Originally Posted by ZeeOSix
Originally Posted by Taurus77
Hello everyone, checking the connection tolerances between the crankshaft and connecting rod on the workshop manual of the Honda CB 1300 I realized that these are very similar to those of the MV Agusta F4 1000 R with the difference that the oil pump reaches a higher pressure , about 7 Bar while in the CB 1300 about 6 Bar at 5000 rpm and 80 ° C.
Surely the MV reaches 7 bar of pressure at a higher rpm. In your opinion, with these clarifications, are there valid reasons not to use a 10w60 oil?
Those rod and crankshaft journal bearing clearances are basically the same as the Hayabusa and XSR specs I posted earlier. I'm betting about every modern motorcycle basically has the same bearing clearances.
Both manuals for my bikes don't even mention a xW-60 oil spec. Thickest oil they recommend is a 10W-50 or 20W-50. The thinnest viscosity they recommend is 10W-40. IMO, there is no need to run a xW-60 motor oil.
How much oil pressure a certain engine makes has no bearing on what oil viscosity to use.
Fact is, if too thick of oil is used, it's possible the oil pump will operate in pressure relief/bypass more often and that will reduce the flow volume of oil to the engine.
THIS. I'm so glad you brought this up!
I like banking on the benefits of thick oil, but the engine as a system has it's limits. This is one of the biggest, and it becomes riskier as you talk about engines that have higher and higher peak RPM.