cylinder scoring

[tominator]

I just replaced my piston and I noticed some scoring on the cylinder wall. The lines were very shallow and mostly located around the intake port. I was really surprised by this because my bike has less than 50 hrs on it ('04 KDX220). Most of the hours have been spent following my kids around. I clean and oil the filter after every ride.

I found no evidence of any burrs or any other source for the scoring.

Is this normal???

How bad does it get before I need to re-plate it?

 

[nectar]

I wouldn't worry about it.

 

[Kwakasaki]

Why did you decide to replace the piston so soon? I have an 04 220 also, just curious.

 

[adam728]

If you can run your finger nail acrossed the marks and snag them I'd say it's time for a bore / replate.

Kwakasaki
The stock 220 piston is crap and prone to breaking off the skirt, which can cause mucho $$$ to repair. Many people choose to replace it before the headache. I also ride a 220, which I bought new this summer. I got a new Wiseco to pop in it, figured I'd do it before something bad happened. Too late. The locating pin on the piston backed out and put a huge groove in the cylinder. Luckly the dealer covered it all on warrenty, but I'm still putting in a Wiseco rather than the stocker. If you hop up your bike at all you will be much more likely to break the piston as well.

 

[tominator]

I heard about the stock piston being weak. I didn't want to risk it.

The marks are mostly below the x-fer ports, but one goes all the way to the top.
I can barely feel one score with my nail it is not very deep.
I can't feel the others too shallow.
The piston has no matching marks.
The ring pins are not lined up with the marks.

It almost looks like it came this way.
Can you hone a plated bore without screwing it up?

 

[andrew]

yes, it can be honed. if it's only the one groove that can be felt, get a very fine piece of emery paper and give it a light rub to take the edge off.

cheers,
andrew

 

[Kwakasaki]

Adam 728, Thank you. I just read some of the same statements on other threads about that. Guess I will get busy yanking a head. $150 is cheap to remove a grenade.

 

[adam728]

I got my Wiseco piston, rings, wristpin, and circlips for $94 shipped from www.rockymountainatv.com . Not sure on gasket cost, the dealer gave me those with the new cylinder and stuff.

 

[Colorado Mike]

I got the whole top end gasket kit for $28.99 from the same place, I heard that you can take the cylinder and head off as a unit, thus saving on the need for the head gasket. If that pans out I'll have an extra for future use.

Mike.

 

[motorider200]

I heard that you can take the cylinder and head off as a unit, thus saving on the need for the head gasket.
Mike.

The only down side I can think of to doing that is you can't get to the sub-exhast valves for cleaning. I'd say go ahead and take the head off an put a new gasket on, they do go bad sometimes.

 

[Woodsquest]

Remember; if the scoring is below the rings when the piston is at bottom dead center, then it won't affect compression. Check the ports for sharp edges. Kawasaki KDX's are known for flaking off the plating at this point. If that happens and you are lucky, the scoring is below the ring line. Otherwise, it will depend on how many and how deep. It really won't "hurt" anything but maybe a bit of performance, so I wouldn't sweat it if I were you.