Vintage Dirt Bike Q & A

I'm finally getting around to actually rebuilding my motor for this. Got slammed with work this past year and had a lot of racing going on last year. Didn't even get to this year unfortunately. But I finally was able to get that stubborn flywheel to come off which was a nightmare. Got the cases ready to split, so I'm looking around for bearings and seals.

I was curious if the CR250 or MT250 of this year had the same bottom end, bearing sizes and all? I did a few searches, but didn't see anything that said for sure. I found a place on Ebay that has a bottom end bearing and seal kit for the CR for $70.

You can compare the part numbers on a site that has the original microfiche. I've been using this one: http://honda.woodsfuncenter.com/fiche_select.asp

That's what I ended up doing. I looked at the Western Hills Honda parts fiche. Seems that all bearings from CR, MT and MR are the same except for the countershaft bearing. The mainshaft I guess you'd call it. I don't have my numbers in front of me, I wrote it all down, but I think the MR has a smaller one. I think the CR and MT were the same though. I'll put up a chart later on here for future reference for others.

I found an eBay store, Boss Bearings, that had a CR bottom end kit that had every bearing but that one oddball. The MR has a 6304 which are easy to find as opposed to a 63/22 I think was the CR, MT number.

2 or 3 jears ago i bought there an engine bearing & seal kit for my 80 cr250.
bearings were cheapest no-name, not C3 spec where needed.
seals hat not the same spec as original, no dustlip , some were not as thick as it has to be.
all shit, never more....

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80 CR250Ra
80 CR250Ra
78 CR250R
80 CR80
82 Bultaco Sherpa 340
78 Bultaco Pursang 250 MK12
76 Bultaco Frontera 370 MK10
76 Bultaco Alpina 250
73 Bultaco Lobito 125 MK6
76 Suzuki RM125A
90 Kawasaki KX250

Well, I was hoping I wouldn't have the same experience. All the bearings are either HBC(Chinese) or no name or part number at all. I'm sending them back and just ordering the part numbers from a bearing supply place I get other stuff from. Should've just done that in the first place. Thought if I get a kit, it would be easier. At least they will give me a refund, but it's going to be a pain in the ass shipping them back and waiting for one.

Moral of the story, Boss Bearings lies. They told me all kits were Koyo, Nachi, or similar Japanese bearings.