Maintenance & Technical > KX500 Original

bottom end

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gwcrim:
Can I determine the condition of the bottom end by wiggling the rod around?  How much play should there be?  Side to side?  Up/down?

Rick:
Actually, don't worry too much about side-to-side play on the big end bearing, worry more about the play as you "rock" the rod.  The distinction is critical, as it can mean the difference in a running bike and not running, and if you spend a lot of money for nothing.

Grab the rod at the top where the wrist pin bearing is inserted.  While holding the rod as straight up and down as possible, try and pull the top of the rod down towards the water pump, and then down towards the other side of the motor.  While you should have a little play just to compensate for heat expansion, you shouldn't have a lot.  

A good way to measure the play is by sitting a trisquare on the base gasket surface where the cases split so that the ruler is standing parallel to the rod like a knife edge, in the center of the top of the rod. Watch as you try and pull the rod downward, noting the amount of movement.  (I hope I have explained this well enough to make sense.  If not, just let me know and I'll try again)  If you have about 1/8 inch, you should be OK.  Any more, you might want to think about installing a rod kit.

Let us know what you find out.  Good Luck

Rick

gwcrim:
That seems to check out OK.  Less than 1/8" play at the small end, so to speak.

I should have sent you the $35 I wasted on the Kawi manual.  That thing's a POS.  Thanks, Rick.

1alldave:
The real issue with KX500s that are revved hard and often is the condition of the case races. They wear out and the bearing gets sloppy in the case. When this happens you will feel excessive vibration and a shudder through the frame when the revs drop after a free rev with the bike in neutral. An easy way to check is to remove the ignition cover and grab the flywheel and try to wiggle it vertically. It is normal to feel a slight amount of horizontal play, but you should not get even a slight click up and down.I had this problem after 3 seasons and replaced the cases.There is place back east that can sleeve the races for a much lower cost, but I found this out too late.

Rick:
Wow, never heard of the crank bearing wearing out a case, but with all the vibration, it makes sense.  I usually have the crank trued which should help eliminate this problem, but probably don't keep my bikes long enough to develop this problem, but certainly good to know.

Thanks for the input!

On the Kawasaki manual, I've never even looked at one, but have heard that they do not provide very much information.

Rick

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