So this last March I bought a brand new leftover 2015 kx 250f. I did all the proper break in, oil changed every ride, oil filter every other ride, air filter not necessarily always tempted with but it gets inspected before every ride. Anyways, 6 hours comes around and it develops a terrible knock like I've never heard before. Take it back to the dealership I got it from because I wanted nothing to do with fixing that out of my pocket. Turns out somebody at Kawasaki made a mistake when assembling it, they left some sort of steel fastener loose somewhere between the air boot and the cylinder, which made its way into the cylinder. So my piston rammed the piece of steel repeatedly into the cylinder head, destroyed the head (especially the cast aluminum pieces on the outside). Kawasaki determined it was their fault, replaced my head, valves, everything in the head basically, and my piston. Left kinda a sour taste in my mouth that this even happened in the first place to the only new bike I've ever bought, and the 2nd 4 stroke. Anyways, fast forward to 22 hours (mind you, it had a new head at 6.) and bike won't start. Turns out the valves are stuck shut, no clearance whatsoever even with a .0005 feeler gage. I do my best detective work to figure out why, air box itself is a little dirty, air filter is sub par, but I inspect air boot and see absolutely no trace of anything getting past the air filter, and no signs are leading to it being from dirty air. I have a temperature sensor on the engine and it never goes above the target range, never pisses coolant, never had a problem with it getting too hot. So anyways, I shimmed the valves, bike started fine and ran fine. Now here I am at 28.4 hours, bike won't start again. Ok pull the valve cover, check for clearance, none whatsoever. This is just in the intake valves, the exhaust valves have had no issues. But if I'm going to replace the valves, I may as well replace all of them. Now does anybody have good luck with any particular valve brand? I'm worried since stock valves are titanium, once whatever coating is on there gets worn off the valves life is essentially done. Should I go titanium? Stainless? Should I go oem or is somebody else making higher quality stuff? Has anybody ever had something like this happen to them before? The dealership offered me a discount on oem parts, anybody think this could be related to a lingering issue from what happened at 6 hours? Bike rarely sees the rev limiter, and gets absolutely babied.
