replace them.

In this guide, you will get to know all about throttle cables, how to adjust Harley throttle cables, how to check the condition of your throttle cable, and more. Stick around to get all the answers that you are looking for.

No More Malfunctioning Throttle

If you’re a Harley-Davidson biker who loves riding, it is important that you carry out a neglected yet essential maintenance task – inspect and adjust the throttle cable. The throttle cable will connect your body and mind to the heart of your bike. This makes it an essential link. Damaged, worn, misadjusted, or corroded throttle cables can easily lead to dangerous riding conditions and poor engine performance.  

Harley-Davidson Mirror Throttle

A throttle cable is a critical component to the functioning of your Harley-Davidson bike’s functioning. However, it is often overlooked. If you know how to adjust Harley throttle cable, you will get better control and performance out of your bike.

Most service manuals suggest that you should check throttle operation after every 2.5 hours of operation. Along with the generic recommendations, engine performance can also be a major indicator of cable issues. Poor full-throttle operation could be a sign that the throttle cable has got too much slack. An engine that is difficult to control or features an erratic idle could indicate that there isn’t enough throttle cable slack.

Check the Condition of Your Bike’s Throttle Cable

The throttle cable must be inspected visually for any damage. Kinks, cracks, corrosion, and severely worn areas due to rubbing will be a cause of concern. You need to systematically inspect the throttle cable from the throttle grip to the carburetor or throttle body as best as visually possible. Try to visually follow the routing of the throttle cable and inspect for damage and wear regularly. 

Check cable free play

Throttle cable free play is usually checked by measuring how much throttle grip movement there is relative to a fixed point on the throttle cable housing. Most models specify 2-3mm of throttle grip free play. It can be checked easily by referencing a predominant feature on the throttle grip or by marking it with a marker and then measuring the amount of motion relative to the housing using a scale, ruler, or caliper.

You can easily measure the throttle cable free play by marking the grip in accordance with a reference point like the split in the throttle cable housing. Further, you should twist the throttle until you feel resistance and then measure the amount of movement.

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Check the throttle return

Most throttle systems designed for motorcycle applications are designed to fail closed in case the throttle cables break or if the rider loses control of the machine. The return spring pressure can be inadequate in case the throttle cables are sticky or if the throttle grip is binding on accessories like handguard mounts.

Check the throttle operation by opening the throttle fully and letting go. Confirm that the throttle returns completely to the closed position quickly and easily. Check throttle return with the handlebars to the right, to the left, centered, and halfway between center and full stop on each side. If the throttle doesn’t completely return, then the cable might be binding, frayed, incorrectly, or corroded.

With your Harley-Davidson motorcycle off, you should twist the throttle open to the stop and let go. You should ensure that the throttle returns to the closed position easily and quickly. 

How to Adjust Harley Throttle Cable

Most modern Harley-Davidson bikes that have throttle bodies and carburetors actually utilize two throttle cables, which are aptly identified as accelerator and decelerator cables. Older carbureted machines feature only one throttle cable. Depending on the type of Harley-Davidson bike you’re riding, the adjustment process might differ slightly from the outline mentioned here.

The number of adjustment locations will differ depending on the machine in question. Some bikers have adjustment points at the throttle body/carburetor or at the throttle cable housing, whereas others feature a single adjustment point on the throttle cable housing. On bikes with multiple adjustment points, minor adjustments can be made at the throttle cable housing. Meanwhile, the adjustments are taken care of on the throttle body or carburetor. 

Dual cable adjustment

The first step to adjusting the throttle cable on your Harley-Davidson bike will be to remove any necessary dust covers and identify the accelerator and decelerator cables. The accelerator cable will go into tension after the throttle is twisted open, while the decelerator cable will be put in tension once the throttle is closed. Each cable can be identified visually by looking at the housing design or by making adjustments and determining what is affected.

To adjust the throttle cable, the locknuts should be loosened, and the cable adjusters should be turned in to slacken them or turned out to tension them. It can be easily accomplished manually or by using an appropriately sized wrench.

Commonly, the decelerator cable should be adjusted first. The decelerator cable tension is usually set such that there is no play once the throttle grip is completely closed. Once the decelerator cable is set, the accelerator cable can be adjusted. The accelerator cable tension is normally set such that 2-3mm of free play is present in the throttle grip. Once the correct tension is applied, the lock nuts should be snugged and the dust covers must be slid back over the adjusters.

Single cable adjustment

Single-throttle cable adjustment is rather straightforward. Any dust covers that are protecting the cable adjuster must be removed first. Next up, the locknut needs to be loosened. The cable adjuster can be adjusted in or out such that the throttle grip has the correct amount of free play (usually 2-3mm). Once it is complete, the locknut can be snugged and the dust cover can be reinstalled.

