2002-2007 Suzuki 500 LTA Service Manual, Page 76Get this manual
VALVE SPRING The force of the coil spring keeps the valve seat tightWeakened spring result in reduced engine power output, and often account for the chattering noise coming from the valve mechanismCheck the valve springs for proper strength by measuring their free length and also by the force required to compress themIf the spring length is less than the service limit, or if the force required to compress the spring does not fall within the range specified, replace it09900-20101: Vernier calipers Valve spring free length (INEX) Service Limit: 38.8 mm (1.53 in) Valve spring tension (INEX) Standard: 18.6 21.4 kgf31.5 mm (41.0 47.2 lbs1.24 in)