Yamaha Warrior 350 87-04 Engine Motor Rebuilt PowerSportsNation Rebuilt Engines. Our process: Engines are completely disassembled. Cases are hot tanked or pressure washed. -All rebuilt engines include new piston(s) and rings, new gaskets and seals, new timing chain (where applicable), water pump seal kit (if water pump is part of assembly), new oil filter, and new spark plug(s). -Heads are refreshed or rebuilt (on a Rottler Head Machine SG7MTS) with the valves adjusted. All heads are checked for trueness and surfaced or planed if necessary. All valves, guides and seats are checked and replaced if needed. -Cylinders are always overbored to the next size or sent off and replated. -Crankshafts are inspected. If they are not in excellent or near new condition, they are rebuilt or replaced. If automotive style crank and rods are used in the application, all bearings are replaced. Crankshaft roller bearings are replaced where needed. -Transmissions (where applicable). All parts are visibly inspected or measured for wear. All bearings, shift forks and gears are replaced where needed. Any other worn internals will be replaced where needed. -Oil pumps are a crucial component in the build. They are all torn down and inspected. If they dont appear to be near new, they will be rebuilt or replaced. -Assembly begins after all parts are inspected and the replacement parts are on hand. Each engine is hand built with quality workmanship to insure the longevity of your powerplant. All bolts are torqued to appropriate specs for each engine type. -The final step in the process here at PSN is to test run your engine. Because of the vast inventory of used parts from our salvage operation we have been able to build test cradles or test rollers. We run 9 out of 10 engines that leave our facility. And are continuing to build towards 100% testing. This helps us catch any issues before they make it to the customer.