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I had the opportunity to pick up a new bike for next season a little early. I was talking to a friend about how I was in the hunt for a new bike and he told me this guy had a 98 KX250 2Smoke for cheap because he was scared to do motor work. PERFECT winter project bike.

-Friday I picked up the bike and prodded the man for information (service life etc.)
-Saturday a buddy and I took our bikes (99yz400f and my newly acquired 98kx250) for a shake down run at Dorr Run trail head in Wayne National Forest.

This is the story of the days since.



After doing a quick bolt check, tire pressure and the usual stuff, we headed out from Columbus and picked up fresh gas, 4 fresh spark plugs and fresh 2smoke oil.

We arrived and unloaded and hopped on the trail system, realizing that the owner told me that the bike "leaked" oil, we brought a small bottle of trans fluid(80w gear oil) to 'top' off the bike if it needed it.

After the first couple minutes we realized that "leaked was an UNDERSTATEMENT"






By the end of the first 30 minutes of riding we realized that my bike was FOGGING the entire woods, but we drove a long way to ride so we just kept topping it off until we decided to call it quits and only had 1 spark plug left (of 5).

A bike this old usually has little O-rings and seals that let go, this one happened to have the crank seal between the gear side and hot side let go as well as some others. We knew of the potential problem and I was willing to do the work when I picked it up.

So here starts the tear down



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As Ugly as this tank is, it holds a TON of fuel for long trail days.
Unhooked the Carb boot, stinger junction and subframe.
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Removed the Gas tank and Radiators and Hoses.
Unhooked the Carb and harness.
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Upon Initial motor tear down we found some interesting things.
I don't have many pictures of them as they didn't come out well at such close views.

The case covers had miscellaneous hardware swapping (Think Phillips head screws instead of 8mm/10mm bolts), the clutch cover seal was ripped and RTV'd back together, and the worst of all, inside the clutch side, behind the crank shaft output spline, the "leaky" seal had been clear silicon bathtub caulked into place. The seal was leaking so badly that they cracked it open, saw that they needed to split the cases and glued it together and ran.


LEFT SIDE Shaft is Surrounded in CAULK!

Mechanically its fine, it just boggles my mind how people get that far and then quit instead of learning something and spending 100 bucks.

As the bike sits right now its waiting on a flywheel puller and parts to come in.

I ordered the full gasket set, I am going to order a top end kit (Rings Piston Wrist Pin bearings etc) and do it right from the bottom up.

So far I am at under 200$ in parts.



MORE PICS TO COME THIS WEEK.
 

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Looks like a funbuild-up! I'm doing the exact same thing on a 97 CR500 I pikced up a few weeks ago. Thankfully, I did not have to deal with bathroom sealants anywhere on the bike!

My eyes lit up when you mentioned riding at Dorr Run! I grew up riding in the WNF, and spent probably 10 years riding the main [and not-so well known] trails around there. Brought back a lot of good memories.
 

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Discussion Starter #4
sweet! I love build threads.

can we ask how much you payed for it?
You very well can ask, So far here is the breakdown:
Bike 1000$
Fluids 35$
Complete gasket and Seal set 80$
Spark Plugs 8$
Top End Kit (Wiseco) 205$
Miscellaneous Hardware 15$
MSR 3 position clutch lever 50$

That's All I have spent so far... It will continue to grow through winter I'm sure.
 

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Discussion Starter #5
Update

Here is a progress update:

Today I had Iron Pony of Columbus remove my flywheel (off the books), I also ordered the Crank Seals(33$) and had my bore measured by GSpowersports next door to Iron Pony as the Pony did not have the bore indicator.

Here is where the fun began. GSpowersports measured the bore at 68.53mm.
Stock KX250 piston size is 66.4mm!
Piston that came out was a 68.5mm, which makes this a 265cc 2stroke!

To replace the piston (had a hairline crack forming) I need to order a 68.5mm piston. Tolerances are stated in Inches so here's the math:
BORE 68.53mm to inches is 2.698in.
Piston 68.5mm to inches is 2.6968in

Clearance cold will be 0.0012 inches. From what I have read this is within tolerance, even on the tight side a little.

So I am ordering a 68.5mm piston kit from DennisKirk.


Also I found that my KIPS power valve gears are very worn, so I should be ordering those today as well.

I'll keep you guys posted
 

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ya very cool, I love picking up bikes that run but need boatloads of TLC

my most recent is a cr500 that ran (when push started) but made a whopping 65psi of cylinder pressure!

...actually I think im going to start a build thread
 

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Discussion Starter #9
Quick Update:

Piston, Rings, Pin, clips, and bearing are on order and should arrive this week. I have had the luck to place all my orders through the worlds largest motorcycle superstore. Check out IronPony if you have never heard of them. They have a retail location here in Columbus check this place out:

IRON PONY PICTURES <<---CLICK ME


This used to be a large big box store (think walmart/kmart/target etc). They even have bays for the old tire center being used as a SHOP.

I love the fact that they carry all major brands and have things like water pump impellers IN STOCK!

Sometime this week I will update with pics of the new parts and the install.
 

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That's cool. I'm with you, I understand people that are scared to tear into something, I get that. But the people that tear it all apart, only to half ass it then throw it back together, that I don't get either. I had a '93 KX 250 with a little work done that I loved more than any dirt bike I ever owned.
 

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sweet.....i am rebuilding a 2002 cr250 AF that i picked up for $350 with a title, but a seized motor:headshake i have a "new project" thread inthe chatsection......I split the cases and am waiting for parts right now. Luckily, i did not find any home depot sealant in mine! You might want to pick up a Tusk crank case splitter to split the cases.
 

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oh man im in the middle of rebuilding a 1997 kx 250 that i got for a whopping $100. frame has had some cracked welds repaired but not repainted. im doing it all shocks (all leaking) new rear rotor, powder coat frame. top and bottom end rebuild. im too lazy for any pictures other then cell phone pictures and i wont steal your thread. looking forward to see how yours turns out!
 
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