Can I reuse this

[waldo177]

I'm in the process of rebuilding my 96 kdx200 because the main bearing came apart. My question is can I use this right side case or will I need to replace it?

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[Tedh98]

Are you concerned about the scratches or is there something else I am not seeing? Unless there is other damage the case will be fine with a new bearing.

[Julien D]

as long as it is not cracked anywhere you will be fine.

[waldo177]

Thanks I didn't see any cracks, I had someone tell me that it would make it run bad if it wasn't smooth

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[Jim B]

Kind of a weird failure. I've seen plenty of seized crank bearings, but I've never seen one that flew apart. It's even a Japanese bearing...

[TheRadBaron]

I doubt that a bit of roughness in that area would make any difference at all in how the bike runs. I guess I'm not an expert in 2-stroke crankcase flow, though. If I were you I'd probably just smooth it out a bit with some emery cloth and call it good.

[KDXGarage]

run it

You are not racing for the championship, are you?

[waldo177]

No I'm not running it for a championship but I would kick myself to put it back together and it not run right because of this.

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[MotoArts]

I recently redid a Suzuki DS80 with the same bearing failure. Cases weren't gouged, but it did suck one chunk up into the transfer port and trashed a brand new standard bore Wiseco (installed by the previous owner).

Put 'er together and run it!

[Tioli]

Running right will not be the issue as there is no designed flow through for that area. You are supposed to get some oil running down the sides of the barrel and into the holes to lubricate the bearings. As the piston goes up and down you will get positive and negative vacuum in the area which will bring some oil to the bearing. This process will cause a lot of the oil to fall out of the fuel and make its way to the bottom of the crank which will help lubricate the bearings. At the end of the day the scratches will have little influence on that process as it’s going to happen even if you have shaved a little off and roughed it up.
The only thing I would be concerned with is:
Is it rough enough that at some flakes may want to flake of at some time? If so give it a clean-up.
Are the scratches deep enough to cause a structural issue? Have a good look at them, see what’s on the other side to determine how thick the material is, any support castings etc. The bearing is held in with a cast in steel liner so that in its self is very strong so you should be right if the scratches aren’t that deep.

[waldo177]

After pulling the bearing this what I found. I have taken some emry cloth to it but port is kinda damaged down where it feeds the bearing with oil. Will this cause to much positive or negative vacuum?

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[waldo177]

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[Tioli]

I don't think it will have any effect. If you imagine the bearing in there the area where the oil comes out is the same so no change. Just make that slot smooth so it can run/blast all the way down.

Because the photo is squire on I have no depth perspective so can't see your new ridges (don't look that bad).
There is one line around just out from the steel liner that would draw me in for a close look. I would pick a spot and dig at that by taking little shaves of with a dentist tool to determine where the base is (how deep is it).

[Tyl3r]

I would say that as long as the bore that the outer race sits in isn't gouged or cracked and the bearing can sit perpendicular with the shaft when its pressed all the way into its pore, its all good. If any of those gouges on the bottom are high enough, the emery cloth should be enough to take them down and allow the bearing to sit nice and flat down in there. I don't know what the main bearing looks like, so I don't know if this is entirely true or not, but I know that with bearings of that size or larger, sometimes manufacturers put a little groove in the inner or outer race of the bearing to help get the last ball in between the races. Perhaps that could be part of the reason the bearing came apart? But I don't know, those look like pieces of a cage, maybe it didn't. Something else come apart in the motor that could have found its way in there?

As for the oil flow port, I wouldn't be concerned. All of my advice is based on working with 60 Hz rotating equipment. With our equipment, the flow passages designed like those are just there to flow oil through. If any certain level of pressure was involved, or a specific flow rate required, it would be a machined feature rather than a cast feature. Just my thoughts, take em with a grain of salt, I've drank a couple beers this evening lol good luck with the rebuild. Getting ready to take mine apart in a month or so, hoping I don't have to tear into the bottom end!

[waldo177]

I don't think it will have any effect. If you imagine the bearing in there the area where the oil comes out is the same so no change. Just make that slot smooth so it can run/blast all the way down.

Because the photo is squire on I have no depth perspective so can't see your new ridges (don't look that bad).
There is one line around just out from the steel liner that would draw me in for a close look. I would pick a spot and dig at that by taking little shaves of with a dentist tool to determine where the base is (how deep is it).

They are not bad at all my main concern is the port that feeds oil to the bearing. Thanks

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