I bought a 800 outlander with a knock in engine , I do not know any history on it . I tore the motor down and can not find anything out of spec. the clearances are all in tollarance. The only thinge I found is the front piston was installed back wards , that is the piston in the front had the arrow pointed towards the intake , the book clearly states that it should be pointed towards the exhoust , could this be the knock ???? if so how much damage would it have done . It has just over 2000 mi 275 hrs. could this have been done at the factory ??? . I kind of dought it , but why would someone have taken it apart with so few miles??? It has a standard bore. Could anyone shed some light on this ??? I hate to put it back together and and find out it still has a noise. ANY IDEAS ??? thanks