I recently changed engine oil of my Apache rtr 160. I used otul 5100 15W50. Later I started experiencing vibrations, a lot of vibrations. I checked on the engine oil. The quantity is reduced to half. No engine oil leak found. Quantity that I poured in was 1ltr. Required quantity is 1ltr. What could be going on?
You should clean the area around the bottom drain plug, fill the oil back up to capacity, run the bike and check to see if the leak is at the drain plug. The aluminum washer which seals the plug can become "squished" at some point and require replacement. On my car, I replace this washer every time I change the oil, though it does come in the oil filter kit (along with needed o-rings and filter). This is the most logical place for the leak to be occurring. The oil can either be burned or leaked. Since (I assume) you are not seeing voluminous amounts of blue smoke coming out of the tail pipe, you have to assume it is being leaked.