Author Topic: kx250 time for rebuild?  (Read 2441 times)

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Offline thegreengoblin

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kx250 time for rebuild?
« on: July 12, 2015, 02:18:52 PM »
hey all, just was poking around the interweb and found this forum!
I've had my 2003 kx250 for a bit over 3 years, awesome machine, love it to bits. I ride mostly woods and technical trails and have set it up for that, but it's mostly stock. The last ride I noticed it started slobbering more out the exhaust than it used to. I just got back from a 5 day trip to the dunes and I have a funny feeling this will be the last season the engine. I used to have a bit of oil on the outlet of the silencer and a drop or two might drip out of the slip joint onto the swing arm. That would be after one ride. now after one ride it's a stream all the way down the silencer and lots of drips on the swing arm. I also fouled a plug that last ride, which I've never done in 3 years of riding. I would say i've ridden well over a dozen times each season. So if nothing goes wrong, come December I will pull the pipe off and have a look at the cylinder walls and piston skirt. What do you guys think, is it signs of rebuild time? Am I being too paranoid? This is my first bike so I've never rebuild a 2 stroke

Offline sandblaster

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Re: kx250 time for rebuild?
« Reply #1 on: July 12, 2015, 03:20:28 PM »
Hi thegreengoblin and welcome to the forum...
Sadly I'd say you are due for a rebuild.
How extensive will depend on what you find when you get the top end off.
Do yourself a huge favor and get a Service manual for the bike before you start and give it a good washing before you take it apart...
Post pics of what you find.
The four stroke engine: That's one stroke for producing power and three for wearing the engine out.

Offline umberto

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Re: kx250 time for rebuild?
« Reply #2 on: July 12, 2015, 03:28:59 PM »
I would definetly get the manual and read all the way through the section.  In addition, it helps to watch a video that shows the process before you attempt it.  This is a really good video from Rocky Mountain ATVMC on rebuilding a top end.  Good luck and post lots of pictures!

https://www.youtube.com/watch?v=-FFIWtqU5Zc
Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525/2017 KX250F - Goliath
17 KX250F/04 KX250
04 KX 250 - Lunchbox's Bike
05 KX 125/144

Offline thegreengoblin

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Re: kx250 time for rebuild?
« Reply #3 on: July 12, 2015, 06:26:17 PM »
thanks guys for the advice! yup, gonna need a manual this is true.
pretty sure I need my cylinder re-coated, last time I had the pipe off to re-seal the O-rings I found a groove I could catch a screwdriver on. running horizontal around the cylinder, very strange, rebuilt lots of engines, never seen that before. only thing I think that could cause that is it sitting for a long time.
I've been poking around the internet and been very tempted by doing a 300 big bore. Talked to kustom kraft about it, not a whole lot more money. anybody have any thoughts on doing a big bore? I'm mainly looking for more torque in the bottom and mid.