Is backfiring lean or rich?

Lean Air/Fuel Mixture Not only can a rich air/fuel ratio cause a backfire, a mixture that doesn’t have enough gasoline can cause a backfire, too. When a lean mixture combusts, it burns more slowly, meaning there will still be some air and fuel that isn’t used up when the exhaust valves open — leading to a backfire.

What does the pilot screw do on a carburetor?

The pilot air screw and pilot jet. The air screw can be located either near the back side of the carburetor or near the front of the carburetor. If the screw is located near the back, it regulates how much air enters the circuit. If the screw is turned in, it reduces the amount of air and richens the mixture.

Does backfire mean rich or lean?

Not only can a rich air/fuel ratio cause a backfire, a mixture that doesn’t have enough gasoline can cause a backfire, too. A “lean” mixture is one that doesn’t have enough fuel, and too much air.

What does the air screw do on a Mikuni carburetor?

The air screw can be located either near the back side of the carburetor or near the front of the carburetor. If the screw is located near the back, it regulates how much air enters the circuit. If the screw is turned in, it reduces the amount of air and richens the mixture.

Where can I get Mikuni tuning and jetting parts?

They also have parts for PWCs, ATVs and snowmobiles. They’re one of the largest Mikuni dealers anywhere and their prices are very reasonable. They also have a great selection of parts, fast shipping and superb customer service.

Are there any carburetors that match the Mikuni?

No carburetor made today can match the Mikuni in this regard. We have chosen tuning components that, for the great majority of applications, are correct. Chances are, you have had to do very little beyond adjusting the air screw and idle speed screw.

What are the characteristics of a Mikuni jet?

1. Main Jet Size 2. Poor Mid-Range Performance 3. Backfires Through Carburetor 4. Backfires in Exhaust 5. Detonation (“Spark Knock”)

What should venturi size be on Mikuni bike?

If you put on too big or too small a carb, your bike is going to run like kaka – if at all. Let’s say your bike is basically stock. You pull off the old carb and determine that the venturi size is 28mm on that carburetor (this can be done by measuring with a caliper).