Sods law.... Bike ready to start. Get it running briefly. Then, the kick-start breaks. The boss that attaches to the spline has sheared off. Apparently it's part number 498-15621-00
I have found one on Ebay in Germany that says it fits. However,  the part number is 278-15621-00. I've sent a message, but no reply in a week. Can anyone advise if the part will fit? It's £60, and a PITA if it's not correct, so any info greatly appreciated. Thanks 

I have a complete kickstarter nice tight swivel and good rubber   100 bucks  canadian  if it comes to that
Doug

I believe there's a whole thread on here about the boss and commonly available part that can be used to replace it. 

I don't have time to read through the whole 6 pages but here's a link to what my "best guess" was...  I think the 583 part did work.

yamaha-enduros.com/index.php/forums/74-7...eeded?start=10#99411

HI  MBUTCHERS, I had the same thing happen to me, I looked on e-bay and found one for an MX 400 which fits perfectly I also think that the splines on the kick start shaft are the same size as the 250s, so if you know anyone with a 250 ask them if you could just try theirs on your bike to see if it fits .

Mbutchers 278 superseded to 583 partzilla has it in stock 

I've got an XS650 on my 360. Splines seem to be the same for many years. Just depends if it clears things when folded out, or folds up tidily without hitting the case. Just googled for a pic & this popped up below.

www.mikesxs.net/motorcycles/Yamaha/XS650...trols/kickstart.html