top end rebuild

Sep 11, 2000
When doing a top end rebuild what exactly do you need. I am planning on getting a standard Wiseco piston kit that includes a piston, rings, wristpin, and circlips. and I am also getting a cometic gasket set. are there any special tools i need other than a torque wrench? by the way the bike is a 2000 KDX 200 on its first rebuild. Thank you.
Dec 10, 2000
You will also need a wrist-pin bearing, and an exhaust donut (the inner pipe seal). I also replace my pipe springs when I do a top-end, but that is just a personal preferance.

As for tools, you should have a micrometer and inner-caliper to check the bore (or you can take it to a shop to be measured), and a set of feeler gauges to measure and adjust the ring end-gap before assembling the engine. It is also a good idea to get a ball-hone, but you can use a scotch-brite pad, as well.

Make sure you disassemble the power valves to check and service them.

I use Weisco's, and have no problems with them. However, with a forged piston, you MUST break it in properly, or there is a high risk of seizing the top-end during break-in.

1992 KDX 250-FMF porting,two-stage power reeds, Fatty pipe, Power Core silencer,titanium rod,Wiseco Ultra-lite, Pro-Action suspension...Oh my Gawd, they killed Kenny!


dirtbike riding roadracer
Mar 28, 2001
a set of hammers, a set of chisels, 1 med size pipe bomb, lots of silicone, a couple cresent wrenches, some screw drivers (all flat blades!), a hack saw (for the ring end gap), some steel toe boots and a case of beer!

oh yea, lots of rags (the real furry ones), and throw that book in the trash! Bring over the bike and case of beer an I'll show ya how it's done! oh oh I forgot the pipe wrench for getting the piston back into the cylinder and the 80 grit sand paper for honing the cylinder! be sure to rub the head on the cement floor to surface it!!!

PS. it's not hard, read the book & don't break the governer shaft pin.

Sage Wilkinson, KDX Link 1

Nov 14, 2000
be careful for the actuation shaft that runs up from the cluch (it is reverse thread, do not over torque it) do not over tighten it or you will have a problem with the pin falling off.

Fred T

Mi. Trail Riders
Mar 23, 2001
I appreciated your humor! :)

Oh Oh two twenty


Damn Yankees
Nov 19, 2002
Is that Exhaust donut thing MANDITORY? Does it come in a top end gasket kit? Would I need to replace it in a year and a half old bike (1st top end)? And what is proper break in for a KDX wiht a Wiseco piston? Do I go by the book, which is warm up throuly at idle, ride for 10 min. gradually, and easily, Completely let cool. re warm up, and ride for 20 mins nice and easy, then let cool completely. then let warm up again, and ride for 30 mins easily, then let cool. Change oil, then its ready to be pounded. Does this sound right?

May 31, 2003
That's good info to know. Who has the best prices on Wisco kits that you guys know out there? I'm looking for mail order for '99 KDX 200.


Damn Yankees
Nov 19, 2002

Pro lite Piston Kit - $84.95

Cometic Top end gasket kit (comes with everyhting including kips) - $28.99

Wrist Pin Bearing - $12.99

Shipping $7

This is the best deal I could find, and I did my homework on it.