New KDX guy - Maryland

[B737driver]

http://www.kdxrider.net/forums/viewtopi ... 34#p165701

My vote is OEM

[KDXGarage]

I searched the internet for a while, which led me right back here. ...

http://www.kdxrider.net/forums/viewtopi ... 77&t=18234

I think it is OEM. About 9 out of 10 of us with an opinion one way or the other will suggest that you swap out OEM for a different one.

[BamBam]

As one more clue - I have this symbol inside the piston. It would seem incredible that a 20yr old dirt bike still has a stock piston. But I guess anything is possible. Or that a piston change may have been done with yet another OEM replacement?

[BamBam]

And WOW - this post also references this exact marking as stock. http://dirtrider.net/forums3/threads/19 ... on.127641/
AMAZING! You guys saved the day. I would have thought it impossible.

I have never ordered a piston before. Motosport has a Wiesco on sale. Do I use the same needle bearing? Anything else I need to replace other than piston, rings, clips?

Ebay has a bunch of them for under $90, that appear to be new. But strange -- they say for a KDX220 years 98-05. Mine is a 1997. Is there something different between a 1997 and those other years?

Same for the web site for Wiseco and Wossner. They list KDX220's as ranging from 1998-2005. But my frame ID definitely says 1997

[KDXGarage]

They are the same.

Gasket kit

Piston
Rings
Small end bearing
Two circlip
Piston pin

Check to see what comes with the piston kit.

Look on Wiseco .com to have the most accurate inventory

[B737driver]

If you order a top end kit, from eBay for example, it will include all that you need. Some come with the gasket kit as well. In the mean time...clean the kips and reinstall per the manual...inspect and carefully remove any gasket material off of the engine and cylinder...watch a few videos about how to install the circlips (do one side, then install the piston pin, then attach it to the rod, then the other circlip)...COVER THE ENGINE BOTTOM END WITH RAGS WHEN YOU ARE INSTALLING THE LAST CIRCLIP...reinstall cylinder...get ready to ride with the added security of a new piston

[BamBam]

The "Piston Kits" I am seeing all come with the piston, two circlips, piston pin, and rings. None come with the small bearing. Is the typical practice to reuse the bearing?

The main pistons available are Wiseco and Wossner. From reading on line the Wiseco is lighter and not sure if I want that, and the Wossner has a single ring, not sure if that is good either. At this point, I am starting to worry the bike may never run again. My wife says there is less and less of it each time she walks by!! Ha!

If the bike had good compression, and I am changing the piston just for piece of mind, do I put an "A" piston back in to replace the "A" piston I took out?

[B737driver]

I have never purchased a top end kit that did not include the wrist pin bearing. I have always used Wiseco with no issues. I have no experience with Wossner. Here is a link to one that has all you need. Am I missing something?
http://www.ebay.com/itm/WISECO-TOP-END- ... HA&vxp=mtr

Sounds like you are still wondering why you are replacing it. Here is what KDX legend Jeff Fredette has to say about it. If you haven't heard of him do a little research and you'll find that there are few that know as much or have done more with the KDX. We aren't making this stuff up.
http://www.dirtrider.com/features/onlin ... dx_200_220

You could always purchase a gasket kit and put it back in. FWIW

[BamBam]

B737 - I am totally on board with replacing the OEM piston because of its reputation of shattering. No problem there! I was just having a hard time grasping how a dirt bike goes 20 years on a stock piston, bad reputation or not. Back in the day we would change pistons and bore bikes for 20 over, 40 over, etc.

Either way, the bike is opened up and I am not going to take any chances! It's juts been a long long time and I am rusty on ordering the right parts.

I already bought the gasket kit. The piston kits I see did not include the bearing... like this one as typical. http://www.ebay.com/itm/271218696700

Rocky Mountain has a good piston kit price AND they sell the bearing separate if needed. So sounds like I need both.

When I say take "A" piston out, I meant put the same "A" size wiseco standard 69.00mm back in...because of the plated bore with no signs of bad wear?

Sent from my SM-G900V using Tapatalk

[KDXGarage]

I don't remember them coming with the bearing.

Install the circlip opening at 6 or 12 o'clock.

You may want to measure the bite size to make sure you get the right piston, but if it had a stock piston, it should be around normal size. Letter sized pistons are available from a few manufacturers, if you want to match up clearances.