Before you look at these pictures, first let me explain how aggressive the KX port layout is, especially on the intake side.
The KX250 cylinder likes to leave vertical scratches on the intake side of the piston. This has been happening since I have been riding KX's (98-03). This is not dirt related trust me on this or jetting.The KX cylinder has a pretty huge intake window. I believe that when you are hammering, the up stroke of the piston presses into the intake opening of the cylinder, leaving the part of the piston where the ring end gaps ride pressing against the cylinder. Look at the pistons very closely. I never had a piston failure using any oil, but I was not happy with the look of the piston among other things until I used the 927 and KLOTZ. The other leading oil you see in the picture shows what I am talking about, I do not want to single out one oil, so I will not mention the brand, but I did use the ratio they recommended and I will tell you I was not confident in it. To be fair and honest, I am using avgas with the KLOTZ, the other leading oil I was using pump fuel, but I was using pump fuel with the 927 and was very happy with the results. The KLOTZ was run 40:1. On a side note the 04 KX's tin plate and streak their pistons to retain more oil HA!! The KLOTZ piston on the intake side is smooth as a baby's ......, no scratches. I pulled the pipe after a few hours on the new top end and I had very slight blowby on the exhaust side. After several more hours the blowby did not increase, so I believe that the blowby was only caused by the normal break-in period. I believe the flashpoint of the r-50 is 400 I like a high flashpoint ,but for running avgas(lead) and the high flashpoint the crown of the piston looks great.The black line you see on the bottom center skirt front and rear is magic marker I use to measure.
Keith 455.
"LET'S JUST RIDE"
PICTURES
[ January 14, 2004, 02:53 AM: Message edited by: KX 455 ]
The KX250 cylinder likes to leave vertical scratches on the intake side of the piston. This has been happening since I have been riding KX's (98-03). This is not dirt related trust me on this or jetting.The KX cylinder has a pretty huge intake window. I believe that when you are hammering, the up stroke of the piston presses into the intake opening of the cylinder, leaving the part of the piston where the ring end gaps ride pressing against the cylinder. Look at the pistons very closely. I never had a piston failure using any oil, but I was not happy with the look of the piston among other things until I used the 927 and KLOTZ. The other leading oil you see in the picture shows what I am talking about, I do not want to single out one oil, so I will not mention the brand, but I did use the ratio they recommended and I will tell you I was not confident in it. To be fair and honest, I am using avgas with the KLOTZ, the other leading oil I was using pump fuel, but I was using pump fuel with the 927 and was very happy with the results. The KLOTZ was run 40:1. On a side note the 04 KX's tin plate and streak their pistons to retain more oil HA!! The KLOTZ piston on the intake side is smooth as a baby's ......, no scratches. I pulled the pipe after a few hours on the new top end and I had very slight blowby on the exhaust side. After several more hours the blowby did not increase, so I believe that the blowby was only caused by the normal break-in period. I believe the flashpoint of the r-50 is 400 I like a high flashpoint ,but for running avgas(lead) and the high flashpoint the crown of the piston looks great.The black line you see on the bottom center skirt front and rear is magic marker I use to measure.
Keith 455.
"LET'S JUST RIDE"
PICTURES
[ January 14, 2004, 02:53 AM: Message edited by: KX 455 ]