Cobra CX50 SR, Manual, Page: 64 / 80

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White spark plug
CAUTION:
It is much safer to operate the engine slightly rich as opposed to slightly lean.
This is because an overly rich engine will just run poorly while an overly lean
engine will seize, potentially causing an expensive top end rebuild and a DNF.
To richen the carburetor:
1. Change the main jet one number at a time (larger).
2. Lower the needle clip (raising the jet needle) one notch at a time until the
engine starts to blubber on the top end, then move the clip back up one notch
or until you get the blubber out.
FUEL MIXTURE SCREW
The smaller brass screw that is towards the front of the engine is a fuel mixture
screw. This screw will also richen and lean your engine more on the bottom and
mid-range. In warmer conditions, turn the screw in. In colder conditions, turn the
screw out. Be sure to keep the carburetor very clean and make sure you don't
have water or dirt in the carburetor bowl. Use automotive carburetor cleaner or
WD-40 to clean the carburetor inside and out.
Cleaning the carburetor:
Clean the carburetor in a well-ventilated area, and take care that there is no
spark or flame anywhere near the working area; this includes any appliance with
a pilot light. Because of the danger of highly flammable liquids, do not use
gasoline or low flash-point solvent to clean the carburetor.
1. Make sure the fuel is shut off.
2. Remove the carburetor.
3. Drain the fuel from the carburetor.
4. Disassemble the carburetor.
5. Immerse all the metal parts in a carburetor
cleaning solution.
6. After the parts are cleaned, dry them with
compressed air.
7. Blow out the fuel passages with
compressed air.
8. Assemble the carburetor
9. Install the carburetor onto the motorcycle.
CAUTION:
The motorcycle will only operate properly if the carburetor top is installed properly
with the mounting screws, cable and choke knob oriented as shown.