Kawasaki KLX250s to 300 kit
 

Hello from Sydney i recently got a 2022 KLX250s that the previous owner ran way too rich on fuel and has worn the piston rings a puff of blue smoke on initial throttle opening then goes away. I have leaned it off bike runs fine but in the future probably this winter will take down engine. With the cost of genuine parts being so high i was considering a 300 kit but all info i can find for the 300 kits stops at 2014 models does anyone know if 2014 will fit later models or has fitted one. All help appreciated if i need to post in another area of this forum let me know. Thanks.

Key in a search for 300 big bore. A good number of riders here and probably in the ADVrider forum have used the AHL kits along with others. The AHL 299 kit will fit, since I'm pretty sure all the 250s and 300s swapped cylinders over the years, so 2014 shouldn't matter. The AHL is almost a bolt on and is low priced. The only modification needed is the tensioner spring retainer bolt on the cylinder will need to have the threaded portion cut about 4mm shorter. The AHL cylinder isn't tapped deep enough, the bolt is easier to shorten. I put one of the kits on my bike. Under $200 usd on Amazon last time I looked. I got it for $152 about five years ago. Just make sure it says for the KLX250, there is a 292 kit that does not fit.

Ahl kit
 

Don't get too concerned with the way the head gasket isn't fitted exactly to the water ports, that bit of overlap causes turbulence in the coolant making it more efficient at drawing heat from the cylinder. If the fits were perfect it would promote laminar flow, which would result in the inner part of the flow wasn't drawing the heat due to not contacting the cylinder surfaces. Unlike the intake, the coolant flow is at a low enough speed the imperfections allow adequate flow while making the coolant turbulent.