Author Topic: Rebuilding my 1987 KX 250  (Read 31998 times)

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Offline dinkyguitar

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Rebuilding my 1987 KX 250
« on: April 15, 2014, 02:31:03 PM »
Well, got her on Saturday and I started taking her apart.

I ordered a service manually and hopefully I can get all the parts I need to finish. The motor has compression and does turn over freely. My cousin said it was running strong before he had issues getting it in 2rd, them later problems getting it in neutral. I kicked it over with the plug out and it does have spark so technically it should start when I'm done.

I'm going to make a list of all the parts that I need before I start buying anything just to make sure I can get them.

So far, I'll need a water pump cover since a piece of the lower front of the cover where the mounting screw goes in is missing. Looks like something hit it. I might try using aluminoid welding sticks and try to build up that area so the screw can sit nice and flat to seal everything.



The stator looks like it has some type of oxidation that should clean off.



Supposedly the carb was rebuild. It looks clean for sitting in shed for 8 years.





And this is what happens when a bike sits for so long...a family of mice decide to move in....found 4 dead inside. It was not pretty.



Another pic:



I was able to see inside the cylinder looking through the exhaust port and it looks good so far. I can see little vertical wear lines on the piston. The top of the piston looks normal too.

I was surprised that I saw the cross hatching on the cylinder. Would this mean it had a top end job done? Or should you see cross hatching normally?

Anyway, it might be awhile before it's all put together and running. With 3 kids, finding time might be a challenge.

dinky,

Offline motopunk

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Re: Rebuilding my 1987 KX 250
« Reply #1 on: April 15, 2014, 05:10:58 PM »
the cross hatching says, that the cylinder and piston could not have many hours on it since last rebuild...   the bike has a good restoration base...   your only real problem is the gear change... try to find a good used ´87 transmission with all 3 forks , replace the old snaprings and the engine is ready...  :wink:
big 2 stroke bikes are weapons for real men, who don´t fear death or devil. ;O)
´83 kx250, ´87 kx250 (with 360 big bore), 87 kx500, ´93 kx500 sfc

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Offline sandblaster

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Re: Rebuilding my 1987 KX 250
« Reply #2 on: April 15, 2014, 05:20:23 PM »
I'd like to see the cylinder with the head off...
Cross hatching is a good sign but it depends on what it all looks like.
The four stroke engine: That's one stroke for producing power and three for wearing the engine out.

Offline dinkyguitar

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Re: Rebuilding my 1987 KX 250
« Reply #3 on: April 15, 2014, 11:47:20 PM »
My thoughts exactly on those changes in the trans motopunk.

And once I pull the motor out I'll definitely see what the rest of the cylinder looks like  sandblaster.

One question:
If the cylinder turns out to be ok, I'll still change the piston & rings. But how to you prep the cylinder?

dinky?

Offline Foxx4Beaver

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Re: Rebuilding my 1987 KX 250
« Reply #4 on: April 16, 2014, 06:33:50 AM »
So far, I'll need a water pump cover since a piece of the lower front of the cover where the mounting screw goes in is missing. Looks like something hit it. I might try using aluminoid welding sticks and try to build up that area so the screw can sit nice and flat to seal everything.

here's a water pump cover if you're interested....

http://www.ebay.com/itm/1987-Kawasaki-KX250-water-pump-impeller-cover-87-KX-250-/200917426312?pt=Motorcycles_Parts_Accessories&hash=item2ec79ca088&vxp=mtr
Excuse me, ma'am...but you've got extremely nice legs!!!...what time do they open???                                                                                                               https://www.youtube.com/watch?v=n8tCgN3aryQ

Offline dinkyguitar

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Re: Rebuilding my 1987 KX 250
« Reply #5 on: April 16, 2014, 06:39:40 AM »
Good find Foxx4Beaver!

I know there're out there...just a matter of time before I buy one.

My flywheel puller is shipped and so is my service manual.

Today I'm hoping to test my stator and coil just to make sure they are in order.

dinky,

Offline Foxx4Beaver

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Re: Rebuilding my 1987 KX 250
« Reply #6 on: April 16, 2014, 06:48:29 AM »
Excuse me, ma'am...but you've got extremely nice legs!!!...what time do they open???                                                                                                               https://www.youtube.com/watch?v=n8tCgN3aryQ

Offline Oblivious Maximus

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Re: Rebuilding my 1987 KX 250
« Reply #7 on: April 16, 2014, 12:50:45 PM »
That's a Goldmine of parts there Foxx.  I've had my 87 for a year and a half and have never seen that many NOS parts in search.

