KX500 top-end rebuild, version 1.6 by John hallbergs

[Sandblaster]

The complete beginner's guide to KX500 top-end rebuilds.

This is an instruction how to do a top-end rebuild on a KX-500. Most pictures are of my own bike (1989) during a rebuild spring 2005. Some pictures are borrowed from the Internet. Credit should be given to Doordie for most of the tuning information and the KXRiders forum for random nuggets of information.

I hope some of this information will be useful for you when you are rebuilding you cylinder, my KX500 works like a charm after following these instructions. Should you want to contact me (or Doordie), check in to the KXRiders forum.

http://www.hallbergs.net/kx500/

[Sandblaster]

It was pointed out to me that I do not have a proper installation vid for a complete top end assembly.
True... What a job that would be for me

In short, here is what I do.
Turn the lights on.
Turn the radio on.
Clean my work space.
Clean my assembly tools.
Make sure the service manual is handy for torque specs.
Check, and double check everything before and during assembly.
Makes sure the studs are good, mating surfaces clean and flat, police up all the fasteners, cir-clips, ect.
Check crank for side service clearance… I actually do this when I take the engine down but it does not hurt to double check.
Clean, polish, and clean some more.
If the piston does not have the lubrication grove in the wrist pin holes, or cross drill oil holes, I drill my own holes and polish the lead in to the wrist pin.
I use assembly lube on all moving parts but 2T oil is fine as long as you start the engine fairly soon after assembly.
Check the piston OD to Bore ID for correct clearance.
Check the ring end gap and clearance as required.
Assemble exhaust valves… you have no worries there.
Put the piston onto the connecting rod, lubing the wrist pin, cir-clips, and bearing.
Lube the cylinder and ring, or rings.
Mark the side of the piston as to the location of the ring pin or pins.
It helps to make sure you have the ring gap at the correct location as you are dropping the cylinder over the piston.
Carefully drop the cylinder onto the piston making sure the ring end gap stays where it should..
It helps to have a piece of wood dowel under the piston skirt that goes across the cases to hold the piston up as you are dropping the cylinder onto the piston.
Don’t force anything… gentle nudging or palm taps is all it should take unless you have other issues to address.
Attach exhaust valve linkage..
Gently rotate the engine over to make sure the crank and piston move easily.
If there are catches or glitches.. back up and examine everything again.
Torque the cylinder down to the specs in the Service manual and red loctite..
Check the rotation of the crank assembly again to make sure nothing bound up.
Put never seize on the mid section of the studs, not the threaded area. This is to prevent premature rusting.
Install the head using the specs in the Service manual with the criss cross pattern and red loctite.
I torque at three torque specs to insure a even torque on all the studs gradually upping each pass to a higher setting until I reach the factory specs.
Gap and install the plug.
Clean up the tools.
Clean my work space.
Start the bike up and run a couple of heat cycles.
Take it for a couple of easy rides.
Turn the radio off.
Turn the lights off.
Then let her rip..

I’ve probably missed something but that is the basics that you likely already knew.