I have 74 hours on my 350 and am considering a new piston and checking the valves. Am I being paranoid on the piston? When is a good time to consider changing? It gets ridden reasonably hard in MX.
Are any kits worth considering other then the KTM. Their piston kit is not cheap ($524).
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I did my 23 at 100 hours. Valves were spot on, and piston skirt was getting shiny. I used all oem parts due to contingency money.
If you’re good with your oil changes and air filters, and the bike isn’t giving any signs of a worn out top end (ie blue smoke, hard to start etc) then 100 hours will be fine.
As for hardware, I’d just stick to OEM, especially if you plan to keep the bike, very very hard to beat OEM quality. You could go for cheaper parts if you’re selling soon but in never seems to last as long.
Have you tried shopping around for the OEM piston kit? Surprised to see its that much when here in Australia, it works out to be around 360 USD for a top end kit.
I did total rebuild on my '22 KTM 350SXF at 180 hours. It still looked great and the tolerances were well within spec. This bike was ridden hard two years of Loretta Lynns and local A/B MX, so she wasn't babied. Constant oil changes and air filter changes. I think KTM's are built really well too, so that helps. If you have the means and want to rebuild, for sure, can't hurt anything.
It depends on how you ride it. Some of the guys ride the bike like it's a 250 and scream the shit out of it. We've been going around 80 hours If it's ridden hard. The top end wear will most likely be fine but it's a good time to go through as much of the motor as possible. There was a 58 hour failure around my area on a 2024 but it wasn't the top end.
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I think most guys do their pistons way too early, notice every time people post about doing rebuilds or top ends at low intervals they say everything looked brand new, you are just wasting money and introducing more potential for failures.
This was from my 2021 350 with 200 hours, 120 of them were B level GNCC and hare scramble racing not exactly on the rev limiter but certainly not an easy life. I put 60 hours on the new top end, timing chain before I sold it.
Maybe I'll just check the valves and call it good!
I have 138 hours on my 23 now. I’ve checked the valves 3 times and only had to change a couple shims one time. Runs great. I’ve increased oil change frequency and will most likely do a new top end this winter. Did a leak down test last week and it’s only at 7%. Thought it’d be more with high hours.
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