2001 kx 125 cylinder piston questions

Jonathan_Williams
Edited Date/Time 1/7/2020 11:15am
Bought a 2001 kx 125 for my son for Christmas he got maybe 3 hours on it and lost compression couldn’t even get 40psi it was low when I got it I believe it’s been a while since I kicked a 125 over so I just thought it was normal bc it fired up first kick every time but then it started to not want to kick we had to push start it before it went completely out I pulled cylinder and piston I will send pictures wondering if I can throw a new piston in and roll with it cylinder has been sleeved has one faint mark on cylinder but you can’t feel it and it has a wiesco position with 54mm std bore .. any help would be great trying to get this sad kid back up and going as fast as possible.. thank you

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SmokinJoe439 1/3/2020 11:41am
1/3/2020 11:41am
Well the cylinder has a steel liner pressed in it which means the pervious owner must have messed it up and took the cheap route to fix it.

Most likely you will have to get it bored out to the next bigger size piston. Steel liners is oldschool tech if the piston is left in to long. The bore will wear and require a rebore to the next size to get things back into proper tolerances.
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Jonathan_Williams 1/3/2020 1:19pm
1/3/2020 1:19pm
Ok thanks a lot so would I be better to get next piston size and get it machined or try to get a new cylinder and go back factory bc I kinda jumped the gun and ordered a new piston kit 🤦🏻‍♂️
Jonathan_Williams 1/3/2020 1:22pm
1/3/2020 1:22pm
I was just trying to get him up and running fast as possible think if use a ball hone and clean it up it might last a little while it still has cross hatching in most of the cylinder and no groves
SLOWTIME
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SLOWTIME 1/3/2020 4:42pm
1/3/2020 4:42pm
You do not need to get it bored. Sleeved cylinders can be plated to retain the stock bore.

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Jonathan_Williams 1/7/2020 11:14am
1/7/2020 11:14am
Update new piston honed cylinder and is running great for now hopefully he can get some time on it so I can save up enough money to buy a new factor cylinder and piston fingers crossed 🤞🏼

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