The intake boot is a real rare one.

Dinky.... Your gonna love it.
Where the Hell is "Easy Street" ?

Offline Foxx4Beaver

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Re: Rebuilding my 1987 KX 250
« Reply #8 on: April 16, 2014, 12:57:50 PM »
That's a Goldmine of parts there Foxx.  I've had my 87 for a year and a half and have never seen that many NOS parts in search.

The intake boot is a real rare one.

Dinky.... Your gonna love it.

this guy's got some goodies too, I've bought from him before...search his store...he's got TONS of nos stuff for various bikes.

http://stores.ebay.com/Motorcycle-NOS-Parts/_i.html?_nkw=+87+kawasaki+kx250&submit=Search&_sid=156402798
Excuse me, ma'am...but you've got extremely nice legs!!!...what time do they open???                                                                                                               https://www.youtube.com/watch?v=n8tCgN3aryQ

Offline dinkyguitar

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Re: Rebuilding my 1987 KX 250
« Reply #9 on: April 16, 2014, 02:16:46 PM »

The intake boot is a real rare one.


I have to admit...I was eye'ing that too...

Well, cleaned the airbox assemble and the carb, and took 1 radiator off. I think I might baking soda blast it before final assemble.



No more mice in the air box....glad I clean that out.



Not sure if I've have time tomorrow though :( . I mean I do have a wife and 3 kids that need attention every now and then :).

dinky,
« Last Edit: April 16, 2014, 02:18:26 PM by dinkyguitar »

Offline sandblaster

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Re: Rebuilding my 1987 KX 250
« Reply #10 on: April 16, 2014, 03:27:11 PM »
One question:
If the cylinder turns out to be ok, I'll still change the piston & rings. But how to you prep the cylinder?
dinky?

For me it depends on if it is Nikasil plated or sleeved.
If it is plated, I mic it to be sure it is in spec, then I use WD-40 and some Scotch Brite and run it diagonally till it's good and clean.
If it's sleeved I mic it to be sure it's in spec, then I run a 340 grit ball hone, spraying it liberally with auto trans fluid so that I make a nice diagonal cross hatch, then clean and re-inspect for problems as a ball hone will often make slight scoring show up.
In both cases I disassemble and clean my exhaust valves and replace any seals or o-rings.
It  is also a good idea to lap your cylinder, cases, and head to insure a perfect fit upon re-assembly.
I would also take a close look at your cylinder stud condition.
Then, when I am really happy with the results... I would  thoroughly clean the whole assembly in hot water with Dawn soap..
That's the basics of what I do...

PS. This site is way better then that other lame site you posted on  :-D
The four stroke engine: That's one stroke for producing power and three for wearing the engine out.

Offline dinkyguitar

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Re: Rebuilding my 1987 KX 250
« Reply #11 on: April 17, 2014, 12:12:34 AM »
Thanks Sandblaster,

How do you lap the cylinder and other parts?

dinky,

Offline sandblaster

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Re: Rebuilding my 1987 KX 250
« Reply #12 on: April 17, 2014, 02:59:17 AM »
For now, let's just say that this stuff is awesome...

The four stroke engine: That's one stroke for producing power and three for wearing the engine out.

Offline Foxx4Beaver

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Re: Rebuilding my 1987 KX 250
« Reply #13 on: April 17, 2014, 05:52:52 AM »
For now, let's just say that this stuff is awesome...

I'll 2nd that!...

Excuse me, ma'am...but you've got extremely nice legs!!!...what time do they open???                                                                                                               https://www.youtube.com/watch?v=n8tCgN3aryQ

Offline dinkyguitar

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Re: Rebuilding my 1987 KX 250
« Reply #14 on: April 22, 2014, 12:46:13 PM »
Progress has been slow...but here's what she looks like now.







The magneto was pretty good shape...It had some surface rust on the out side and inside. I submerged it in evapo-rust and all the rust is gone.

I did see a thin layer of plastic on the magnet which is flaking off but I think it should be good.

Today I took the clutch cover off and was hoping for the worst but I got a surprise...It looks like a new clutch???? There's no ridges on the barrel at all. And the clutch plates aren't fused together. I thought there was something wrong with the clutch because when I pulled the clutch in, the bike was still in gear. Now I'm not sure if it's just the trans since my other problem was that I couldn't get it in neutral and the prior owner skipped 2nd when used to ride it years ago.



dinky,