What piston to use?

[dezracer]

Does anybody recommend a certain brand of piston?  I'm doing a top end on my kx500 and was going to use a Wiseco Pro-lite for the new piston.  I know the piston effects the characteristics of the motor.  I'm strictly a desert racer so does anybody have any suggestions.

Cool site, this is my first post.

[Paul]

I like Pro-X myself. I've had nothing but bad luck with Seize-Co pistons, lots of people have had good luck with them also though

[mikesmith]

I run Wiseco no problems,just let it warm up when its cold.

[KXKID]

Hey Dezracer - that is a GREAT first question to ask - REALLY!!!
I redid my 2000 KX5 last fall.  When I pulled the top and examined the stock piston (had never been down before) I noticed that it had been stamped "B" on the top.  I had redone my KDX250 back in the mid 90's and had run into this designation stamp before.  On my KDX I went ahead and ordered a Wiseco for it and was VERY unhappy to hear it piston rattle after installing the BRAND NEW piston!!  I went ahead and rode out the season on it (another 1500 miles), and sold it and bought a different bike.
Bescause of this experience I did some background work on exactly was/is a "B" piston.  Come to find out, there is a piston standard that uses A, B, C, or D for a SIZE designator (I am sure you could "google" this and find out the same info!!).  Once I found that out I called Wiseco and found out that they size to the smaller designator (I believe it is "D").  I called Kawasaki direct and they told me that if I ordered a "stock" piston for my 5 that I would have to take what I recieved from the order - yes, A B C or D!  I then looked in a Marshall Book (found at most bike shops) and looked up pistons, found Pro-X to be the ONLY company offering the "B" piston.  I went with a Pro-X.
I have a REAL close riding bud who also has a cross country KX5 (our bikes are street legal so we can ride EVERYWHERE - ANYTIME!).  He said I didnt know what I was talking about and went ahead and ordered a Wiseco at the same time I ordered my Pro-X.  We "miked" our new pistons and he was SHOCKED to find a 3 1/2 thou diff between the two!!  To some folks that may not sound like much but to him it did (me too)!  He sent the "sieze "o" matic" back and built with a Pro-X too!
Now, here is another tidbit of info.  As I was cleaning my new piston (doesnt everyone clean a new piston before install?) I noticed what appeared to be a crack directly under the wristpin holes on both sides (I have an extra Pro-X piston on the shelf with the same markings - if you wanna see what I am speaking of let me know and I will e-mail a pic to you!).  My Bud  recieved his and his had the same markings in it.  REAL close examine under a magnifiing glass refealed what appears to be a silicon buildup between the aluminum cast - kind of shaped like a water droplet line. I was VERY concerned about this but now have over 5000 miles on the piston and its doing GREAT!!  
Its always something aint it!
Anyway, hope this helps you!!
the KID  

[gowen]

I've run Wiseco for the last 10 years in my bikes. Never had a seize due to the piston or clearence, just measure the gap and make sure the cylinder is fresh before installing a new piston. I could go on for hours on why Wiseco has been good to me, but to save the trouble I will just let you know Wiseco has been great for me.

[91kx]

I've also rebuilt my last 3 mx bikes with wiseco and have never had any problems.

[mikesmith]

Wiseco Im sure is the only forged piston, so it expands more and is stronger than cast.Cast pistons are normally heavier and weaker than forged but expand less,so they have a  more consistant fit hot or cold.

[dezracer]

Thanks for the input.  I think I'm going to run the wiseco.

[Rick]

Good choice.

Rick