F-12 Valve hit Piston - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts
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Old 06-05-2011, 09:16 PM   #1 (permalink)
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Default F-12 Valve hit Piston

My 'new to me' 2004 F-12 suddenly came to a halt with the motor froze up, got the head off and found that one of the exhaust valve retainers came off or broke, allowing the valve to hit the piston. Needless to say this trashed the head and the piston. If I am lucky the cylinder won't need to be bored, there are some light scratches.

But I just bought this PWC 2 months ago and limited my search to non-turbo 4-cycle Honda and Yamaha with the belief I would be getting a strong durable motor that would last for years. And to have it fail due to something that is not related to maintenance but only something can be attributed to either a bad design or bad quality is really disappointing considering it is a Honda.

This motor had never been opened, believe me the corrosion on some of these bolts leads me to believe Honda does not use high quality SS when they should. The hours were just over 250.

My internet searches have not turned up others with the same problem, but I can't beleive I am the only one, although I was one of the first to have a Ford Expedition to burn up, leading to the recall....

Has anyone else heard of this problem with the Aquatrax motors?

PS: If you are working on your cylinder heads, you might want to inspect or replace your valve retaining clips.
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Old 06-06-2011, 06:09 AM   #2 (permalink)
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The resident Honda geru Is who you need to rap with. If he doesn't see your post send him a PM, his forum name is ,"JRINJAX" he is from Jacksonville and swears Hondas are the best skis on the planet. Heh, heh, I don't think so. Maybe the best discontinued ones. lol. Thats why I ride nothing but Seadoo 4 strokes, can't beat those Austrian motors.
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Old 06-07-2011, 09:19 AM   #3 (permalink)
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Yes Honda has had a problem with valves floating at high RPM and being struck by the piston. From looking at your pictures I see a PWC that has been destroyed by a lack of maintenance by the prior owner. You might have had internal corrosion/lack of oil changes that caused the valve to stick or maybe it is just Honda's weak springs. I had an engine fail from a valve strike on my '02 F12X. You definitely need a whole new engine and motor mounts due to the corrosion shown. Parts are available on Ebay motors.
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Old 06-07-2011, 11:48 AM   #4 (permalink)
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So you are suggesting that the valve was floating open too long and hit the piston, not the spring retaining clip that failed? I had not thought of that option.

In these Honda motors can the piston hit the valve if the timing is off or would the valve have to float open past the distance the cam normally opens it?

In other words would the piston/valve collision occur because the valve floated beyond it's normal space or because it stayed open too long and the piston can occupy the same space as the valve?
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Old 06-07-2011, 06:18 PM   #5 (permalink)
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The valve floats open too long and the upcoming piston top knocks the valve up, releasing the keeper. Then the valve drops and the bigger collisons snap the stem.
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