Ball bearing lubrication requirements

[Prodigium]

I have a small, 150cc, 4 stroke, water cooled Honda scooter. It uses ball bearings everywhere except the big end bearing which is a roller bearing and it gets pumped flow to it, the rest are splash. There is no filter, which is what I'm going to remedy. My question is this; Am I correct in thinking ball bearings need clean, cool oil at good flow rates and that pressure isn't as important as it is in plain metal bearings? Looking at the engine's oil system design that would appear to be the case since all but the big end are splash lubed. Where can I find lubrication requirements for ball bearings? I use synthetic oils, Royal Purple or Red Line.

 

[romke]

usually ball bearing suppliers do supply ample information about the lubrication requirements of their bearings, based on the bearing speed and the dimension of the bearing.

ball bearings require very little oil and the pressure of the oil supplied is not important - the oil pressure is build up in the bearing itself based on the temporarily generated elasto hydrodynamic conditions between roller/ball and raceways.

that is reflected in the design you mention, only with the "hidden" bigend bearing there is a need to generate an ample lube supply, problably more for carrying away excessive heat then for lubrication itself.

a filter will ofcourse clean the oil, but you should bear in mind that we have here a lowcost design where in fact worn bearings can be replaced at very little cost - most likely a lot less then the cost of the cost of an additional filter, a pressure relief valve and the necessary piping. so, unless you want to achieve a much longer useful engine life then the designer had in mind, i would not go into all the trouble.