Carburetor for a scooter - which one to choose, how to adjust

Adjusting the carburetor on a scooter (moped)

The functionality of the carburetor of a scooter (moped), as reported by the source of this article, prokarbyrator.ru, has factory settings. But since adjustment by the manufacturer is carried out under the conditions of the place of manufacture and differs from the place of operation, the owner of the scooter (moped) needs to adjust the carburetor.

Adjusting the carburetor on a scooter (moped)

For this purpose, all carburetors are equipped with an adjustment system. There are no factory settings for carburetor functionality that are set once and for all.

Instructions for adjusting the carburetor on a scooter

Due to the fact that there is no uniform setting for the operation of the carburetor permanently established by the manufacturer, the protection of the unit from making errors during on-site adjustment is weakened.

Correct adjustment can be made by performing the following sequential steps:

place the scooter on the folding stand;
warm up the engine;
we adjust the idle speed by rotating a special bolt (the speed should be minimal in number, but stable);
We provide freedom of access to the carburetor;
Let's start adjusting the composition of the combustible mixture;
to regulate the composition of the mixture, according to the manufacturer's instructions, each model has its own special bolt, so look at the instructions for the purchased scooter model;
We take into account that carburetor models of different designs differ in the direction of rotation of the bolt (for some models, when rotating clockwise, the mixture is enriched with gasoline, for other models it is the opposite);
We perform a sharp gas supply “full throttle” under load;
we look at the result of regulating the combustible mixture (choking or detonation of the engine is an indicator that the adjustment was performed incorrectly; if the engine “picks up” and a confident increase in speed occurs, then the adjustment was performed successfully);
We let off the gas sharply (if the engine does not stall and produces the set speed at idle, then the fuel mixture has been adjusted correctly).

For some models to operate effectively, it is necessary to adjust not only the fuel mixture, but also the carburetor needle.

Why adjust the carburetor?

Carburetor adjustment may be required in the following cases:

The spark plugs are serviceable, but do not work very well; their color has changed to black or yellowish.
The engine does not provide the required power
Scooter won't start
Fuel consumption has increased excessively.

All these problems in most cases are caused by an insufficiently enriched or, conversely, overly enriched mixture with oxygen, and they can be corrected by correctly adjusting the carburetor.

The settings, regardless of whether you have a 2t or 4t scooter, have three phases and are made as follows:

Idle speed adjustment
Setting the fuel level
Adjusting the quality of the mixture.

On some carburetor models there is no screw that adjusts the fuel quality, so you have to disassemble the carburetor to change the position of the needle.

The idle speed adjustment is carried out after the engine has warmed up: this takes no more than 15 minutes. For this purpose, the design provides an idle screw. It allows you to make the engine stable by selecting the desired idle speed. When the screw is tightened, the speed will increase, and when it is rotated counterclockwise, it will decrease.

It is important to adjust the quality of the mixture. If it is too lean, the scooter will ride with difficulty, the engine will noticeably lack power

If the mixture is too rich, the spark plugs will turn black and quickly fail. Fuel quality adjustment is usually carried out using a screw located on the carburetor body. To enrich it you need to turn it clockwise, to lean it counterclockwise. If there is no screw, the carburetor is opened, the locking ring on the needle moves up for a richer mixture, down for a leaner one.

Adjustments are made as follows:

Start the engine and warm it up for 10 minutes, after which you need to turn it off
The screw must be tightened clockwise until it stops, but without force.
After this, it is unscrewed counterclockwise 1.5 turns
The engine needs to be started and the screw turned an additional 1/3 turn in the same direction. Wait 2 minutes
As the speed increases, you need to unscrew the screw an additional ¼ turn and observe the reaction for about 2 minutes. If the speed does not drop, repeat the steps
If the speed begins to decrease, the screw must be turned clockwise by ¼ turn.

Ideally, the engine will operate exactly at 1.5-2 propeller revolutions, but its position depends on the quality of the fuel. In the case of a needle, the quality of the mixture will vary depending on the position of the needle locking ring. The disadvantage of such a carburetor is the small number of needle positions and the need to disassemble it each time to make adjustments.

You can adjust the fuel level in the chamber as follows:

Unscrew the drain screw
The phone is lifted up
You need to check the fuel level while the engine is running. The melting level is slightly below the skirt located on the float chamber cover
Most often, the level rises above normal and the carburetor overflows, so you need to adjust the float so that it fires earlier. To do this, the needle holder is usually bent. A lot of force is not required, only a few mm are needed.

