Originally posted by Top Gun 777
Hey D.
inital setting on clearnce for cranck sitting in case is 0.02mm on side-it is done to keep vacuum to escape from front side. Ones your first bearing fail and shaft ws grabing crancse this clearnace grew up to bigger size. So ones clearance more then 0.02 mm oil will go to that area and next bearing will have more oil, so it lasts longer. This is my expirience, I might be wrong.
Everybody facing the following. One front bearing going down-there is oil dripping from front bearing and it is because shaft is not centered during the work ( bearing is lose more then 25 micron ( C3-C4)). So clearnace is greater then 0.02 on of the side and oil escape to bearing and further. Ones bearing changed, you centered cranck back and you rearrange clearnace setting back (close to inital)-oil stop leak.
Now, what to do to prevent-replace bearing before it is gone. When-I have no idea, it is depepnd on fuel is used-better lubrication formula-longer life, other factors involve too Which fuel?-well, everybody like what they are using. I like O'Donnell-his latets lubrication formula working much better then everything else for me.
Often you change bearing is better, doesn't mean every tanks, but at list every 2-3 gallons.
If you don't change bearing on time-shaft will worn out seating place inside the crancase and then you can face air leak, which will bring to unstable idle, lose of power etc.
Edward
Ed, thanks for the info. When you're referring to the 0.02 mm clearance, which is this? Side to side or is that axial in the same direction as the shaft?
Anyway, I notice that for the main ceramic engine bearing, the crankshaft goes in real tight ! Almost impossible to get the shaft to go in fully into the ceramic bearing. Tighter than what a brand new normal Novarossi main bearing would give... Is this the tolerance you're talking about? Is this normal for ceramic bearings?
Also, after installation in one of my engines, it seems that the distance between the two bearings are slightly further apart so much so that when you tighten the flywheel nut, the crankshaft gets slightly difficult to turn. Almost like there's some drag ! It seems like the ceramic bearing does not want to sit futher into the crankcase which makes the distance between the two bearings further apart. Do you experience this?
Sorry for the many questions.
