Save money Easy DIY replacement Retrofits MB165 Includes tensioner All in one package, the jackshaft assembly and steel clutch cover for the Baja Mini Bike MB200 (Baja Heat, Mini Baja, Baja Warrior) Now you can upgrade your older bike with this second generation jackshaft assembly All in one package, the jackshaft assembly and steel clutch cover for the Baja Mini Bike MB200 (Baja Heat, Mini Baja, Baja Warrior). Now you can upgrade your older bike with this second generation jackshaft assembly. This assembly has the 2-5/8″ chain tensioner arm. The jackshaft comes with one pre-installed 6203ZZ bearing. Because of the high degree of “wear and tear” on jackshaft bearings, we recommend our 6203ZZ bearings which we sell as a set of two. If and when you need a replacement bearing, it is always good to keep an additional spare on hand.,4 What all comes with the jackshaft assembly set This jackshaft assembly comes as pictured with the 2-5/8″ chain