Piston Identification with Inspection Camera

Discussion specific to the 1995 - 2006 KDX200 (H Series) and 1995 - 2005 KDX220R (A Series) models sold in the USA
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billie_morini
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Piston Identification with Inspection Camera

Post by billie_morini »

This forum is invaluable, and it is not possible to express my gratitude to all who have contributed to it. I would like to share how it was determined whether the piston is OEM or aftermarket in my recently purchased 1999 KDX 220. I used a Digital Video Inspection Camera. (You can get the same one I have from Harbor Freight for about $85. It is the AMES 2.7 In. Color Compact Digital Inspection Camera).

The provided image shows both the “double star (maple leaf) SK letters” symbol and the numeral “2” above the symbol. These markings exist on the inside of the piston skirt near one of the wrist pin boss. The piston was placed approximately mid-stroke and the camera was inserted through the intake ports located left and right of center. It is possible to see the symbols from either of these two intake ports. The “good” image was made with the camera inserted through the right port. The “poor” image was made with the camera inserted through the left port. The “poor” image’s value is that it shows it’s not necessary to get a “good” image to identify the stars. If not for this forum, I would not know to look for these symbols.

Additional notes:
1) I didn't want to remove the cylinder head without having a new head gasket on-hand. If it was determined that the OEM piston was replaced, then it would not even be necessary to remove the cylinder head.
2) The carburetor and reed valves were removed for cleaning and jetting. Therefore, there was no additional effort required to use the camera for inspection.
3) Firstly, the camera was inserted through the spark plug hole. I did not see any numbering similar to that which Wiseco uses. However, carbon exists on the piston surface that made it difficult to even see the arrow. In contrast, it was possible to see concentrentric parallel rings in some areas. It seems like these rings exist in both cast and forged pistons, however they may be more prominent in forged pistons.
4) Secondly, it took me a good while to comprehend the features displayed on the camera video screen. Even though the "good" photo is good, a fair effort was expended to reliably locate the star symbol. However, now that it is known where it "lives", it is easy to re-locate it.

Moral:
Check the piston instead of believing what seller says. My KDX was purchased from the 2nd owner. The 2nd owner told me the 1st owner told him that the piston was replaced with a Wiseco piston. However, he admitted that he never validated this.

Subtitles to aid user search finds:
How to tell if I have OEM piston or Wiseco piston
How to tell OEM piston from Wiseco piston
How to tell if I have Wiseco piston
Attachments
20201225_155221.jpg
20201225_155221.jpg (3.23 MiB) Viewed 2072 times
20201225_153925.jpg
20201225_153925.jpg (3.31 MiB) Viewed 2072 times
Last edited by billie_morini on 01:27 am Dec 26 2020, edited 1 time in total.
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Re: Piston Identification with Inspection Camera

Post by KDXGarage »

viewtopic.php?t=22514

I promise to read your whole post soon, instead of just searching. :mrgreen:
Thank you for participating on kdxrider.net. :bravo:
To post pictures from a device: viewtopic.php?f=88&t=24128
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Re: Piston Identification with Inspection Camera

Post by KDXGarage »

Man. That's pretty cool. Thanks for sharing. Yes, it is OEM. It may not be the original, but it is indeed OEM (stock).

I am going to be bold (joke) and assume it has been in there a long time.
Thank you for participating on kdxrider.net. :bravo:
To post pictures from a device: viewtopic.php?f=88&t=24128
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Re: Piston Identification with Inspection Camera

Post by billie_morini »

KDXGarage, you are welcome. Gonna post some photos of piston in a few minutes now that I have the piston in-hand.
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Re: Piston Identification with Inspection Camera

Post by billie_morini »

For the benefit of those that want to know what the OEM (stock) piston looks like, here's a series of "good" photos. These photos show the top, side view with casting "waffle" pattern displayed, wrist pin bosses (big, round shoulders, whereas forged pistons require less material and are squared / squarish), and underside view with casting "waffle" pattern displayed (this is the underside of the top).

If this were a Wiseco piston, then you'd see numbers across the top.

It's possible to see the "SK" star and numeral 2 in the underside photos, which are key indicators for OEM piston.
Attachments
OEM_Top.jpg
OEM_Top.jpg (799.07 KiB) Viewed 2054 times
OEM_Side.jpg
OEM_Side.jpg (729.73 KiB) Viewed 2054 times
OEM_Inside_wrist_pin_bosses.jpg
OEM_Inside_wrist_pin_bosses.jpg (1.33 MiB) Viewed 2054 times
OEM_Inside_waffle.jpg
OEM_Inside_waffle.jpg (1.71 MiB) Viewed 2054 times
Last edited by billie_morini on 05:08 am Dec 27 2020, edited 1 time in total.
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Re: Piston Identification with Inspection Camera

Post by KDXGarage »

Again, thank you. That is very helpful to me and other lime green fanatics.
Thank you for participating on kdxrider.net. :bravo:
To post pictures from a device: viewtopic.php?f=88&t=24128
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Re: Piston Identification with Inspection Camera

Post by SS109 »

Hmm, I didn't know it was legal to own a destructive device without a Class III permit. I might have to report you to the BATFE! :boogie:

On a serious not, awesome pics and thank you for sharing them! :supz:
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