Question for y’all, my boys YZ250F has a noise in the motor. First when I bought it it ran fine however over time (Last year) the compression dropped off and at the end of last year developed a noise. So first thing I did was look at and replaces the valve shims to the proper size. Compression is back but the noise is also. Now there’s a hole on the bottom of the case (right side) and we have oil and or antifreeze coming out of it slowly. Even when just sitting in the garage. So I don’t know whether the leak is associated with the noise or not. What’s the hole for? Any ideas on the knocking noise? Seems to run good, idle good and has good throttle response. TIA! Ryan