Buying a kdx that needs top end rebuilt.

1989KDXRIDE · Post by **1989KDXRIDE** » 08:36 am Feb 06 2013

this will be my first kdx buy. Going to pick it up tomorrow for $200. The guy selling says needs top end rebuilt and he is just to lazy to do it. What are some things that I should look at to make sure the bike is in good condition when I get there. Also is their any helpful posts or videos to help through the rebuild process? Thanks for your help.

Post by **scheckaet** » 10:31 am Feb 06 2013

check my sig

Post by **Julien D** » 11:28 am Feb 06 2013

The best resource you will find for general maintenance, including top end rebuild, is the service manual. Either factory, or cyclepedia. As for general condition, Wheel bearings, linkage and swingarm bearings, condition of chain and sprockets, etc. A look at the air filter will tell you a lot about how the bike was cared for if you're able to pull the seat. The info posted in Scheckaet's signature is great resource as well! Keep in mind, "top end rebuild" could end up meaning top and bottom rebuild and re-plate, which can run you up around $600 total. If all it needs is a piston and rings, you're in luck. For $200, I kind of doubt that is the case, but sometimes people get lucky!

1989KDXRIDE · Post by **1989KDXRIDE** » 11:51 am Feb 06 2013

Thanks for the great tips. Is there a way to check to see if the bottom end needs rebuilt and if it needs to be replated while I'm there? Or does it need to be taken apart to truly know? Thanks.

rbates9 · Post by **rbates9** » 04:40 pm Feb 06 2013

You could check the flywheel side cover for any oil in there as a sign of bad crank seals. And if he says it needs a top end and will start and stay running it might not be that bad. If what he really means is it stoped running and can't start it anymore then you should plan on a replate, top end and be ready to rebuild the bottom end. Also you can get a good idea of what the cylinder looks like thru the exhaust port if you pull the pipe. If the engine needs a replate, crank rebuild, piston and rings and so on it can quickly creep well past the $600 mark. You should look the bike over very close as to what it will need other then the engine work and see if the rest of the bike will be rideable once the engine is running again.

If the rest of the bike is in need of some love and the engine won't start and kicks too easy then you may want to keep looking. Keep in mind what the bike would be worth running and try to figure out if you can get it there for less then that.

Good luck with the search.

diymirage · Post by **diymirage** » 06:09 pm Feb 06 2013

one thing to look for is play on the connecting rod
(i realize you cant do this untill you get the bike home and the cylinder tore off but you sounded convinced you'r buying it allready)

so, with the cylinder off you can check to see if there is any play on the connecting rod
it is OK of it slides left to right but if there is vertical slop (up and down) your in trouble

to give you an idea what you might be looking at, here is the build of my project bike

i paid 400 for the bike and total investment right now is just shy off 1100
thats with a overbore, replate and over wiseco top end kit

http://kdxrider.net/forums/viewtopic.php?f=77&t=12547

1989KDXRIDE · Post by **1989KDXRIDE** » 06:29 pm Feb 06 2013

Im really hoping its nothing too drastic. The bike looks to be in great condition from the pictures. He has added lots of parts so I hope he took care of the engine too. I'll be sure to put a post up when I go check out (and hopefull pick up) the bike. Thanks for all the help. This forum is great.

rbates9 · Post by **rbates9** » 06:57 pm Feb 06 2013

I assume it is an 89 by your user name so just remember, 89 and new should be liquid cooled.

Just something to keep in mind.

1989KDXRIDE · Post by **1989KDXRIDE** » 08:41 pm Feb 07 2013

Alright got the bike today, super pumped. Bike looks great and everything seemed to check out. Got it for $120 its a 94 KDX200. 2 things before taking the bike apart and starting the top end rebuild. First the brake seems to be locked up. second there are 3 hoses running from the carb to the bottom of the bike (that just end) and one is leaking gas (black one in picture). Would love to know how to stop this. I will include a link with the pictures. Thanks guys.

http://s1279.beta.photobucket.com/user/ ... 0kdx%20200

diymirage · Post by **diymirage** » 08:49 pm Feb 07 2013

the good news is all those hoses belong there and they are overflow hoses
if your float is stuck (or badly adjusted) fuel will fill up the float bowl and then flow into the cylinder and kill the bike
to prevent his there are these overflow hoses
(though it looks like one of them was replaced with an odd hose)

long story short, your carb just needs to get clean and/or adjusted

really not a bad bike for the price
looks like a very good rebuild candidate

1989KDXRIDE · Post by **1989KDXRIDE** » 09:19 pm Feb 07 2013

Alright thats a relief. Any idea on the brake pad?

rbates9 · Post by **rbates9** » 09:21 pm Feb 07 2013

Looks like you got an awsome deal! I would start at the car wash.

rbates9 · Post by **rbates9** » 09:46 pm Feb 07 2013

1989KDXRIDE wrote: Any idea on the brake pad?

Start with removing the caliper and seeing if the piston is stuck or just the slide pins.

Post by **bufftester** » 11:05 pm Feb 07 2013

Like rbates said, judicious use of penetrating oil and heat should help loosen it. Regardless of what you find in the motor, for $120 you'd make money just parting it out. Looks like the typical 'left in the rain in the back yard' bike, just needs a lot of time and elbow grease to bring it back from the dead. Good luck

1989KDXRIDE · Post by **1989KDXRIDE** » 03:28 pm Feb 09 2013

Alright starting the teardown today. It says i need to drain the coolanat before doing the top end rebuild but i don't know where the drain plug is. Anyone got an answer for this? Much apprectiated.

Post by **bufftester** » 03:42 pm Feb 09 2013

It's a small (10mm I think) bolt on the bottom of the case directly below the water pump. Also don't forget to drain the overflow reservoir that is underneath the left side cover.

1989KDXRIDE · Post by **1989KDXRIDE** » 03:45 pm Feb 09 2013

Ok thanks, i found the one under the water pump, i'm just not seeing the one underneath the cover. Can you show me if i take a picture of the area?

Post by **bufftester** » 03:54 pm Feb 09 2013

Under the left side cover by the rear wheel

1989KDXRIDE · Post by **1989KDXRIDE** » 06:35 pm Feb 10 2013

Alright top end is completely off. Found the problem to the bike. Looks like the piston got extremely rubbed up against the inside of the cylinder. I took some pictures. I don't think the gaskets need replaced however. Can you guys give me a direction on how to get these things fixed and about how much its gonna cost? I know i need a new piston, i don't know what to do about the cylinder though. Thanks.http://s1279.beta.photobucket.com/user/ ... 0kdx%20200

diymirage · Post by **diymirage** » 07:29 pm Feb 10 2013

you need a replate at least, maybe a rebore

i had the same issue with my project KDX (a 96) i send it out to langcourt for an overbore and a replate
while they had my cylinder i had them match it to a wiseco piston and toss in a top end kit while they were at it

the whole deal cost me just over 400 dollars
the bore was only 30 dollars of that
i cant quite temember how the rest split up but i wouldnt suggest reusing the top end gaskets
in the grand sceme of things thats not really a big expense and i wouldnt spare it

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