I can't find what the rear spring rate is that came stock on my 83' XR500R. The dealer says there was only one rate offered so the books won't show it. Race-Tech claims it's a 9.8kg/mm spring but that's bigger than anything they sell for that bike. XRs Only thinks it's a 580lb/in and that's almost the same as a 9.8kg/mm ~ 550lb/in. Anybody have an idea? I just scored a new in package Progressive Baja 580/680 lb/in spring off E-Bay for $16.