Plated cylinder inspection

[sbleakle]

I have an '89 KX250 that I got a few years ago but have not ridden it much. I recently picked up another one that was dissasembled about 10 years ago due to a broken 4th gear on the output shaft. I plan to rebuild the motor. All the parts have been sitting in a garage so they are in good shape but need cleaned up a bit. My question is this: In inspecting the plated bore, what am I looking for? The texture of it is a little rough due to a very light dusting of rust, mainly from just sitting around. Should I get one of the Wiseco brushes and clean it up or what's the best thing to do? In my initial measurements (with inside mic), it appears to be within specs. I just don't want to get a ton of money in this thing as it will just be a playbike.

Thanks,
Steve
Tulsa

 

[BlazinBoy]

You should be able to use emery cloth to remove the rust. As long as there are no deep scars or pits on the cylinder walls you will be good to go.

 

[Mr. Clean]

A quick check with a feeler gauge will give you a fairly accurate reading. Here's how. Install the piston without the rings in the cylinder. Slip a feeler gauge between the skirt and the cylinder. Four thousanths is technically worn out but will work. Two and a half to three would be better. Measure in the middle of the stroke because the greatest wear is there.Make sure everything is perfectly clean and oiled because a little grit will give you a false reading. Mr. clean