'06 YZ450F. So I was halfway across the country at a huge supermoto event when I was doing a double, landed, heard the motor start knocking. got advice from a few others before I axed my weekend, the consensus was the sound was a rod knock. Thank god I had my 150 with me to stay the weekend and play.
So I just put the motor on the bench and tore the top end down figuring I would find play in the rod or crank bearings, feel it by hand.
But nothing, everything feels tight! tight tight tight.
The full picture: burns about 6oz of oil each race. cam chain is also tight. checked the valve clearances before I removed the cams. They were all over the place. Intake specs .10-.15 mine were (3 valves left to right) .152 .102 .076 Exhaust specs .20 - .25 Mine were .432! and .178. It has the HC graves piston which only has one compression ring, stock bore. Also graves exhaust that always has play in the header but no way could that have been the sound.
The sound was a knock, when up and down with the revs, sounded like a single rotational knock, like a rod or crank, not like a top end problem.
I really don't want to split the cases and spend money if I don't need to, so let the ideas flow, please. Thanks