Apply an incredibly thin layer of the flexible adhesive over the pinhole using a toothpick.
: When the throttle is wide open, the main jet size acts as the restrictive bottleneck controlling total fuel delivery. Step-by-Step Rebuilding and Maintenance Roadmap BS Carburetors - Mikuni Power
Retains fuel; often contains a 90-degree drain hose.
Once reassembled and installed with a sealed or patched diaphragm, use this matrix to diagnose and fine-tune your performance: Probable Cause Corrective Action Lean condition or vacuum leak at the intake boot.
A “patched” Mikuni BS25 diagram is a testament to practical mechanic ingenuity—correcting lean factory tuning and wear. However, it is not a substitute for genuine parts. The most successful patches combine annotated diagrams with and diaphragm leak testing .
Connect a clear or black vinyl hose to this nipple and route it beneath the engine chassis. This safely drains fuel away from the engine bay when flushing the bowl or if the needle valve sticks open.
Ensure all rubber seals (gasket, diaphragm, O-rings) are seated correctly. 4. Tuning the BS25 After Assembly Once rebuilt, the BS25 requires tuning.