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Checks to do after adjustment

Upon completion of the cable adjustments, the system needs to be checked as outlined in the throttle return section. Once you have confirmed that the throttle return functions properly in the handlebar positions, the engine must be started.

With the engine idling and in neutral, you should rotate the handlebars from stop to stop and listen for potential changes in idle behavior. The increases or decreases in idle speed might suggest that the throttle cable is binding, either due to cable routing or tight spots.

How to Replace the Throttle Cable

In case the throttle cable on your Harley-Davidson bike warrants replacement, cable replacement can be accomplished with ease. Selecting and sourcing a new throttle cable will be equally important as carrying out the work. Sourcing OEM parts from a dealer can often lead to overpaying. This is why many bikers turn to the aftermarket and online platforms. However, it is important that you be careful not to sacrifice quality for cost.

There are many OEMs that offer throttle cables at rather affordable prices. As the throttle cables are made by the suppliers, the quality and specifications of these throttle cables will suit your needs perfectly. You need to ensure that you remove the necessary components to access the throttle cable and throttle body or carburetor.

Once you have removed the necessary components, replacing the throttle cable will be rather straightforward. Most bikes come with a dual throttle cable, so the following method will involve replacing the dual adjustment cables. The steps to replace a single throttle cable are almost identical.

Start off by loosening the throttle cable adjusters on the throttle housing and then slackening the cables. Next up, you need to remove the fasteners that are holding the throttle cable housing together. Once removed from the handlebar, you should remove the throttle cable ends from the throttle cable housing pulley. Also, note the accelerator and decelerator cable positions before you remove them from the throttle housing pulley.

Remove the necessary covers from the throttle body or carburetor for gaining access to the throttle cable ends. Moreover, note the locations of the accelerator and decelerator cables before you remove them. Loosen the necessary adjusters and locknuts before removing the cable ends from the pulley.

On single-cable carbureted applications that feature round or oval slide carburetors, you need to unscrew the top cap of the carburetor where the throttle cable is entering the slide. You must compress the return spring and then carefully remove the necessary hardware securing the cable end to the slide. Once removed, you can easily loosen the cable and remove it from the carburetor cap.

Next up, you should prepare the new throttle cables by applying cable lube to both ends of the throttle cable. Check the smoothness of the throttle cable by moving them back and forth before the installation. A cable luber is a wonderful tool to have. It will simply fix the end of the cable and allow the tube to flow through the inside of the cable.

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Once the old throttle cable is free on both ends, you should note how they have been routed.  After that, remove the cables and route the new cables in a similar fashion. In case the old cable routing is suspected, you can confirm with factory-prescribed cable routings in the service manual. Make sure that you are following the OEM routing when installing the new throttle cables.

Upon successful cable routing, you should start the reassembly process. Start off by installing the cable ends into the throttle body or carburetor and the throttle cable housing. Turn the cable adjusters on the throttle grip housing all the way in before turning each one of them one turn out.

Once you have done that, unless otherwise specified, you need to use the throttle body or carburetor adjustment features and take the majority of the slack out of the cables. You should refer to the tips outlined in the cable tension adjustment section above to properly tension the throttle cables. Once the cable tensions have been set, you should ensure that you check the functionality of the throttle return as prescribed.

Take the majority of the slack out of the cables at the carburetor adjustments or throttle body first, and fine-tune the adjustments at the throttle housing. Once the new throttle cables have been properly installed and the return checks are complete, you should finish the job by reinstalling any items that needed removal to gain access to the cable system. Once everything is reinstalled, you need to test the functionality of the system first with the engine off. After that, you should test the functionality with the engine idling for ensuring that there aren’t any abnormalities. 

FAQs

How to know if my throttle cable is loose?

Poor full-throttle operation could be a sign that the throttle cable in your bike has too much slack. An engine that is difficult to control or has an erratic idle is an indication that there isn’t enough throttle cable slack.

Should there be slack in the throttle cable of a bike?

Most motorcycle manufacturers recommend that there should be about 2 to 3 millimeters of throttle-free play. However, over time, the cables eventually stretch and settle into their housings and the biker ends up with more slack.

How to reset my Harley-Davidson throttle?

To reset the idle setting of the throttle, you should turn the ignition light on for 10 seconds and then off for 10 seconds, a total of 4 times. Remember not to start the engine. This will reset the original throttle position of your bike.

Why do Harley-Davidson bikes have two throttle cables?

Some carbs don’t feature a return spring, so they will require two cables. One cable is to open the throttle, while the other one is for closing the throttle.

How much play should a Harley-Davidson throttle have?

It is recommended that you should have around 2 to 3 mm of throttle-free play. But just to be on the safe side, you should check the owner’s manual.

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