Kx250 1986 correct piston size for my engine, what to order??

[tracks]

Hi all,

I believe I need to get a new piston kit or maybe just rings??

I have some pictures below to try and show the condition of my cylinder and piston - how do you know when you just need to replace the rings or the piston as well? I did a compression test and it was low at something around 25/30PSI (I'm not sure how accurate my tester is but thats what I got..)

The measurements I have managed to get are as follows:

CYLINDER: 69.72 - 70.02 mm
PISTON: 69.85 - 69.88 mm

(I did clean the piston)







Thanks for your help!!

[Foxx4Beaver]

I'm sure others will give their thoughts and opinions...but if it were me, I would re-plate the cylinder, new piston/rings/wrist pin/wrist pin bearing/circlips....throw those crusty old cylinder studs out and put in some crispy new ones...(but after you have lapped the cylinder and head to be sure they're both flat!), and a complete Cometic top end gasket kit.
Then you know everything is new and should last you a while providing you're good at keeping on top of your general maintenance.

[tracks]

Thanks for your response, yes I agree thats what it does really need but I just want to get the bike running (understand it won't be as good as it could be) - it's just not really worth spending the money on. I'm prepared to put another £100ish into getting a new piston kit but after that I might as well sell it and buy something in a better state..

[bens87braap]

I bet if u spent  300ish u wouldnt want to sell it   just my 20 cents worth Id rather fix it then u no what u got and u will respect it more