Checking in on problems you guys are seeing with the 2024 Kx 250
Here is my problems
25 hrs crankshaft failed list big end on Rod
Put new crank in bike and new bearings.
30 hr later now dropped a valve, appears to be from broken intake valve spring dropped the valve broke the guide and bent two other valves. Or cam gear might of slipped causing piston to contact valve, breaking valve spring and broken guide.
Going through another full rebuild, going to put a proX rod on stock crank, thinking about kibblewhite valves and spring kit, probably put a new cam on intake or at least verify that the gear did not slip, will probs my tack cam gear.
Doing these things will this stupid bike be reliable.
Checking to see what the B riders are doing with these bikes for reliability. Bike is stock.
Yes - piston, valve, and crank failures are a known thing for the 23 and 24 KX 250.
I know a guy who’s 2024 KX 250 crank bearing seized on the first break in ride. They pulled the crank and the oil weep holes and grooves were not cut all the way.
He rides for the Kawi test team in Holland, so it wasn’t his own bike, but those motors seem to have a hard time holding up to high level riding in stock form, as other members of his test team had issues with valves and rod breakage.
Now, they tear down their 250 race motors and replace valves, connecting rod and piston before a single hour is put on the motorcycle.
They also use a Vortex instead of the stock ecu so the bike doesn’t run too lean.
One note- Our 2024 KX 450 crank bearing disintegrated at 9 hours and took the rest of the motor with it . Kawi said no to any warranty coverage. We rebuilt the motor ourselves with a piston and rod from a euro spec Kawi 450, , and 25 hours in no issues.
hopefully Kawi improves QC, but I wouldn’t bet on it based on history…
Did you use stock crank when you rebuilt? Also what valves & valve springs?
No wonder they are knocking $2K off...
Yeah back in January when the bike blew up, no one was making any aftermarket motor parts for the bike- we even had to get OEM parts carried over from Holland because Kawi had none in stock here. The bike was too new at that point, so all we had to choose from was OEM.
Our motor guy Derrick did go through and polish the ports and clean the oil passages in the head that were cast poorly- the OEM casting was quite sloppy and crude- but then again we did have one of the first bikes out. Bike was raced at Fox round one and Hangtown round two and ran flawlessly.
When the bike gets rebuilt we will go to an aftermarket connecting rod, valves, and springs. Apparently there have been reports of those breaking also on the 450.
Since the guy Robert who races the bike when he is in California is a tester for Kawi, he kind of knows all the engine problems before they get wide spread.
Kawi stock clutch baskets, that is another lovely topic…💩
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Several B (national B level, not local B level) riders that I know locally are riding 450s for all practice sessions and only using the 250s for races. They apparently are great bikes, but have extremely short longevity. This is all second hand, as my son (not national
races KTM 250Fs, which have their own set of issues.
Yup- KTM and Yam 250fs seem to be the most durable stock motors , but the crazy, very creative search for more HP in 250’s turns these little bikes into volatile ticking time bombs- high performance, high risk,
Kawi stock 250 motors don’t respond very well to a skilled racer very long, at least that is what the people who race these bikes tell me….
Also, some of these OEM stock gearboxes are not made to withstand the extra load a highly modded motor puts on them…
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