Harley Davidson: from EFI injection to step by step carburetor

In this article, we will realize the dream of the most loyal followers of the old school: we will eliminate twin cam Harley Davidson's syringe and replace it with a vaporizer to return everything to the "before" state.
First of all, I want to make it clear that this change is purely experimental and aesthetic, for nostalgic guidance, because in this case there is no really necessary change: the injection is normal, the engine is running properly. Although it can set an example for those who want to make a replacement to eliminate system failures, such as Marelli's magnetic injection and malfunctions at a considerable distance.

Special carburetor
First, we will review the list of three elements we need to completely eliminate our EFI injection system:
-vaporization Your admission record
-Gasoline faucet Use your adapter
-Compatible with ignition module.
Let's start with the carburetor: in our case, the engine is a 100ci screw'eagle model with a lot of compression, quite "bad milk," and we're going to use an S & s super "g" carburetor, refitted by American experts, triple X and chrome, until the last corner.

Major modifications include the installation of a new mechanized device inside the Ventura, the installation of a circulating or "booster" transmitter, and the addition of two detonator circuits. These circuits are very demanding to operate, and their effect is similar to an additional acceleration pump, which will push us to infinity.

We selected the gasoline faucet and its adapter from the pingel catalog, which is a product with high performance and reliability.

Ignition must be current compatible. Crank rotation sensor Originally, this sensor will be the only sensor that will be reused from the injection system.

This magnetic sensor will show us the position of the piston very accurately so that the spark can release the spark at the right time. We used it Altmann motorcycle ignition P3 systemVery reliable, easy to install and compatible with the original coil and HD safety system.

Dismount!
Now that we've got all the components, we're moving on to the most interesting part: we're going to remove sensors, input cables, switches, and anything else in the EFI system (except for the stork position sensor mentioned above).
After removing the fuse from the injection pump (the workshop manual must be consulted throughout the process), we will attempt to start the engine to relieve the pressure on the injection pump.

Then we will turn off the negative pressure injection battery and remove the fuel tank, and then we can remove the EFI conductive module.

Then open the hatch at the top of the warehouse,

In this way, we can take out the syringe and release the high pressure pipe, which will allow us to quickly extract the fuel pipe.

Let's pause
Congratulations, we have finished nearly half of the work! Before installing the new components, we will focus on removing all sensors and cables that are no longer used in the system. To do this, we can look at the cable diagram at the end of the workshop manual so that we can restore a very simplified and practical power system, In addition to improving the aesthetic effect
Now it's time to take a break and review what we've done to prepare for the next step, assemble.

Installation of vaporizer

We will continue to complete the "countdown" or convert the EFI electronic injection system into a vaporization system. In the first part, we listed the new elements and removed the parts to be destroyed. We only had to remove the O2 sensors in the exhaust and replace them with a plug. We are now assembling.

A. Fuel depot
In order to resume the project, we will start with the simplest part. After re closing the upper gate of the gasoline depot, we will install the fuel faucet and adapter of the faucet, and use a small amount of liquid sealing or softener to prevent fuel leakage.

 

A. Acceptance
We start with the connector or multiple joints, as always, according to the workshop manual and the component manufacturer's instructions, install the "loose", place the carburetor in its final position, supported by its bracket, and press the screw at the inlet tightly to mark its position to ensure that it does not He moved Now, we can dismantle the carburetor and reinterpret it according to the specified value, while always trying to ensure that the position taken is not moved so that it is exactly in line with the carburetor and there is no air leakage at the inlet.

Then we installed the carburetor, the bracket and the air filter, and in this case, we chose a performance factor machine to enhance the offensive aesthetics while increasing the welfare.

In the next photo, we can see the location of the two detonator scatterers and their photos in carburetor Cuba.

Ignition device
If we follow the instructions, the ignition device is very simple, we only need to connect the positive, negative, coil and position sensors.

We will select the location of the module in a safe location for elements and rain (e.g. under the seat).
It's important not to run and try to connect and locate as much as possible, he cautions that 90% of engine failures are due to faulty connections.

After that, we can choose the three square positions of the ignition module, where we will choose the progression curve (green) and its type (yellow) and RPM limit (red).

Final test
Once we have the carburetor, the ignition system and the electric system, we will re install the fuel tank on the motorcycle, connect our new faucet to the carburetor, and have the proper fuel pipe.
We reconnect the negative borne of the battery, we can start the engine, check that everything is OK, and make adjustments.
Tech Tip: In the case of the S&S carburetor and CV (original HD) is very simple adjustment, the motor is heated slightly and the idling screw is tightened until about 1000 RPM is obtained. Then we slowly close the mixing screw until the engine starts to fail, and memorize this position. Reopen the mixing screw until the engine starts to fail again and we memorize the position. The ideal setting is approximately between the 2 positions, we do it and we return the idling to about 850 RPM. Voila!
Now we can put on the helmet and go out on the road brand new the new way of breathing from our beloved Twin Cam (Figure 10), we will see that although the power is similar, the way to deliver it is more "raw" and the bike no longer asks permission to accelerate, it simply does!

Frank Burguera

#mecanicaharley