In this month's tech talk, Carl dives into the fundamentals of carburetor jetting.
First, it's crucial to ensure that your motorcycle is fully warmed up before making any jetting adjustments. The richness of the air-fuel mixture changes with temperature, so you should only evaluate jetting when the bike is at operating temperature.
The richness of the mixture is controlled by three mechanisms, so you should adjust also your jetting accordingly. Idle and low RPMs are controlled by the air-fuel mixture screw, mid-range is managed by the needle, and top-end is governed by the main jet. Avoid mixing jet components from different manufacturers, as they are typically not compatible. Using jets and needles from the same manufacturer ensures optimal performance.
When opening the carburetor, use a high-quality JIS screwdriver to avoid stripping screws. Then, follow a systematic approach: make one change at a time and evaluate its impact before proceeding. For vacuum-operated carbs, which can have sluggish performance at low RPMs, avoid cutting the return spring or drilling holes in the slide, as these changes can compromise safety.
We also recommend marking various throttle positions using masking tape. This will help you identify where adjustments are needed. Perform steady roll-ons in different gears to assess the bike's performance across the RPM range.
Proper float height adjustment is also crucial to prevent fuel starvation at high RPMs. Refer to your bike's service manual for the correct specifications.
Check out our video for more details!
As always, if you have questions, don't hesitate to e-mail, call, or text us!