If the bearing feels gritty, take the engine apart and try to wash the case out completely. Soap and running water to make sure any debris is flushed out. Blow it dry and rinse it in clean fuel and dry it again. See the bearings feel free afterwards. Rinse all the internals in clean fuel and blow them off and assemble the rest of the engine with a light oil coating. Everything should feel good, if not then something may be wrong.