Need some help on this, Im looking for a NOS spring for the secondary on my '78 EX 440, Yamaha lists two part numbers, a 90508-45286-00 and a 90508-45287-00. What's the difference between the two numbers? Thanks
I have an old spring chart for you...but can't post it. Looks like I have to resize it. Any easy way to post a pic ?
The 286 yellow spring is brutally soft. Best to work with a stiffer secondary spring for better back shift and control the rpm with ramp weight. Good luck.