I recently purchased a 2004 yz450f it ran but had to b pull started then ran like shit so i thought timing and valve adjuStment. Well i looked at the timing and it was not even close to being right and the valves were way out of spec. So i re did all of that and as i was putting the head back on i notice a drip of oil Come out of the top right of the head looks like a hole about the size of a penny its got a hole for a screw and theres no screw in it so i looked at a oem diagram and the service manual it dosent show a bolt that goes there? Can anyone tell me what this hole is for? And Should i put a bolt in the bolt hole on thw side of it where it looks like 1 is missing?