Carburetor needle adjustment

When adjusting the operation of the carburetor, situations are possible when the adjustment is not limited to optimizing the combustible mixture. In this case, it is necessary to adjust the carburetor needle.

To do this, we perform the following set of actions:

move the needle one notch in one action;
We release the gas sharply, if the engine stalls, then raise the needle;
give full throttle, if there is no increase in speed, lower the needle.

Checking the result in action. Inspection of the combustion chamber spark plug.

Upon completion of the adjustment, you need to ride the scooter for 2-3 km. While stopping, inspect the part of the spark plug located in the combustion chamber. If the insulator has become dark in color (possibly blackened), then the combustible mixture is very rich, the carburetor needle must be lowered. If the indicated part of the candle is white, then the mixture is lean, the needle should be raised.

An indicator of the optimal combustible mixture and correct adjustment of the carburetor is the sandy or brick color of the combustion chamber spark plug insulator.

Purpose and principle of operation of the carburetor

The carburetor is an important component of an internal combustion engine, responsible for preparing the air-fuel mixture and supplying it to the working cylinder in the required ratio. A scooter engine with an unadjusted carburetor cannot function properly. The stability of speed, the power developed by the engine, gasoline consumption, response to turning the throttle, as well as ease of starting in the cold season depend on the correct settings of the engine power supply.

An important component of an internal combustion engine is the carburetor.

This unit is responsible for preparing the air-gasoline mixture, the concentration of the components of which affects the nature of the operation of the power plant. The standard ratio is 1:15. Leaning the mixture to a ratio of 1:13 ensures stable engine operation at idle. Sometimes it also becomes necessary to enrich the mixture by maintaining a ratio of 1:17.

Thanks to a properly configured carburetor, easy and quick starting of the vehicle engine is ensured, as well as stable operation of the engine, regardless of the ambient temperature. Any carburetor is equipped with jets with calibrated holes, a float chamber, a needle that regulates the cross-section of the fuel channel, as well as special adjusting screws.

The adjustment process involves specially rotating the screw in a clockwise direction or in the opposite direction, which causes, respectively, the enrichment or depletion of the working mixture. Adjustment measures are carried out on a warmed-up engine. In this case, the carburetor unit must first be thoroughly washed and cleared of blockages.

Features of setting up the carburetor of a 2-stroke scooter

The carburetor on the 2t scooter is slightly different in design and does not fit the 4t motor. The question of how to set up such a device worries all owners of two-stroke machines.

Most Chinese models have a fairly simple carburetor without unnecessary adjustments. The enrichment here is mechanical, although if you are tuning a scooter or you have a Japanese model, the enrichment can also be electric. In order to use the mechanical option, you must first pull the trigger on it, and then try to start the equipment.

Adjusting the carburetor of a 2T scooter is not difficult, but it does require some patience. In order to do this, you will need to disassemble the carburetor: first you will need to unscrew the top cover. The needle in it is fixed with a staple; it needs to be pulled out. The quality of the mixture is adjusted in the same way as described above. A feature of the push-pull system is that the needle affects the quality of the mixture only in a certain position. If the throttle valve is raised to its maximum, only the main fuel jet will be responsible for the fuel mixture. Sometimes the idle speed system interferes with it. Depending on what carburetor you have installed.

For a cold start, you need to use a starting enrichment, which must be closed after the engine warms up; Simply put, it's a suction. In such carburetors, the fuel level plays an important role. It is also regulated by mechanical intervention in the operation of the float chamber. It is configured in the same way as in the four-stroke version. In fact, the carburetor for 2t engines differs from models for engines on a 4-stroke scooter only in jets and some other parameters, but it is designed similarly, and therefore is regulated in the same way.

Why do you need to regulate?

During the adjustment process, the scooter carburetor needle is adjusted, the position of which affects the proportions of the air-fuel mixture, as well as a number of other adjustments.

Each tuning operation has a different effect on engine operation and fuel preparation:

adjusting the idle speed ensures stable operation of a running engine when the transmission is turned off;
changing the quality of the air-gasoline mixture using a special screw allows you to deplete or enrich it;
adjusting the position of the carburetor needle affects the change in the quality of the fuel mixture;
Ensuring a stable level of gasoline inside the float chamber avoids flooding of spark plugs.

A power unit with an adjusted carburetor operates stably in any conditions, is economical, throttle response, develops rated power and maintains speed, and does not cause problems for its owner.