How to adjust (correctly) the accelerator of your motorcycle

In my years of career as a technical trainer, when I had to evaluate the experience and practical skills of a professional mechanic, this question was one of my favorites: "Could you explain how you set the accelerator cable adjustment?"

The majority of answers were similar, accompanied by a mechanic smile, which thought "this is going to be easy", and proceeded with the explanation: the acceleration cable is tense and then the return, until both do not have practically Game and release, the fist returns to its initial position. Then we went to the motorcycle in question, where the technician had to perform the operation. In a couple of minutes the adjustment was finished, as described above.

Experience is a degree

What came next was, in many cases, embarrassing, especially for the most experienced types. They were made to extract the air filter and accelerate thoroughly. Before his surprise, the throttle butterfly did not open much more than half of his route, so a motorcycle with said adjustment will not correctly accelerate and will never reach its maximum range of power and speed. What had failed?

Something as simple as the presumption that the experience gives. As we perform an operation many times, always with the same result, our brain tends to believe that every time we perform this operation, the result will be the same. This, which is an ancestral survival mechanism, often moves us away from the creative mental state that every mechanic should keep in mind when repairing, adjusting or diagnosing a motorcycle component: we must not give anything of course.

The importance of specifications

Generally, the workshop manual is designed to avoid these errors, provided we commit ourselves to follow it step by step, without skipping (assumption) none of them.

If we check, for example, the necessary steps to perform this process in a Harley-Davidson model (although they are valid for virtually any motorcycle with mechanical accelerator), we will see how simple it results and that at the same time it is practically impossible to make an error like the mentioned above.

Hands to work

1. The first step is to verify and perform the correct lubrication of the cables. If they are not well lubricated, the operation will be erratic, especially when reducing gas.

2. Then, the fist friction screw is completely loosen (it serves to make it more or less soft).

3. The locking nuts of both cables are loosen, and they proceed to the fullest.

4. This step that follows is where the adjustment error is usually made, as it is not done: we continue to put the direction straight, with the wheel looking forward. At this point, we open the fist to the maximum (WOT or “Wide Open Throttle”) and we keep it in this way, while we tension the accelerator cable until the accelerator cam touches with the cap of the carburetor.

We proceed to tighten the throttle cable lock nut and then, only then, we release the fist of the gas.

5. In the next step, we turn the handlebar totally to the right and tense the return cable until the cover touches slightly with the spring located at its end. We squeeze the lock nut.

6. The last step serves to verify that everything works correctly. The fist of the gas is opened and closed in its entirety, at the same time that we turn the handlebar in different directions. The operation must be soft and when you release the fist, it must quickly return to its initial position. We can already slightly tightened the friction screw, to our personal liking, without the return of the fist.

Conclusions

We can see that there are only 6 simple steps to correctly adjust one of the most important parts of the motorcycle, where the driver interacts directly with the power control of the machine.

Step number 4 guarantees that the maximum fist opening will coincide with the maximum opening of the throttle butterfly, provided that, of course, there is no budget that this already happens.

In fact, my recommendation would be that you perform this check of step 4 on your own motorcycle. Is it well adjusted? Bets are admitted ...

Frank Burguera

#mecanicaharley