Throttle Cable Slack: The Complete Guide

Throttle cable slack

You should check the slack on the throttle cable often. At least once in a while. Both the throttle cable and the clutch cable for that matter on your motorcycle.

But what exactly is a throttle cable slack? Why is it important?

Let’s discuss them in detail in this post. Starting with:

  • What is throttle cable slack
  • How much slack is necessary
  • Is the slack good
  • How to measure the slack
  • How to adjust the slack
  • How often should you check

And a bit more. So, let’s dig in.

Throttle cable slack – what is it?

Locknut in the motorcycle throttle cable

Throttle cable slack measures the free play on the motorcycle throttle.

Put simply, slack is how much you need to roll the throttle before the throttle starts accelerating or decelerating.

In other words, the slack is the free play you feel on the throttle.

More the slack on the cable, more will be the free play on the throttle.

One way to check how much slack the throttle cable has is by rolling the throttle and measuring the twist it takes before you start feeling the tension.

When there is slack, the free play ensures you don’t feel the tension for some time. But after rolling more, you start to feel the throttle tension. And the acceleration starting.

If this measurement confuses you, leave it. We have a detailed section below on how to measure the throttle cable free play.

For now, let’s look into whether the slack is good or bad.

How much slack should a throttle cable have?

Locknut in the motorcycle throttle cable

So what’s the ideal throttle cable slack on motorcycles?

Most manufacturers recommend a slack of 2 to 3 mm on throttle cables.

Anything more than that, the throttle cable feels loosened. The free play is too much. There will be delay in the throttle response.

And less than that, the throttle cable is too tight. Even with the smallest twist, there will be a throttle response. You need some free play.

Then again, the free play should not be too much That would mean a loosened throttle cable.

That’s why a 2mm to 3mm free play is the sweet spot.

Less than that, the cable is too tight and the throttle responds for even the smallest of twists.

More than that, the cable is loosened and the throttle response is delayed.

Is the slack good or bad?

Motorcycle with 2 throttle cables

A small amount of slack (free play of 2 to 3 mm) is a good thing.

The motorcycle throttle needs some slack. That’s why a 2 to 3 mm of free play is recommended for the throttle cable.

But too much slack is a bad thing of course.

If the free play exceeds the desired 3mm range, there can be problems in the throttle response as well as in the motorcycle performance.

What are those problems? Let’s discuss that.

What happens when the throttle cable is loose?

Loosened throttle cable on motorcycle

If the throttle cable is loose, i.e., has too much slack, these are the main problems it will cause:

  • Slow throttle response: There will be a delay between the time you roll the motorcycle throttle and its response in the carburetor and the throttle system. You need to wait a few seconds after rolling the throttle to see its effects.
  • Delay in acceleration: The slow throttle response leads to a delay in motorcycle acceleration. This can lead to the rider twisting the throttle more. Going overboard with the acceleration.
  • Poor pickup: The motorcycle won’t pick up speed easily. This is of course because the motorcycle won’t accelerate fast. So whenever the throttle cable is loosened in a motorcycle, expect the motorcycle to have speed pick-up issues.
  • Power lags: Power lags happen when the motorcycle is running at high speeds. Power lags are basically the motorcycle not accelerating despite throttling up. The motorcycle won’t power up fast and there is a lag which is pronounced at higher speeds.

There are a few other consequences too. Here is a detailed post on the effects and symptoms of a loosened throttle cable.

How to measure the slack on the throttle cable

Motorcycle throttle

The next question that comes to our mind is – how do you know if the slack is too much? How do you measure the slack?

Put simply, slack is the amount of twist on the throttle from rest to its starting tension point.

But if you want the exact measurement, we can do that as well.

To check the slack on the throttle cable, here are the steps:

  • Roll the throttle forward until it stops. You can no more roll forward.
  • Now, gently roll back the throttle until you feel the tension. (Only when the tension starts in the throttle cable, will there be acceleration/deceleration.)
  • The distance from the stop position to the tension position is the throttle free-play.
  • You can also make use of the parting line and the horizontal grip lines on the throttle to measure the free-play easily.

How to take slack out of the throttle cable?

Motorcycle throttle cable adjustment

To take slack out of the throttle cable, you need to tighten the throttle cable.

How do you do that? How do you tighten the throttle cable?

In simple steps:

  • Locate the locknut on the throttle cable first
  • Slide the protective cover
  • Tighten the locknut with a spanner
  • Leave a slack of 2-3 mm
  • The throttle cable is now adjusted

That’s the gist.

But if you want it step-by-step, here is our detailed guide on throttle cable adjustment.

How often should you inspect the throttle cable?

Motorcycle throttle

Inspect and adjust the throttle cable every 5000 miles of motorcycle distance covered.

Apart from this regular maintenance, check the throttle cable every time you go for a long ride. Especially if it is going to be off-road.

You might also have to replace the throttle cable sometimes. While adjusting the free play works most of the time, sometimes replacing might be the only option.

That’s why it is recommended to carry spare cables (throttle cable as well as clutch cable) whenever you are going for a long ride.