Went on my First ride on my 2 used quads this weekend. ’09 550, 800 miles on it and ’07 700 1700 miles. Idling pretty quiet, rev them up in park (not bouncing them off the limiter, just goose the throttle) you can hear a distinct singular (klock) noise, kinda like a a loud spark knock. (using 93 octane gas). Put them in gear and start to accelerate and what I can best describe as a low end rod knock type noise. Is this normal?!! I cant tell if its in the clutch area or the motor… I,m kinda lost here. I’m a mechanic by trade and i thought maybe one bike but both of them do it, but idle them and they are quiet, no knocking noise??? and im thinking it was getting worse by the end of our outing. (may just be me being a worry wart). I plan on going to a trail meet this weekend and don’t want to have a catastrophic failure 10 miles out into the woods. I can deal with having to put motors in them, i just don’t want to blow holes in the short blocks and make them unrepairable. Please let me know if this is normal, i haven’t been around or rode any other bike to know if it is or not. No Performance issues, they both s#$t and git just fine otherwise.