Kx250f question

I crashed the bike last weekend.dislocated my shoulder and tore a tendon after i got loaded in the cart my brother and riding buddies loaded my bike and everything so i didn't see it for 5 days well the only thing broke was a bent bar clamp got them ordered well my brother hopped on it and states it was Gonna take it for a spin when it started i knew he left the tail plug in i ran and ripped it out... Now im paranoid the valves sound like they ticket louder... The plug was in maybe 5 seconds can that ruin the valves with back pressure?

Absolutely not. You did no damage.

Thanks dragon confirmed with a dealer earlier turns out that's how they check for exhaust leaks?

I've done this multiple times by accident after washing my bike, like dragon said you did no harm.

Valves probably sound loader because you normally on the bike with a helmet on when its running. 

possible Muffler Bearing damage!

possible Muffler Bearing damage!


I had not thought of that.  If that's the case, the muffler bearing would need to be replaced before it strips out the power band.  I don't think it's an emergency because the idle valve compensates for the compression differentiation.  There are a couple built in redundancies.  The other one is the hot-start re-set, which disengages the pilot thrust bearing if the muffler bearing doesn't return the right resistance to the ECU.  Besides, muffler bearings are a lot more stable now, and most people use the Sigma aftermarket setups that dealers started to install in '06-'08.  Even if they don't, the OEM Ti ones in '09 and later models last a lot longer than the magnesium ones used to, as you know.  In my case, I bypassed the circuit all together (the silver wire mod).  Saving $163 doesn't seem like it's worth it, but I refuse to buy ceramic.  As a result, I no longer get the coughing (barking) sound on decel and my low RPM power is better than ever.  Some flattening at the top, but that's to be expected.  I just threw a 49T rear sprocket on to compensate and switched to Rotella T.  Had to re-gap the plug to .06mm to prevent detonation, though.  Anyway, it is unlikely the OP could trash the muffler bearing with a brief run time like that.  He can check the power band on the next oil change.  Probably just a little discoloration from the blow-by, but nothing of consequence.

And, yes OP, Al and I were just kidding around (not at your expense, but ours!)  It was a good question and you have a good answer.

No worries just semi new to the 4 stroke valve system lol

No worries just semi new to the 4 stroke valve system lol


As long as you know I was just having fun with Al's response.  There are no bad questions, so if you have any doubt, ask.  Glad you took it the right way.  I hardly ever kid around, but he teed it up perfectly, and you were safe with the original answer.  I have a video of a "normal" sounding KXF I will attach for you in a minute.  Just have to find it.  If yours sounds a lot different, we can discuss.  

Here is what the bike sounds like from all sides.  Sound familiar?  th_VID_20130606_184847_zps829becc9.jpg

yea I was messin with ya. worst thing that can happen is a fouled plug.

Dragon, I got a nice remap for your 2011 if you can get ahold of a program connector set.

I did three with different power curves ,

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