A two-stroke outboard carburetor may need to be cleaned or rebuilt if it's not idling properly, or if the motor hasn't been started in several months. A dirty carburetor can't regulate the air and fuel mixture properly, which can cause stalling. A two-stroke engine needs a clean carburetor to avoid running lean, which can damage the motor.
 
This service and tuning guide provides the recommended factory stock jetting for each model. You might need to re-jet a two-stroke outboard carburetor as you tune and modify the motor.
 
Our WMH WHV Jet Rebuild Manual in PDF for the Mercury 2.5 Liter is available here for immediate download.
 
This 47-page Service Manual covers all the WMH and WMV carb models found in 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, and 1999 model year Mercury Marine / Mariner 2-Stroke outboard.
 
This is for immediate download in PDF format.