TOPIC:

So, I've got my motor apart to swap out a bent rod, and while I'm looking everything I've noticed that one of the bearings for the secondary shaft (the one directly behind the crankshaft) is pretty jacked up. Now, I've looked up part numbers, and the one they give is, I believe, one of the two or three possible bearing sizes for the connecting rods. Is this right? Does the secondary shaft only take one size bearing? Or am I going to have to measure the shaft journals and get a correct size, like with the connecting rods? At $50 a bearing set, I don't want to be wrong on this.

You've lost me. I just looked up the secondary shaft bearings on Partzilla and the large roller bearing is 92045-1015. it should have a stamping # on it "6009". There's also 2 needle cage bearings in the secondary driven gear part #92046-1014 and they should have a stamping # on them "HK2520." There's no alternate sizes for this bearing.

92028-1049 is one of three conrod "bushings" (should be called a plain bearing) and is only used on conrods according to Partszilla. it has a green marking.
92028-1051 is an alternate and has a brown marking . It's probably first under grind and could be for .005" or .010 under sized crank throw journal size.
92028-1050 is an alternate and has a black marking. This is probably second under and could be for .010 or .020 undersized journal.
Usually on most parts listings they will tell you 1st under or 2nd under and the journal diameter it fits but Kawasaki just seems to reference "color markings"

Here's the bearing ("bushing") in question.

Now, Partzilla list the part number for this as 92028-1108, and that number only. However, that number is ALSO one of the three sizes of main crank bearings (not connecting rod bearings. My mistake.). If that is the only bearing that will fit, all the better. I'm just wondering, since there's a procedure to fitting the correct size bearings for both connecting rods AND the crankshaft, if there was such a thing for the secondary shaft as well.

For the record, the manual says nothing about sizing the bearings for the secondary shaft. Just a, "if worn, replace".

I found in my manual on page 190 a reference for the secondary shaft. Journal diameter Service limit is 39.96mm so I'm guessing the new journal diameter is 40.00mm with a .04 mm wear limit which is a .0015" (one and a half thousands of an inch) wear limit. It also states that the bearing insert journal clearance is .11mm which is .004". So if your journal measures within spec you should be able to just buy new bearings and pop them in.

If I were doing it, I would drop in the new bearings and plastigage the journals.www.plastigaugeusa.com/ It would require reassembly of the crankcase halves and torqueing then disassembly and measure the plastigage.

I would also try to figure out why your journal bearing got knackered. Low oil flow or somebody ran the bike with low oil which would have increased the oil temp. Basically the bearing journal typically is a copper backing with a babbitt facing. Babbitt is a type of lead (soft with a low melting temp) Doesn't take much to screw up a Babbitt bearing if it's not flushed with oil during running. I would check the oil feed circuit. I saw another post a while back where someone found metal debris in the feed ports to his main journals. I'd be stripping the case halves of everything and going for a good cleaning and blowing out all of the feed lines within the case halves before I would continue here.

Thanks for the info. As far as the bearing goes, there's no copper showing, so that's something. However, the bearing surface is rather rough and peeling. There is quite a bit of crap in the oil passage on the shaft as well.

The motor has 40,000 miles on it, and the PO was a fan of red RTV instead of gaskets- I found a bunch of it stuck in the oil screen. This may have been part of it. Still, apart from this (and the bent rod, which is why I split the cases in the first place), the motor looks pretty good.

Post a pic so I can see what you're on about. Sometimes looking at the Babbitt will tell you if it's from overheating or if it's from scraping from debris.