787/800 Crankshaft Bearing Question

[teamgreen737]

Broke down my motors for inspection and noticed this center bearing can be moved left or right with my fingers on the crank axle. Is this normal on the 787 800 motors or is this bearing “spun”?

 

[etemplet]

That bearing should track "true" and smoothing if you spin it. If you push the top side to side you should not get much wiggle or looseness. If you believe the the bearing inner race is moving on the crankshaft "it is done." Might be difficult to determine what you see in that small space but if there is any wobble or roughness the bearing is done. Check all the bearings and you'll notice small differences if there are large differences that is a cause for concern. Good Luck.

 

[teamgreen737]

The whole bearing assembly will slide from side to side on the crankshaft if I push the bearing laterally and is not fixed in position.

 

[etemplet]

Deader than fried chicken. New crank needed or rebuilt from a vendor of your choice.

 

[teamgreen737]

Thank you etemplet! Is that considered “spun” in this case where inner race is no longer fixed on crankshaft axle?

 

[etemplet]

Thank you etemplet! Is that considered “spun” in this case where inner race is no longer fixed on crankshaft axle?

Well it did spin. I think more accurate would be lost the fit.

In my neck of the woods and age group a "spun bearing" referred an automotive crankshaft or camshaft babbit bearing becoming dislodged and turning in the housing rather than remain in a fixed position. Loss of oil excessive torque etc... puts a big load and babbit becomes liquid and makes a mess. LOL The babbit being soft is designed to fail rather than the housing or the shaft journal. Hope that helps a bit....

 

[teamgreen737]

Thank you for the explanation, try and learn something new everyday! I grew up racing two strokes dirt bikes, have two stroke skis, and a challenger boat! All I’ve rebuilt has been two strokes.

Just bought a 28 foot Marinette with twin Chrysler 340’s! Looking forward to learning how to rebuild them down the line.... Hopefully a good while down the line!

 

[mikidymac]

Thank you for the explanation, try and learn something new everyday! I grew up racing two strokes dirt bikes, have two stroke skis, and a challenger boat! All I’ve rebuilt has been two strokes.

Just bought a 28 foot Marinette with twin Chrysler 340’s! Looking forward to learning how to rebuild them down the line.... Hopefully a good while down the line!

Hopefully the bikes are Kawasaki’s with a name like Team Green, lol.

 

[teamgreen737]

You got it!