Nikasil coating

[KX125pinball]

I own a 1999 CR250, i just replaced the piston and was wondering something. The piston that i took out was worn on the intake side and the CNC machining marks were smoothed out. I didn't take off the head to see if the bore was worn. I was told if i want to see if it's worn, take off the head and feel for a ridge where the piston comes to TDC. Keeping in mind the condition of the piston and the fact that there is honing (crosshatch) marks still present in all places, does this sound like the bore is still in good condition? I looked at it and i can see no bare aluminium exposed! Also the bike is a Japanese import and the bike doesn't seem to be as ridden and much as the bikes i see locally.

 

[Spammer125]

The bore probably still good. My rule of thumb is to see if the crosshatch is still present. Wether this is correct or not I'm not sure.

 

[DEANSFASTWAY]

The bore will also wear out at the bottom of the stroke near the intake . The piston skirts will wear at the intake side also. Best to go to a bike or machine shop & have the parts checked with a michrometer for wear . Also check the Honda piston skirts for cracks on the intake side . Loss of plating will be a good sign that it is worn but not as conclusive .

 

[KX125pinball]

Thanks guys, i will be replacing the piston every 40-50 hours of riding because i've heard that the skirts on the pistons can snap off! Don't want that to happen