In this article from
Trialworld Garage
we show you some basic notes for the tuning of the carburetor.
In the
first installment of this report
, we analyze the parts that make up the carburetor and their respective functions. It is essential to understand this first part well in order to delve into the one we are going to address in the following lines; Only in this way will we be able to understand how to improve and adapt the performance of the engine to each circumstance or terrain.
We start from the premise that there is no universal standard to achieve the desired result. However, before getting down to work, it is important to keep an eye on some aspects that directly influence the result we are looking for and do not depend on the carburetor. Therefore, the carburetion must be the icing on the cake of the set-up. Let’s go over what elements we need to keep an eye on beforehand:
First of all we must
check the condition of the air filter
, spark plug and preferably the gasoline must have been mixed recently. For the tuning we will use suitable tools, avoiding pliers, as they could damage the components.
It is important to remember that the work will be valid for the specific time and place. The sea level is not the same as the mountain, nor the summer is the same as the winter, so we will probably need to keep adjusting if we always want to get the most out of our mechanics.
CARBURETION ON THE TRIAL BIKE
The standard bikes are well tuned, although obviously with parameters tested at the place of manufacture. In spite of this, our recommendation when using the bike for the first time is to adjust the low gum and the needle. The reason for this is that high gum only takes full effect when the throttle is fully open.
The low circuit is made up of the low gum and the air screw (the small external one next to the idle); Between them, they regulate the richness of the gasoline-air mixture that reaches the carburetor at low revs. Of these two, the only one that can be externally regulated is that of the air. By loosening the screw we are allowing more air to enter and the mixture will be leaner. To achieve the desired result, it may be necessary to place a low-grade gum with a larger diameter to increase gasoline traffic.
All the necessary accessories are available in this
motor and electric section of the Trialworld Store
.
Keihin Low Chewing Gum Refills
Keihin High Gum Refills
Keihin carburetor for trial bikes
Dell ́Orto carburetor for trial bikes
Approximately, it is usual for the air screw to be loosened for two turns (we start from the screw tightened to the maximum).
The key is to test little by little and keep an eye on the condition of the rest of the components that affect the carburetion.
In order not to depend on screwdrivers and to be more precise in carburetion, both the Keihin carburetor air screw and the Keihin idle screw
are marketed in a format that allows you to adjust the carburetion of the motorcycle by hand.
CARBURETING THE TRIAL BIKE WELL
With the engine hot, we will put it in neutral and increase the idle until the pistones are continuous and homogeneous; Then loosen the air screw a quarter of a turn, give a blow of gas, wait a few seconds and repeat the operation. We will see that the response is faster and faster, as a result of the impoverishment of the mixture.
However, there comes a time when the set speed accelerates irregularly and the bike responds with a more metallic noise due to an excessive impoverishment of the mixture.
At this point, we must do the reverse operation, that is, tighten the air screw until the best balance is achieved.
If we notice some small hiccups in the drop in revs after releasing the accelerator and these do not disappear no matter how much we loosen the air screw, we will proceed to replace the low gum with another of smaller diameter.
From this point on, all that’s left to do is test and adjust the area. It is recommended that you carry a small screwdriver with you to fine-tune it little by little.
BEST RESULTS
These are basic notions of carburetion that will allow each user to have greater autonomy on their motorcycle, identifying small imbalances and optimizing performance. However, carburetion is much more complicated than all this; The chimney-bell set or the high chewing gum can also come into play, but the operation can be more complicated.
Our recommendation is that, if you do not achieve the desired performance with the above tips, you should put yourself in the hands of experts or ask yourself if the problem may be of another nature, for example electrical.
TRIAL BIKE SPARE PARTS
If you need chewing gum for your carburetor or
spare parts for your trial bike
, you can find them at
the Trialworld Store.
You will also be able to find everything you need for
the equipment of the trial rider
and
trial outlet
.
