Gyaran injinan motoci ya ƙunshi maye gurbin bawuloli, pistons, linings na silinda, ko silinda, shafts na niƙa, da sauransu. Dangane da ƙa'idar shagunan 4S gabaɗaya, ana buƙatar a maye gurbinsu da na'urori guda 4 masu tallafi, wato, pistons, zoben piston, bawuloli, hatimin mai na bawul, jagororin bawul, shingles na crankshaft, shingles na sanda masu haɗawa, bel ɗin lokaci, ƙafafun tensioning.
Idan an tsara sarkar a kan lokaci, ya zama dole a canza sarkar lokaci, mai tayar da hankali, ban da injina, hannun silinda, shaft ɗin niƙa, bututun matsi mai sanyi, amma kuma ana buƙatar maye gurbin fakitin gyaran, hatimin mai mai lanƙwasa na gaba, hatimin mai mai lanƙwasa na baya, hatimin mai na camshaft, famfon mai, ƙarin bawul ɗin bincike, da sauransu, wani lokacin kuma ana buƙatar maye gurbin kayan haɗi na waje kamar faifan clutch, da sauransu. A takaice, yana da mahimmanci a maye gurbin sassan da ba su da tabbacin gyara injin don tabbatar da aikin injin.
