Sports Carb for Motorized Bikes
Increases performance with a sports carb
Sports carburetor
Check tour tuning infographic to understand how the carb should be used with other high performance parts
Featurs of the sports carburetor
The Sports carburettor for motorized bikes is a significant advance on NT and ‘Speed’ carburettor’s.
This new design has better all-round performance with noticeable improvements:
- easier starting,
- smoother idle,
- clean and crisp acceleration, and
- good high speed performance.
The carburetor has a large, effective air-cleaner that is easily removed for servicing, and a choke system that is safer and easier to use. The competition style flat plate throttle slide helps to create a compact design and, combined with the full height spray-bar, gives a crisp and rapid response to throttle operation.
The sports carburetor also has a built-in, serviceable fuel filter and a cuff-seal to ensure an air-tight fit on the inlet manifold. The end result is a quality built product that will give years of reliable service.
This carburetor also has a built-in, serviceable, fuel filter. The fuel Inlet inlet pipe can be rotated to any position. this ensures that the fuel line has no sharp bends while optimizing fuel flow.
A rubber cuff-seal is fitted to seal against the inlet manifold. The cuff seal provides an air-tight fit on the inlet manifold and help reduce vibration that can effect fuel flow.
The end result is a quality built product that will give years of reliable service.
Diagrams of carb components
Sports carburetor
Filter housing dismantled for cleaning
Sports carburetor
Location of Important components
Features of the sport carburetor
This carburetor also has a built-in, serviceable, fuel filter. The fuel Inlet inlet pipe can be rotated to any position. this ensures that the fuel line has no sharp bends while optimizing fuel flow.
A rubber cuff-seal is fitted to seal against the inlet manifold. The cuff seal provides an air-tight fit on the inlet manifold and help reduce vibration that can effect fuel flow.
The end result is a quality built product that will give years of reliable service.
Installing the Carburetor
Fitting the throttle cable
Before proceeding:
It is easier to fit the throttle cable to the carb body of the carburetor before installing the carb to the motor. It is also easier to set up the carb if the throttle control and ignition switch assembly have been fitted to the handle bar.
It is important to make sure you will be able to install and remove the carburetor once the motor is installed on the bike, (see our engine fitting instructions – ‘Will the Motor fit?’
Cap of sports carburetor
Remove carburetor slider
Remove the slide from the carburetor
Remove the Slide and Cap Assembly from the carb:
1. Remove the two screws retaining the cap and gently remove the assembly (see image left).
2. Remove the spring and slide (see image left). Note the thumb is controlling the choke locking lever.
CAUTION: The choke locking lever may get caught in the body of the carburetor. Gently twist and wriggle the lever loose without damaging the gasket. Note that it is not essential to install the cable elbow.
3. If the cable elbow is to be installed in the cap, fit it so there is about one thread visible above the cap.
4. Thread the cable through the elbow and fit the slide and spring
Assemble as shown in the image next page.
CAUTION: Take care not to damage the gasket. A torn gasket can cause air leaks that may upset carb tune.
5. Re-install the assembly as shown in image right.
6. Fit the Screws and compress the Spring until the cap sits squarely on the carb body, If the alignment is correct, the screws will freely screw into the body. If they are tight, then they are misaligned. rock the cap a little to correct alignment
WARNING: Do not force the screws. You will do permanent damage to the carb body.
Be careful to get the choke locking lever in place. The spring tension on the lever can cause the cap to not seal correctly on the carburetor body.
Check the throttle opens and closes correctly
Carburetor slider
This image shows the throttle cable fitted on the carburetor slider.
7. With the cable assembly fully installed check the throttle opens and closes smoothly and returns to the idle stop when the twist grip is released. If not check the whole assembly from the handle bar to the carb for the fault, and correct it. Once the throttle slide is working correctly, move to the next step.
8. You now need to check the automatic choke function is working correctly. Depress the choke lever (on the RH side when the carb and motor is installed on the bike). The lever should latch in the ‘closed’ (down) position.
9. Turn the throttle control so the slide is fully open. The choke should now be in the ‘open’ (up) position. Repeat steps 8 & 9 a few times to check the system works consistently.
Choke release
10. If the choke does not release easily, it is usually due to the cable adjustment being set too long. Adjust this by turning the barrel nut at the throttle control end so more thread is showing and/or the feral on the cable elbow in a similar manner. You should find a setting where the slide drops to the idle position and the choke releases easily when full throttle is applied.
11. Install the carburetor on the motor and tighten the clamp screw just tight enough to stop the carb from turning when you try to move it.
12. Connect the fuel line and you are ready to go! You can change the angle of the fuel line on the carb by easing the screw on the filter housing cap and rotating the cap to the desired angle and re-tightening the screw.
CAUTION: You only need enough torque on this screw to prevent fuel leaks and the cap from rotating, be gentle!
Offset inlet manifold
Offset inlet manifolds are a great way to find space for the carburetor if it is touching the bicycle frame
Space for the carburetor
If the carburetor air filter is touching the saddle stay, it is often necessary to fit a small 10mm spacer block on the rear engine mount. This will provide extra clearance between the seat stay and the air filter fitted to the carburetor.
When installing the motor you can set this clearance so the carburetor can be fitted and removed without the need to touch anything else.
If there is still insufficient room in the frame to mount the carburetor you can purchase an offset inlet manifold. The replacement manifold sets the carburetor to the side of the engine so that it will clear the frame.
To get up and running on your bike, read the user’s notes for starting and running in procedures
If you need further Help Contact us though our blog page. Our customers and mechanics will try to help with your issues.
