1998-2000 Yamaha WaveRunner GP800 Factory Service Manual, Page 93Get this manual
al_C_VL_IN_D_E_R_S_ C_E:_:: SERVICE POINTS
Cylinder inspection 1Eliminate: Carbon deposits (with rounded scraper Q)
2Inspect: Cylinder water jacket Corrosionmineral deposits Clean Cylinder inner surface Score marks Repair with 600800 grit wet sandpaper or replace
3Measure: Cylinder bore "D" (with cylinder gauge) Out of specification ReplaceNOTE: Measure the cylinder bore in parallel and at right angle to the crankshaftThen, average the measurements