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High Speed Crankcase leak

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hi . new member and have been looking into this issue on the board. nothing yet. new to 4 strokes

ok here it goes, just got a used 07 kx450f all stock. i have put about 6 hours on it and havnt had any problems. i went riding this week and after banging thru the gears on a fire road i stoped and noticed oil all over my frame, rim, tire, sprocket, swingarm, and under the case. ( maybe a half cup? i cant b sure)-.. it came from the crankcase breather hose on the left. anyway i let it cool down. no leaks. so it started rite back up and we continued riding another 2hrs. i didnt do anymore high speed or full out runs . and no problems. i checked the filler window and it was still full. ran fine and no more leaks. ??????????? any ideas on Y ?? thanks guys (no leaks or problems b4 or after that situation) 👍 washed it all down and no signs of leaks or drips.

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It really sounds like the bike was overfilled. You will be ok. DO NOT use the sight glass. It is not accurate at all. This has been explained to death here.

It will blow out what it does not need, and equalize, which it did. I would not worry about it, just watch it, to make sure a seal is not blowing by at higher engine speed.

BUT may be safer to drain and put in the right amount. Then I would test it again, to be sure. I would.

Amounts from your year manual.

0.96 L (1.01 US qt.) (when filter is not removed)

0.98 L (1.03 US qt.) (when filter is remove)

1.2 L (1.3 US qt.) (when engine is completely dry)

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thats kinda what i was thinkn. but why only at high speed ? i thought it does that at all the time when its overfilled.

thinkin about it seemed a LITTLE down on power at that time to. when these engines get hot do people notice hp or turque (spelling) loss, is that normal to you guys.

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Rings could be going bad. If the rings start to go compression can get past them at higher rpm's and pressurize the crankcase. In which case the pressure has to go somewhere and that somewhere alot of times is out the breather hose, taking a little bit of oil with it.

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i guess the rings make sense. maybe i should redo the top end then. is that a pretty serious problem should i do it asap or can i continue riding for some hours ? -dumb question- . got trips comin up and no money. haha

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Id test it yourself or have it tested. Its super easy to do yourself and you can buy the tool for like 15$ at pep boys or any auto store. You can ride it but it will eventually blow your main seal and you'll start leaking oil from behind your sprocket. Thats IF it is the rings. you may have just over filled the oil but id check compression just to be safe.

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