Piston Identification with Inspection Camera
Posted: 08:01 pm Dec 25 2020
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
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
