Maintenance & Technical > KDX (KX step child)

My 91 kdx 200 rebuild

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shizcol:
hey guys kinda new here and have some help needed..

  so i picked up a 91 kdx in great condition cosmeticaly and was told it needed a top end.. when i started taking it apart, i noticed that the piston had broke and parts of it ended up in the case.. so now the crank wont turn all the way around unless the motor is on its side.. i looked inside and it looks aweful.. so many little broken pieces of the piston and it just made my day worst.. this bike is in such goos shape tho, it came with a complete fmf exhaust, boyesen reeds, renthal bars, a nice skid plate, excell wheels, the plastics are in awesome shape and i just dont know what to do.. i cant see myself parting this bike out.. it needs a motor.. sadly, but i paid 200 bucks for the bike.. what should i do?


i also picked up a 88 kx 250 for free.. it runs but needs tlc.. i want to do a resto on it, but it needs more then the kdx does.. needs plastics, and exhaust.. the old one is beat up.. but it runs.. ..


     just didnt know if i should fix the 88 kx 250 or try and find a motor for the kdx or should i send the motor in and have it done? how much am i lookin at to have the kdx running again? i really need opinions on this.. please.. i wanna ride.. thanks for all ur time..

Goat:
That is a nice looking KDX. Personally I would rebuild the engine and get it going. They are great bikes and parts are pretty easy to find.

I would pull the engine out of the frame and flip it over to get the piston pieces out of the cases. Don't forget to drain the oil first. How does the rod look/feel on the crank? As long as you can get all the pieces out of there and the crank and rod spec out it should be fine to throw a new piston in. How is the plating on the cylinder?

Unless you find one hell of a deal you're looking at spending between $500 and $800 on a complete engine. For that you can completely rebuild the one you have yourself and basically have a brand new bike. You may have to do that even if you get a new used engine so you'd be spending twice as much money.

If you do decide to scrap the kdx engine let me know as I would like an extra one to do some mods to for the quad I built.

Now for the 250. If you decide to resto it it's going to take some time to find all the new parts. If you are looking at just fixing it up check with Mike (sandblaster) he owns OEM-Cycle. He parts motorcycles out and has a bunch of lists of parts that interchange between years. He has his own section here: http://www.kxriders.com/forums/index.php/board,43.0.html

Hope this helps. Any other questions just ask. No question is a stupid question either.
Cheers
Goat

shizcol:
Hey goat thanks for the reply. I decided to take the engine to a shop in the morning. I took the bottom end out of the bike and took all the oil out and i flipped it upside down and tried to
Get all the pieces out but there is too
Many small pieces. I can get the crank to turn nice if its on its side but if i put it up it wont turn all the wAy. Im gonna take it to the shop in the am and have them split the cases and clean all that crap out. Hopefully it didnt damage anything. And if so im gonna have them fix whatever is wrong. Then il do the top end. Thats all thats wrong with this bike. It is in great shape. Just missing the left side cover and thats it. I dont want to sell this bike or part it out i want to build the engine up and hope for the best.

 As for the 250 i changed my mind as it needed way more stuff then my kdx. It was a basket case. Needs new plastics and exhaust and the top end needed to be redone and it needs a clutch and the kickstarter is messed up so i said hell il put the money in my kdx. I apreciate the help man. Keep in touch i might need ur help along the way lol.

Goat:
Glad to hear you're fixing the ol 200 up. They are quick, reliable and fun bikes. I've had a few of the early 90's kdx's and love them. Not sure how much over stock power you want to go but I believe one of the guys in the services section may be able to mill the head to give a better compression ratio for more power. IIRC the kdx stock puts out around 30hp. If you'd like to learn more on upgrades and slight changes you can make to make the bike handle better and make the best power check out these sites: http://www.craig.copperleife.com/bikes/kdx/index.htm http://www.frpoffroad.com/aboutus.htm

I'll help out any way I can.

shizcol:
Ur the man. Thanks for the tips and links. I will check them out. I will try to keep updates going here as well

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