Motorbike throttle

Whatever type of bike you ride, and wherever you ride it - on the road, dirt, or track - mastering throttle control is crucial. 

What your right hand does affects your bike’s suspension, that in turn changes your chassis geometry, altering the way your bike behaves. Get on or off the throttle at the wrong time, or in the wrong way, and that can have a massive effect; unsettling suspension and balance mid-corner, messing up turn-in points and exit.

Now, you can master your own control and technique as much as you like, but you also need to make sure the throttle itself does what you want it to, when you want it to do it.

As we know cables can stretch over time and when that happens there’s a delay between twisting your wrist and the fuel reaching your cylinders. That doesn’t sound like much, but that moment could come a fraction of a second after you needed it; corner ruined. 

The aim of the game is to get rid of that ‘free play’ in your throttle. Here’s how: 

Measuring Throttle Free Play:  

Most motorcycle manufacturers recommend between 2 to 3mm of throttle free play, but check in your owner’s handbook to be sure. 

With the throttle fully closed, make a note of the grip position. Slowly twist the throttle open until you start to feel the tension in the cable. The distance from the ‘closed’ position to the tension point is your free play 

(Tip: If you’re struggling to measure this, cut two small pieces of masking or insulating tape into points. Stick one piece to the grip and one to the switchgear pointing together. When you’ve twisted the throttle to feel the tension, measure between the two points.) 

Adjusting Throttle Free Play: 

If the free play isn't as it should be there are usually two places on the cable where adjustments can be made: up at the grip and down at the carb(s) or throttle body(ies). 

The barrel adjusters on the cables are for fine-tuning the free play, while the adjusters down by the carb(s) are for making larger adjustments. The adjusters effectively lengthen or shorten the cable outer, which in turn changes the length of the inner cable that’s doing the pulling. 

If your free play is out by a small amount, use the inline adjuster at the handlebars: simply loosen the locknut, and turn the barrel adjuster until the movement of the grip is in the specified range. 

If the adjuster at the grip is nearing the end of its range - so it’s only holding on with a few threads - or you can’t get the right free play, you’ll need to turn your attention to the adjuster at the carb/throttle body. These usually work the same, so follow the procedure outlined above to set the play. 

Once you’ve set the free play, turn your handlebars from lock to lock to make sure the cable doesn’t pull or catch. Start the engine and turn the bars lock to lock again and check that the idle doesn’t change. If it rises, check the cable routing, in case it’s catching anywhere, and recheck and adjust the free play if needed.

(Note: While 2 to 3mm is the usual recommended amount of play, some riders prefer less - so there’s zero delay between turning the throttle and power coming on. You can experiment with different free play amounts to find the setting that suits your riding style, but remember: if the throttle cable is set too tight, it can hold the throttle open, so be sure to check the throttle is returning fully and the bike is idling normally, before you head out riding.)

Adjusting Twin Pull Throttle Cables: 

If you see two cables coming out of your throttle, you have a push/pull throttle - one cable opens the throttle, the other one (along with a throttle return spring) closes it. 

First, figure out which one is the ‘accelerator’ and which is the ‘decelerator’ cable: the accelerator goes into tension when the throttle is opened, the decelerator is in tension when it’s closed. 

The adjusters are usually the same as a single cable, with a lock nut and barrel adjuster. 

Adjust the decelerator cable first. Tension is usually set so there is no play when the throttle grip is completely closed. Then set the accelerator cable tension to either the factory 2-3mm or to your preferred setting. 

If you want to go one step further and upgrade your throttle set-up, our range of Performance Twistgrips can help you get the feel and control you’re after - some can even be fine-tuned to suit your riding style or the conditions you're riding in. 

We also recommend upgrading to our Featherlight Throttle Cables, which are developed from the original factory-fitted lines, and are designed to give improved performance and feel, as well as adding durability and a smoother action. 

[Note: Your motorcycle’s service manual will tell you what adjustment is possible and the tools you’ll need for a job. If you’re not 100% confident doing any of the steps above yourself, consult a professional.]

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Phil Turner has been a motorcycle journalist for 20 years. A former mechanic, he worked as a staff writer and road tester for classic, modern and scooter titles, and edited Motorcycle Sport and Leisure magazine. He turned freelance in 2008 and is a regular contributor to specialist bike titles, both online and print. Phil has owned an eclectic mix of machines, including a Lambretta GP200, three air-head BMWs, a Honda CBF600 and a Royal Enfield Bullet.