[QUOTE=old polaris tech;3302094]Don't have a sealed bearing for the water pump on the 400! Have had people try that years ago and they didn't last. It has to be open to receive the oil that's in the counter balancer cavity to keep it constantly lubricated. It along with the counter balancer bearing and oil pump driven gear bearing(at the end of the counter balancer shaft) are lubricated by this small amount of oil, 100ccs or so that's in the cavity.This is a high speed small bearing. You can remove the shielding on the inner side of this bearing if you wish and that would probably work ok and it would get enough oil. Several different kits are available on ebay from a small set to a complete engine bearing and gasket kit.New Polaris ATV 350 400 90 03 Sportsman Crankshaft Main Bearing Oil Seal Kit Set | eBay New Polaris ATV 400 90 03 Sport Complete Engine Bearings Gasket Rebuild Kit Set | eBay[/QUOmy motor was rebuilt to a 440 scrambler from the top to bottom and it is running good they have done a great job on it because it never gives me trouble just start right up now with out a problem good job on it