Max bore on a 2003 CR125 Heard many different things

[Norcalmatt]

Hello guys. I received a cr 125 in a trade in my benefit even if it is not as upgraded as he said he was. The bike rips i will give you that and has a wicked power band because of the sticker that gives it 30 more hp on the side of it. Seriously though. He said the engine has been bored to the max and there is no way to tell from the outside from what i can tell. The bike runs great and is faster no joke than my crf 250x that was completely done up. (besides bottom end). I know is has the unbreakable levers but that is it pretty much. I have not been into two stokes too much, alls i know is that is has the expansion and pipe which is nice. It has a huge jet which i know it is not stock, but i wish i could tell what bore it is ex. Can anyone tell me what the max bore the bike could be and is there a way to tell if it is indeed upgraded as much as he said. I do know it has showa shocks for sure as well. Thank you all, its good to be back, but im trying to get back on a thumper. Thanks guys!

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[YZ250F06]

Take off the cylinder, measure the circumference of the combustion chamber, and compare it to what the stock value is.

Generally those bikes need to be stroked after 144cc (remember displacement = bore x stroke)

[JJRace]

max is a 134cc

56mm bore from the stock 54