2008-2010 Kawasaki KFX450R Factory Service Manual, Page 84Get this manual
FUEL SYSTEM (DFI) 3-27 DFI System Troubleshooting Guide
Symptoms or possible Causes Valve spring broken or weak Valve not seating properly (valve bent, worn or carbon accumulating on seating surface) Actions (chapter) Inspect and replace (see chapter 5)Inspect and repair or replace (see chapter 5)