The clutch spring service limit on your 650cc twisted twin is 38mm. As you can see, the spring in the above photo is just below the limit. Replace the set if any of them measure below 38mm. Need more? I like the EBC kit found on eBay US, eBay AU, eBay UK, eBay CA and Amazon.
One of the easiest ways to measure them is using vernier calipers – we’re using a set of Kincrome digital vernier calipers in this case. Plenty of other options for vernier calipres on eBay US, eBay AU, eBay UK, eBay CA or Amazon. More accurate than a ruler!