Cause of Broken Intake Valve | Honda GX390

4 Stroke Kart Engine Forum
1

What would cause the top of the intake valve to break off (valve lash?). Kart was idling on the stand when this happened?

Valve lightly struck piston. What parts of the engine do I need to check for damage or replacement.

Suggestion for best and cheapest place to buy parts to keep it a stock speedy kart?

Thx for any help.

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2

Hard to identify a cause. Does it spend a lot of time floating the valves during a lap? What kind of peak RPM are you seeing? Looks like it’s got a good amount of time on it.

Personally I’d inspect the cam to ensure it’s not damaged, same for pushrods. Then replace both valves and springs as a precaution.