2000 kx 250 motor in 1987 Frame? Can it be done?

[dinkyguitar]

Hi All,

Just one of my options right now since parts are hard to find.

I'm adding up the cost to fix the motor and it's coming close to the price of a good used 2000 kx motor I found.

So how much moding do I need to do to get it to fit?

dinky,

[motopunk]

Hi All,

Just one of my options right now since parts are hard to find.

I'm adding up the cost to fix the motor and it's coming close to the price of a good used 2000 kx motor I found.

So how much moding do I need to do to get it to fit?

dinky,

thats definetely a job for the advanced kx-wrencher!...

the 2000 engine fits to the 87 lower motormounts, but its still a lot of modifying the 87 use 8mm motorbolts and 15mm swingarm-bolt . the 2000 engine has 10mm boltholes and 17mm swingarm-bolt...
last year i had a 96 engine in my 87 frame...  you need a completed modifyed pipe , bolt-on-headstay or a 2003/04 cylinderhead, handmade-bushings everywhere for the motormounts and swingarm-bolt...handmade brackets for the headstay... 
here you can take a look at it: http://der-motopunk.de.tl/projekt-evo_racer-kx250E1-.htm

if i where you, i would rebuild the 87 engine or try to get an good used 88-91 engine. that would make some things easier for the engine swap...
second option: you can try to fit the 2000 crank and cylinder to the 87 motor-bottom, but also not as easy as it sounds in first...   

[Foxx4Beaver]

Hi All,
Just one of my options right now since parts are hard to find.
I'm adding up the cost to fix the motor and it's coming close to the price of a good used 2000 kx motor I found.
So how much moding do I need to do to get it to fit?

dinky,

I'm not trying to discourage your ideas in any way....but, I think it would make more sense to sell off all your 87 parts, whether as a whole or parted out...then take the money you where gonna use to rebuild the 87 engine, or buy the 2000 engine, and buy a complete running newer bike.
You said it yourself..."parts are hard to find"...not impossible, but it could take a long time before you find everything you need.
Between selling off the 87 and all the parts, and taking the money you where going to use to rebuild it, or get another motor, you should have a decent amount of cash to find a newer bike where parts are more readily available.
Just my thoughts, and the way I'd go.

[dinkyguitar]

Thanks guys....

I'm still searching to see if I can get the right parts for this bike....

dinky,

[motopunk]

Thanks guys....

I'm still searching to see if I can get the right parts for this bike....

dinky,

which parts do you need for your bike??   

[dinkyguitar]

I'm actually starting to find more and more parts for it.

Partzilla.com had most, if not all of the bearings and seals for the crankcase and the ones I couldn't find on that site I found cross references for.

But the transmission gears and stuff was one of the things I couldn't find new. I actually bought a whole used trans for that as well as the shift forks...which BTW I did find 1 shift work that was brand new OEM.

dinky,

[motopunk]

I'm actually starting to find more and more parts for it.

Partzilla.com had most, if not all of the bearings and seals for the crankcase and the ones I couldn't find on that site I found cross references for.

But the transmission gears and stuff was one of the things I couldn't find new. I actually bought a whole used trans for that as well as the shift forks...which BTW I did find 1 shift work that was brand new OEM.

dinky,

crank- seals or engine seal-kits , gasket-kits for the older kx-bikes are easy to find by cometic, athena, mitaka , prox, allballs and so on...
if you have the right measurements, you could find the bearings also on free market , look for koyo or skf bearings thats the right quality... 
that works also for the bearings and seals in the wheels... 

[treedodgingfool]

http://www.bikeboneyard.com/87%20kx-250.html. Ive bought a few things off of this guy in the past.

[dinkyguitar]

Hey motopunk.....how did you make the swingarm bolt fit the 87 frame?



dinky,

[motopunk]

Hey motopunk.....how did you make the swingarm bolt fit the 87 frame?



dinky,

 

i used the 87 swingarm bolt..

for the 15mm-swing arm bolt and the 8mm-lower engine-bolts, i took a 0,8mm steel-plate and made bushings to reduce the 10mm bolt-holes and 17mm swingarm-mount of the newer engine to the right size... like i said, its tricky, but possible to make...