I have a set of new OEM S10 bearings and seals my buddy at the dealer gave me when I "thought" my S10 needed wheel bearings. They are double sealed and I could give you the bearing numbers to cross reference if it helps. Korean made if I remember correctly. For my Strom I bought NTN bearings locally that were double sealed and seemed to hold up well.
But, I have a question that has been checked on another bike and sort of double asked on the YST forum. On my old Strom, if you picked up a wheel by the inner bearing races and spun the wheel, the bearings would turn very smoothly. When I did this with my S10 wheel, the bearings felt tight and the inner races would spin on my fingers instead of staying stationary. I found out by asking around at YST, that the S10 bearings feel tight until the inner races are pushed against the collar (if this makes sense). If I use my thumbs and push inward on both bearing inner races to keep them from rotating and roll the wheel on a floor, they feel smooth (this is not easy to do by the way). I am not sure if this is what Yamaha intended or if the collar may be too long or the wheel machined wrong where the bearing OD sits. Another S10 wheel seemed the same as mine.
I went so far as pulling my calipers and mounting the wheel with the original bearings, spun the wheel and I think they are good. It makes it hard for me to judge the bearing wear though. I discovered this at 18,000 miles and it seems the same at 24,000 miles. I tossed the new bearings in the spare parts box and am running the old ones for now.
Your thoughts RCnNC?
I'll be honest, I don't think I've ever tried to turn the bearings with my fingers. When I check the bearings, I just pull the wheel from side to side to see if there's any play in it. I have taken the wheels off to change the tires, and when I do, I balance the wheels in one of those Marc Parnes balancers. Those have cones that fit inside the bearings to support the tire while it's being balanced. The balancer looks like this:
The whole axle, cones, and wheel rotate as a unit when the wheel is spinning; the unit sits on those bearings at each end of the axle, and it rotates on those bearings. The cones don't exert any inward pressure on the bearings the way a tightened axle on the bike would. My guess is that the inner races aren't moving while the wheel is being balanced, or else the axle of the balancer wouldn't be rotating on those bearings. So I'd guess if I tried to spin the inner races by hand, I'd probably experience the same tightness you did. If they weren't tight, then the wheel would rotate around the wheel bearings when it was on the stand, and the whole unit wouldn't be rotating on the axle of the balancing unit. Hopefully, that makes sense.....
If you have that set of OEM bearings, it would be awesome if you could read the numbers off them (or even take photos of them), so I can see if the numbers match up with what's available from bearing supply houses. There should be three different sizes of bearings in the set. The front bearings and the rear wheel non-drive side should measure 22x44x12. The rear wheel drive side should measure 22x50x14, and the bearing in the clutch hub should measure 25x47x12. I believe the front bearings and the rear wheel non drive side bearing should have a number something like 60/22 2RS, the rear wheel drive side should be something like 62/22 2RS, and the clutch hub should be something like 6005RD or 6005 2RS.
Thanks, I really appreciate the help!