If original, which yours probably is, you will find the MC size stamped somewhere on the body, in your case most likely a "14". An aftermarket rebuild kit would set you back $20 to $30 (don't even ask about an O.E.M. one, lol), so as mentioned, a different smaller sized MC would make sense. It will give you better "feel" and modulation but there is a small trade-off - it will also give you more lever freeplay. I recently put an 11mm MC on my '78 and while it has improved the "feel', I'm not crazy about all that added lever freeplay. I have a 1/2" (12.7mm) MC to try on my other 650. This is about half way between the 11 and stock 14. I'm hoping this may be the ideal compromise, better "feel" than the stock 14 but not as much lever travel as the 11.
If you research handlebar options, you will no doubt find my recommendation for the Euro bars. They are the best handlebar bend out there in my opinion, lower than either stock type but not too low. Also, the way the ends droop down slightly turns your wrists to a very natural and comfortable angle, providing you've mounted them correctly (rise in line with the fork tube angle). The drooped ends also allow an angled Special MC to mount up (almost level) and work OK.
And for the Euro bars, a commonly available 90cm long 1 piece line works perfectly .....
They can be had for as little as $5 off eBay .....
https://www.ebay.com/itm/45-120mm-M..._trksid=p2060353.m2749.l2649&autorefresh=true
If you research handlebar options, you will no doubt find my recommendation for the Euro bars. They are the best handlebar bend out there in my opinion, lower than either stock type but not too low. Also, the way the ends droop down slightly turns your wrists to a very natural and comfortable angle, providing you've mounted them correctly (rise in line with the fork tube angle). The drooped ends also allow an angled Special MC to mount up (almost level) and work OK.
And for the Euro bars, a commonly available 90cm long 1 piece line works perfectly .....
They can be had for as little as $5 off eBay .....
https://www.ebay.com/itm/45-120mm-M..._trksid=p2060353.m2749.l2649&autorefresh=true