I was using 1 extra shim that came w/ motor (copper) w/ the ninja plug, ninja med header & ninja pipe...The 2nd motor before I started it I opened it to put in the shim and put oil in it & it sat on my work bench for a day. When I picked it up to put it in the car there was a nice little puddle of the after run oil that came out of the front bearing...Never had that happen before... The 1st motor did not do that and it ran perfect until the piston broke...The 2nd was hard to tune actually never got it 100% maybe air leak at that bearing, but still the hottest the motor got was 330 and I was out of fuel...