Complete KX500 top-end rebuild instruction here!

[ebers17]

The instructions are great, very helpful, except for one part.  I'm having a hard time getting the worn out pins on the power valve, i want to switch them 180 degrees like you said, but how do you get them out??? any help would be great, thanks, keep up the good work!

[Brett]

I ust put a pin in the vice and taped the valve off with hammer.  instead of reusing the pins go to a bearing store and buy some new ones they cost stuff all.

[John]

Ebers17,

These buggers are hard to get out, at least the first one. The second one you can ‘push’ out from the opposite side. If one pin is really stuck, try the other side. Maybe that one comes off easier?

If they both are really stuck, use heat. Warm up the valve - not the pins. Don't warm it up to welding temperatures. High temperatures tend to change the characteristics of metal.
While the valve is warm use the same technique as before and see if it comes loose. Be careful with the hammer as the warm valve is more likely to get dents…

If you are replacing the pins, youcan use drill steel (cut off a drill), or steel with similar hardness.

//John

[kajendog]

Thanks to you guys for this effort in putting together this rebuild guide. It is a great reference to have on hand, especially the power valve Info.

[John]

FYI: I have updated this instruction today and revised the squish and the KIPS valve sections.

Nothing revolutionary, just some clean up's.

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

//John

[eprovenzano]

Can I safely assume, that the rebuild of the legendary KX500 would be similar to my KX250?  I plan on doing a top end rebuild on my 99 KX250 in the early spring.

[davidvak]

VERY IMPRESSIVE !!!!!!
THANKS A LOT !

[raredesign]

I don't get the whole ballbearing idea for valve closing

[redlined_KX500]

Those ball bearings go between end of KIPS actuating rod and end cap to control over rotation. I found mine at a bicycle shop. Can't remember exact size but it's listed in the thread for fixing that particular problem.

[wreck-n-roll rik]

Great info and helped me alot tonight.  Now tomorrow I'll have to put it back together after I clean it all up, found a leaky headgasket - Walls look good, piston good - have new rings and gaskets.  Thanks, hope if I have problems getting it back togther you guys are around.

[markus18]

Well done!  Thank you!

[KTMEXC125]

i have some questions on modifying a new piston. do i file the top edge also? of just the bottom edges and the edges around where the wristpin is