[Product Details] The oil pump is not disassembled. Therefore, there is no specific maintenance method. When the product fails, it is an assembly replacement, but you should replace the two rubber seals of the plunger large and small. We will send the URL of service manuals that include the oil pump deployment diagram, inspection, and adjustment. Oil seal large and small 1 each, gasket large and small 1 each. Compatible models: YB-1 YB50 YB90 R1-Z TDR250 TZR250 1KT 2XT RZ250 350 DT20 DT20 R TZR1 25 SDR200 *Compatible with the pump shown in the picture. Main unit not included.