The 250 / 490 J has these listings but my notes don’t give specs for the G / H models
5X5-22212-10-00 SPRING (K=3.25) (HARD) U. R. ALT. PART (WHITE/GREEN)
5X5-22212-00-00 SPRING (K=3.5) WHITE/YELLOW
5X6-22212-00-00 SPRING (K=3.75) HARD (WHITE/BLUE) ALTERNATE PART
5X6-23141-10-00 SPRING, FRONT FORK (K=0.275) SOFT
USE SPACER 5X6- ALTERNATE PART
5X6-23141-L0-00 SPRING, FRONT FORK (K=0.305) 2
5X6-23141-20-00 SPRING, FRONT FORK (K=0.325) HARD
USE SPACER 5X6- ALTERNATE PART
YZ 250 F is listed as...
90501-99480-00 SPRING,COMPRESSION (K=2.96 K=5.05 KG/MM)
HARD (PAINTED RED) ALTERNATE PART
90501-99479-00 SPRING,COMPRESSION (K1=2.55 K2=5.03 KG/MM)
HARD (PAINTED BLUE) ALTERNATE PARTS
90501-99481-00 SPRING,COMPRESSION STD (PAINTED YELLOW)
2X4-23141-10-00 SPRING,FRONT FORK (K=0.214KG/MM) SOFT
(USE SPACER W4-23118- LO WITH SET)
2X4-23141-L0-00 SPRING,FRONT FORK (K=0.268KG/MM)
2X4-23141-20-00 SPRING,FRONT FORK (K=0.333KG/MM) HARD
(USE SPCR. W4-23118- LO WITH SET)