Bearing substitutions

I'm assembling a kz650h1 motor that's been sitting for a long time, upgrading where I can with Zephyr parts. Before I get too far I wanted to go ahead and change the secondary shaft left side bearing. On the Zephyr secondary shaft it is listed as a 601b6025 bearing. A little looking has me thinking it's a Nachi 6025 c3 bearing. The bearing in the case says NTN 6025. If I just order the Nachi bearing off eBay it's half the cost of the genuine Kawasaki part but if it's the exact same thing I see no reason not to. So for the sake of double checking with the experts: Kawasaki uses the same Nachi bearings I can go order through any bearing wholesaler, right?

You might want to look up the data sheet for the stock bearing (if you can find it) and compare the load ratings from the OEM bearing with those from the bearing you are considering. In particular, the dynamic load ratings. Also, make sure you match the C3 clearance rating, which it seems you have done. I think that Nachi bearing should be fine. Just be sure to get an the type without seals or shields. When you install it in place always be sure to not damage it as well.

Thanks, but that isn't exactly what I'm looking for. I assume Kawasaki outsources their bearings, what I want to know is if anyone knows where they get them from and if I'm looking at the correct part through a different source.

aplaceinspace42 wrote: Thanks, but that isn't exactly what I'm looking for. I assume Kawasaki outsources their bearings, what I want to know is if anyone knows where they get them from and if I'm looking at the correct part through a different source.

What? That's a totally different question than your first question.

Bearings are commodity items. Companies like Kawasaki may purchase them from NTN one year, and Nachi the next. It depends on price and supply. When purchasing a replacement, even if you purchase directly from Kawasaki, there is a very good chance that the bearing you get will be different from the original. When rebuilding my 750 I bought a FAG bearing from Amazon www.amazon.com/gp/product/B005M3ET8E/ref...00_s00?ie=UTF8&psc=1 To be honest, you can get a bearing from Kawasaki for the same price so I'm not sure why I even bothered with aftermarket.

One thing you may want while the secondary shaft is out is to replace the damper rubbers in the primary drive sprocket and rebuild your clutch hub. Those things develop a ton of slop as the rubbers shrink. Changing them was one of the best things I did for my bike.

Where did you get your damper rubbers from? I've read that there are modern replacements being made but haven't found a source.

aplaceinspace42 wrote: Where did you get your damper rubbers from? I've read that there are modern replacements being made but haven't found a source.

I bought damper rubbers for the secondary gear from a dealership source (Partzilla). Have a spare set even just in case.

I got the clutch dampers from this guy ... jnsummer AT hotmail.com
He is in Australia and makes the dampers from neoprene.

There is another guy named Turbosteve selling Viton dampers over at 750turbo.com. Check this thread to find contact info... www.750turbo.com/forum/viewtopic.php?f=4...nt+Warning&start=360

Excellent, thank you.
I've read up on rebuilding the clutch by bolting it back together after drilling out the rivets. Is this what you've done? I've got access to a press and was wondering how hard it would be to rivet it back together.

aplaceinspace42 wrote: Excellent, thank you.
I've read up on rebuilding the clutch by bolting it back together after drilling out the rivets. Is this what you've done? I've got access to a press and was wondering how hard it would be to rivet it back together.

A friend welded mine. I think that's more secure than welding.
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99.9% of all bearings are standard. Usually you just need to know inner and outer diameter. BUT!!! There are different quality grades and you don't want to replace the bearings a few months later again.
Price for high quality bearing can be 5-7 times higher than low grade.