What kind of carburetor does a Keihin use?
The information presented here is applicable to any brand of motorcycle that uses the ubiquitous Keihin FCR carburetor.
What causes lean bog on Keihin FCR carburetors?
(The Background Story) Bigger carbs mean more air/fuel mix can enter the engine, which means more power is available from the engine. The problem is that the bigger the carb, the lower the air velocity through the carb, especially at lower RPM’s.
Where is timing screw on Keihin FCR carb?
In addition to squirt duration timing, there is also a need to control when the squirt begins. Too soon, and it will hit the back of the throttle slider valve. Too late, and the engine will be starved for fuel. The first photo is of the timing screw location on this 2007 CRF250R FCR carb.
When to start fuel squirt on Keihin FCR?
This ensures that when the throttle is stabbed, the squirt will start at the exact moment the throttle clears the stream of fuel. The timing needs to be adjusted so that the squirt starts just after the throttle plate gets out of the way. This will need to be done every time the leak jet is changed.
The information presented here is applicable to any brand of motorcycle that uses the ubiquitous Keihin FCR carburetor.
(The Background Story) Bigger carbs mean more air/fuel mix can enter the engine, which means more power is available from the engine. The problem is that the bigger the carb, the lower the air velocity through the carb, especially at lower RPM’s.
In addition to squirt duration timing, there is also a need to control when the squirt begins. Too soon, and it will hit the back of the throttle slider valve. Too late, and the engine will be starved for fuel. The first photo is of the timing screw location on this 2007 CRF250R FCR carb.
This ensures that when the throttle is stabbed, the squirt will start at the exact moment the throttle clears the stream of fuel. The timing needs to be adjusted so that the squirt starts just after the throttle plate gets out of the way. This will need to be done every time the leak jet is changed.