Wildguzzi.com
General Category => General Discussion => Topic started by: steven c on July 07, 2020, 08:01:30 PM
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Riding down to the shore last Thursday on my new to me 09 KLX250s just died while doing around
65 mph which should not have been a problem. I pulled the head today and found an intake valve had come apart and wedge itself into the valve seat. The right doesn’t look that great. First motor in 40 bikes that I killed. What would cause this. Defective valve?
(https://i.ibb.co/zfnbYjf/DF268-B52-3-C5-F-4-CDC-A872-F85-DB0935-DD7.jpg) (https://ibb.co/zfnbYjf)
(https://i.ibb.co/RzvJt5w/204-CD628-ED13-46-D7-98-EF-F8978-CB00-A25.jpg) (https://ibb.co/RzvJt5w)
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It is eleven years old . How many miles ?
Dusty
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that is a untypical , usually the hotter exhaust valve fails
the only cause i can think of is a bent valve due to the valve hitting the piston at some point.
most likely over revving.
once it is bent it will flex at every rev, until it eventually fails due to metal fatigue
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Bike has only 5K on it. I only put on a couple hundred since
I bought it last fall. It seem to be running fine up till it didn’t.
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The head of the valve separated from the Stem. Valve check wasn’t do till 12K.
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Do you have a photo of the piston?
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Do you have a photo of the piston?
2nd photo.
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I'm not up on all the new higher performance light weight 4 stroke dirt bikes and if yours is a similar design to the Hondas, but I'll relate the following.
A few years ago, one of my teenage neighbors, had a very low strung, mild tuned Yamaha 200? dirt bike that ran well no problems;
He replaced it with a higher strung Honda 250 CFRX?, it was much higher performance and almost immediately he started to have trouble starting it.
He spoke to me about it and I researched it at the time and learned that, poor starting indicated a need for valve adjustment.
He had a repair shop adjust the valves and it started and ran excellent,,, for a couple of weeks,,, then back to poor starting.
When I researched it on line, people in the know indicated that when the valves needed constant adjustment, it was an indication that the valves were stretching and getting ready to self destruct.
Options were to replace the stretching valves or flog the bike,,, the kid made a wise choice and got rid of the high strung bike, replacing it with a milder tuned trail bike.
I'd be checking out some of the forums dedicated to your bike, but I think most of the new high strung 4 strokes can be hard on valves and I think one of the recommended fixes is replacement with Kibblewhite? sp?
Good luck with it
Kelly
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Well the KLX isn't high strung they are well known as a bullet proof motor that you can't kill. Basically the same motor as the 300 just a bigger bore. People put a 351 kit on these and flog them with no issues. Seems the lifters are pitted.
(https://i.ibb.co/XCD4Mfc/DSC7489.jpg) (https://ibb.co/XCD4Mfc)
(https://i.ibb.co/ZT291xS/DSC7490.jpg) (https://ibb.co/ZT291xS)
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Piston photo, I think it can be saved.
(https://i.ibb.co/BBQZjhw/DSC7491.jpg) (https://ibb.co/BBQZjhw)