Precis wrote:
The usual cause of a part needing to be replaced whenever it or its environment are disturbed is that they are expected to distort or be damaged during dismantling: witness the pretty standard requirement of replacing big-end bolts - having been torqued up to their operating tension and then released, the bolts cannot safely be used in the same context again, as they stretch during the initial torquing.
Thus I'd venture that the skinnier bearing is under-strength by dint of it's narrower races and is likely to be distorted - however slightly - by disturbing or removing it.
Good point. That could be it, or, at least, a part of it
Precis wrote:
Why did Honda specify this "thinner" bearing? I'd take a punt on the designers being required to use existing crankcases and/or crankshaft common to other models, but needing something else (crank counter-balance weights, perhaps?) to be larger/heavier/sturdier and therefore take up more space.
That would make sense. Also, the width of the bike might play a role in it. The bike would be 4mm wider with the stock series of bearing. It could be anything along those lines but I suspect you're on the right track.
Precis wrote:
Having the 'special' bearing to be no longer available is rather poor on Honda's part: the logical extrapolation is that once a CBR125/150 engine needs to be opened up, it's effectively scrap.
Tell me it isn't so!!!!
Well, here's the thing, the bearing we apparently can't get is the one pressed onto the crank. But we can get a new crank.... I'll leave that to your imagination
My guess is that a new crank probably comes with the bearing pressed onto it...
I measured both the bearing we can get (the crank bearing that's pressed into one case half) and the bearing we can't get (which is pressed onto the crank). Both are dimensionally identical. Both have the same number of balls. Both are made by the same company and 75% of the part number from the bearing company is the same.
So, there is a difference between them, but no-one knows what it is. In my case (pardon the pun) I ordered up two of the case-side bearings from Honda. They are, after all, dimensionally identical. So I currently plan on pressing one onto the crank and one into the case. Problem solved.
But here's the thing, what is the difference between them? Same dimensions, same number of balls. Could it be that the balls are larger/smaller? I do know that bearing companies have 'loose fit' variants and 'tight fit' variants depending on the design requirements.
My guess is that to properly deduce the reasoning we would need to understand the forces on the crank and what would make Honda differentiate between left and right or view them as requiring two different bearings. One special, and one not. Even though, they actually both are.
Here's another thing...people in AUS do list the bearing on their sites along with a price (about $90 AUD!!!!!!!)
If they actually have stock on it, methinks they might be gouging on the basis that it's an oddball bearing (pardon another awesome pun!)
I do have my parts guy looking into it though. So he will call Honda and we will get an answer. This bearing is used on every CBR125 made as well as the CBR150 so this may just be, for all I know, a mess-up by Honda. Perhaps they actually have 10,000 of the damn things in stock and they are not selling them because their parts department screwed up on the parts listings....
Rest assured, at some point
we'll get our bearings on this issue (oh man, that's just too good to pass up)
In the meantime, I'm having a ball....