Well, just ran into an interesting crankshaft bearing issue.....
The OEM parts catalog lists the crankshaft bearing as two different numbers, one that's pressed into the case and one that's pressed onto the crank.
I originally tried to buy them from Honda. Honda says that the crank bearing is not available (discontinued). You can, however buy the crank bearing that's pressed into the case.
Dealer says, don't worry about it as it shows up in the parts listing as a 6207 bearing. So, I go up to the bearing store and special order some quality NTN (Japanese) bearings. I didn't look at them very closely when they came in and pressed one onto the crank and one into the case.
During a trial fit I found out the crank is not sitting deep enough into the bearing. After a lot of head scratching I pulled the 6207 bearing and measured it - it's two millimetres thicker then the stock bearing....
The 6207 bearing, which is what the OEM Honda parts book calls it, is 17mm thick. The Honda 6207 series bearing, for this bike, is 15mm thick......and that explains why the crank won't sit properly....
The OEM bearing is a 6207 series bearing made by NTN. After exhaustive research it seems that this bearing does not exist in the 'real' world - it only exists in the Honda world. This, as it turns out, is because the bearing is specially made for Honda by NTN....so it cannot be sourced anywhere else.
Call up a bearing engineer, give him the dimensions of the Honda 6207 bearing and you will draw a blank. It does not exist.
OK, so we can't go to the aftermarket for this bearing. But, Honda also declares the crank bearing as discontinued. This means you can't go to the aftermarket or to Honda for the crank bearing!
I seem to have lost my bearings.... Dimensionally, the crank bearing that is pressed into the case it identical to the crank bearing that is pressed onto the crank... The case bearing is available, the crank bearing is not.
What does this mean? It means if you buy a 2014 CBR125 and cook the crank bearing you are out of luck - at least as far as the dealer and aftermarket is concerned.
Even though both bearings are dimensionally identical the crank bearing carries a different part number. Why is that? I can think of several reasons;
The crank bearing is either a precision bearing or it's a 'loose' bearing or it's a 'tight bearing'. God only knows what the story is on the crank bearing or what makes it 'special' I do know that both bearings are specially heat-treated over and above a standard 6207.
The Honda service manual specifically states that whenever you split the case ALWAYS replace the crank-side bearing. Why is that? Is that particular bearing subjected to more or different load then the crank's case bearing?
What makes the crank bearing special, to the degree that it merits it's own part number and must always be replaced when the case is split? Why does the Honda parts manual designate that bearing is 'special' ?
Aside from that, what is a person to do? If you cannot get the crank-side bearing what do you do? Buy two case-side bearings and install them because they are dimensionally identical? That's the work-around that I'm going ahead with but I don't like not knowing why the crank-side bearing is 'special'.
Either way, I wasted $$ on two 6207 bearings and the time to install them....
only to replace them (again).
What the heck is so special about the crank-side bearing that Honda insists they have to be replaced every time the case is split and that causes them to have a special number?