By 'oil leak', are you referring to an actual oil leak where you have a pool of oil either on the floor or within the sled or do you mean a leak in the sense that it is being burnt and you can smell the residue? Reason being is that you mention the area under the handle bars which is exactly where the exhaust flex joints and clamps are located and is also where those exhaust gaskets can deteoriate overtime and cause an exhaust leak which could smell like oil being burned. Additionally, the engines in the 03-04 RX-1's were known to consume some oil; some more than others. If you think you have an exhaust leak, start the sled and then use old rags or thick gloves and block the rear exhaust outlets. If it stahls, then you do not have an exhaust leak. If it stutters but stays running, then you have yourself a leak to contend with which would either be those 4 exhaust gaskets or the two exhaust gaskets on the crossover pipe going into the muffler.