Kx500 Main bearing race case repair

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7/12/2018 8:03 PM

One of the case halves I have has a severly oblonged out Main bearing race from the bearing being severely worn out... I’ve seen it before where they were a loose press fit and could still be used with some minor work... but this one has probably .040in of play between the bearing and the race... is it possible to have someone machine the old race out and machine/install a new race? I’m pretty sure you could find the center of the hole from the crank seal bore... if anyone has any input (other than buy a set of cases) it would be greatly appreciated...

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7/12/2018 8:50 PM

I would take it to a machine shop and just throw some ideas around with them...

I would think that if you found center you could weld/add material then massage it to what you need, but I maybe just taking out my ass

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7/12/2018 9:51 PM

I think a bushing repair is possible. Contact Tom Morgan Racing, he’ll know what to do

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7/13/2018 2:51 PM

Go on kxriders.com......there is a wealth of info on he site...there arę ovesized mail bearings, I think.... Honda bearings, the cases can also be repaired by a motorcycle specific machinę shop.

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7/13/2018 7:21 PM

You would need the bore welded up and remachined. The only problem i see is having a place to pick up the center of the bore. If its oblong the machinist wont be able to zero out the center. You might be able to put the other half on with the dowel pins installed between the cases and zero off the opposite side of the bore. Im not sure if thats accurate enough but worth a shot.

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7/13/2018 8:39 PM

kb228 wrote:

You would need the bore welded up and remachined. The only problem i see is having a place to pick up the center of the bore. If its oblong the machinist wont be able to zero out the center. You might be able to put the other half on with the dowel pins installed between the cases and zero off the opposite side of the bore. Im not sure if thats accurate enough but worth a shot.

I’m pretty sure I can find bore center from the crank seal bore... I believe that would have the same center as the main bearing... I have some calls out to machinists right now so I can get some input on what they think they can do...

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7/14/2018 6:17 AM

kb228 wrote:

You would need the bore welded up and remachined. The only problem i see is having a place to pick up the center of the bore. If its oblong the machinist wont be able to zero out the center. You might be able to put the other half on with the dowel pins installed between the cases and zero off the opposite side of the bore. Im not sure if thats accurate enough but worth a shot.

Paul_Pitzonka wrote:

I’m pretty sure I can find bore center from the crank seal bore... I believe that would have the same center as the main bearing... I have some calls out to machinists right now so I can get some input on what they think they can do...

Seals wont be accurate enough to zero it out either.

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7/14/2018 10:29 AM

I have fixed this sort of problem two ways;

One, machine a bearing sleeve for the case then press and peen in place.

The other is to go with a bearing with a larger OD and machine the case to accept it.

Any decent machine shop should be able to do either of these.

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7/15/2018 4:16 PM

Joko wrote:

I think a bushing repair is possible. Contact Tom Morgan Racing, he’ll know what to do

Thank you... he knew exactly what I was talking about said he’s fixed a bunch of them... just machines the inner race and installs a larger bearing... compared to everyone else I’ve spoken with his fix by far seems the most simple and best fix in my opinion.... will post photos when I get it back

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