When to change the pilot on a carburetor?
You need to determine this by pilot screw position. If not running (idling around 1k RPM) optimally between 1/2 and 2 1/2 turns out, change the pilot. Another way is by backfiring on a YZF on decel, too lean. Richen up by turning pilot (fuel) screw out. If you go more than 2 1/2 turns to get rid of backfiring, change the pilot richer (bigger).
Which is the best carburetor for a race car?
Lets say the main jet that runs best is a 180. Your new STP main jet is a 180/.963 = 187. If you go to sea level to race on a 70 degree day this is what you should try first. If you go up to ride at Rampart Range, 8000 ft on a 80 degree day, your CF=.918. So you should try a 187 * .918= 172.
How big should a carburetor be for a scooter?
Carburetor diameter(12mm) x 5 = 60(or number it calculates) x 0.9 = sea level jet size. For Denver: Take 0.948(Denver atmospheric pressure at 70 degrees) x jet size(60) = new jet size(56.88) round up 57 would be the proper jet size to start at for a stock scooter using a 12mm carburetor.
How do you adjust the idle speed of a carburetor?
When it’s at running temperature, find the 2 screws on your carburetor that adjust the air and fuel mixture. You can then use a screwdriver to adjust both screws ΒΌ turn at a time until your engine purrs smoothly. To adjust your idle speed, find the idle mixture screw that limits the flow of fuel at idle.
You need to determine this by pilot screw position. If not running (idling around 1k RPM) optimally between 1/2 and 2 1/2 turns out, change the pilot. Another way is by backfiring on a YZF on decel, too lean. Richen up by turning pilot (fuel) screw out. If you go more than 2 1/2 turns to get rid of backfiring, change the pilot richer (bigger).
Lets say the main jet that runs best is a 180. Your new STP main jet is a 180/.963 = 187. If you go to sea level to race on a 70 degree day this is what you should try first. If you go up to ride at Rampart Range, 8000 ft on a 80 degree day, your CF=.918. So you should try a 187 * .918= 172.
Carburetor diameter(12mm) x 5 = 60(or number it calculates) x 0.9 = sea level jet size. For Denver: Take 0.948(Denver atmospheric pressure at 70 degrees) x jet size(60) = new jet size(56.88) round up 57 would be the proper jet size to start at for a stock scooter using a 12mm carburetor.
What should my carburetor be at sea level?
If you go to sea level to race on a 70 degree day this is what you should try first. If you go up to ride at Rampart Range, 8000 ft on a 80 degree day, your CF=.918. So you should try a 187 * .918= 172. (You need to use the STP jet size as the base).