81 KDX 175 top end issue

[walter]

Bought a NOS piston kit with new upper needle bearing and it does not fit the con-rod. I looked up parts number and confirmed it was correctly so, I thought somewhere along the road someone might have accidentally put the wrong bearing in the kit so, I bought a separate OEM part of the correct number and still doesn't fit. OD is slightly too big to slide into conrod, piston pin fits correctly as does everything else.

Anyone else run into this issue before? looking for someone with experience on this motor for other options.

[urgreathero]

sounds to me like mabie someone did a conrod swap. usually when conrods start to go bad, which is rare in itself they wear bigger not smaller. It could be some type of aftermarket conrod.

[C George]

Measure the pin and conn. rod dimensions with a GOOD digital vernier and call Action Bearing in Mass.

Obviously one exists as the old one came from somewhere. It's out there.

[walter]

Thanks for the help, I'm measure and let you know what I find out.

[walter]

turns out........there were 2 part numbers, the 1007 was too big and the 1004 fit perfect, finally got to hear it run today.

[walter]

If anyone needs the 1007 version, let me know I have 2 of them NOS Kawa parts

[KDXGarage]

It is good that you got it going.

Does the stock piston have an arrow pointing toward the rear of the engine?

Thank you.

[walter]

OEM piston that came out had arrow pointing forward, opposite side with small circle port milled into piston skirt on intake side.

The Wiseco piston look to be set up same way.

[KDXGarage]

I read from Eric Gorr that some version of the KDX175 had a piston with the arrow pointing backward.

Thank you for the hands on info.

[walter]

Curiousity will force me to research further as I'm inclined to believe what Eric Gorr publishes to the masses.

I sent my KX500 motor to him awhile back for the special treatment.......unbelieveable armwrenching, scare the bejesus outta of all your friends performance.