The Harley EVO engine is pretty much bullet proof with one exception, the breather gear is the weak link. The factory gear is made from plastic and absorbs dirt & material, the OEM gear can also warp (melt) and can ruin the bore in the cam chest. Fragments of the plastic gear can get caught in the suction side of your oil pump, which can cause wear and or seizure of the oil pump. If this happens your flywheels can be bathed in too much oil in the crank case, which can slow your engine and create heat from friction. If your oil pump isn’t pumping oil engine seizure is usually what’s going to happen. We install an S&s Cycle Breather Gear when installing cam shafts, lifters & pushrods... So, if you are opening your bikes cam chest, change the breather gear. We have them in stock.