Sorry to revive an old thread, but fiche shows both 8mm and 15mm stems for a '86 K75c, and I see a few posts where folks are recommending the 11.3mm Bikemaster stems. So confusing. Going to go with the Moto-D angled valve stem, but what size do I really need; 8.3 or 11.3 mm are offered.
Thanks to those with the experience!