1993 KDX 250 Questions...

[Rangerman]

Greetings,
I just recently purchased a 1993 KDX 250.



I am evaluating its overall condition and trying to determine what needs to be repaired and or replaced.
I verified that it did indeed have sufficient spark so I moved on to rebuilding and thoroughly cleaning the Keihin PWK 38 carby.









Everything went well concerning that so I then cleaned out the tank and the petcock which was an unexpected mess.
The results of ethanol and long term storage revealed themselves.



Afterwards I flushed the radiator and refilled with fresh fluid and bled.
I also drained the old gear oil and filled with fresh oil.
It fired right up and idled just fine.
I took it for a spin and shifted through all the gears without any problems.
Acceleration impressive.
The compression seems to be a bit low based on how the kicker felt through its rotation.
I have not done a compression test on it yet but intend to.
I was curious to know if anyone can confirm the possibility of interchangeable parts between the KDX and the KX of similar years?
I am in need of a silencer for it and have located a '96 KX250 OEM in decent shape and at a decent cost.



It would be good to know if any KX parts are compatible and if so what they may be?
Any information would be appreciated.


Rangerman

[KDXGarage]

Welcome to kdxrider.net. It is nice to see a member with a KDX250.

Good job on the work so far. The petcock looks nasty.

Some 1989 or 1990 KX parts might work, but mostly it is KDX250 only. I am not sure on a silencer working or not.

Does it currently have NO silencer at all??

[Rangerman]

Welcome to kdxrider.net. It is nice to see a member with a KDX250.

Good job on the work so far. The petcock looks nasty.

Some 1989 or 1990 KX parts might work, but mostly it is KDX250 only. I am not sure on a silencer working or not.

Does it currently have NO silencer at all??

Thank you for your quick response and the compliment.
Yes, the petcock took more time to clean than the carby did, the residue was almost like a hard clay in consistency.
I used acetone to clean with, it was the only thing that would cut through it.
Carb cleaner did not even faze it!
No it does not have a silencer on it at present, it did not come with one when I purchased it.
I was considering out of curiosity using my FMF that I have on my '92 KTM 300 EXC just to see if it would fit?
If so then I would most likely not have any difficulty locating one off of e-bay knowing for certain.
I was hoping to only have to do that as a last resort though.
I would rather not have to buy one new if at all possible as I am still in the process of determining if this old (almost) vintage machine is worth my time and effort?
So far, so good though as I am impressed with it overall.
It most likely will need a top end as the compression is considerably less than that compared to my '92 EXC or '91 DXC.
Unless KDX's differ in that respect? It starts easily and maintains consistent idle along with running through the gears quite impressively.
I just recently got it running the other day after the Keihin carb clean and rebuild.
I would like to consider this as a prospect for some friendly amateur Enduro's here locally if all goes well with putting it back into shape.
I am just taking it a step at a time though starting with the most basic issues.
Thanks for your help.


Rangerman

[KDXGarage]

What country are you in? AUS? I see you calling it a carby.

If it cranks and drives around, then it is definitely far ahead of many rebuilds.

Not sure of what is available in any country outside USA for parts. Put something on there to keep from going deaf.

[Rangerman]

What country are you in? AUS? I see you calling it a carby.

If it cranks and drives around, then it is definitely far ahead of many rebuilds.

Not sure of what is available in any country outside USA for parts. Put something on there to keep from going deaf.

My Aussie "KTM" friends (in the land down under) terminology (on another forum) must be wearing off on me... carby, mate, etc...
I am in fact living in the good ol' USA, I was born here.
Compression will most definitely have to be addressed, I will verify when I test it.
I do not plan on riding without a silencer I just wanted to make sure the gearing functioned along with satisfying my curiosity if the machine would at least move forward, which it did.
I believe I will try the FMF, I have a hunch that it will work.
Pipe diameter appears equivalent, I may have to be creative with locating mounting points.


Rangerman

[KDXGarage]

Look on eBay to see what you can find. I know at one point, Answer made two versions of a spark arrestor besides the Pro Circuit silencer and FMF spark arrestor.

[Rangerman]

Just for the record a 1996 KX250 stock silencer will in fact fit a 1993 KDX250.
I installed it without any modification using the existing mounting hole.



I did a compression test on my KDX (warmed up and throttle open) and it read a whopping 90psi!
I knew that the compression was low as indicated by the kickstarter being so easy to push down effortlessly with my hand.
I just wanted to verify with a compression tester.
I will be putting a new top end on for sure and will inspect the cylinder when it is disassembled.

The loaner compression tester from Autozone.


Adapter and plug...



Rangerman

[KDXGarage]

WOW. Interesting on the silencer fitting well. That is good.

Do check out the internals. DO NOT buy a piston before measuring what is inside and checking the cylinder and such.

[Rangerman]

It will be thoroughly inspected as I always do.
It may just need a new set of rings as I do not know how many hours are on the last rebuild.
I do not know the history on this and so am at a loss to determine its overall use and maintenance/repairs?
Still it is a KDX and that is good enough reason for me to invest my time and effort it bringing it back up to standards.
It has been interesting for me to compare side by side it's nemesis the 1992 KTM 300EXC and get to observe their similarities and differences.


Rangerman

[Rangerman]

The bottom bracket lined up perfectly and the top bracket need to be moved to the outside of the rear fender.



It plugged into the header pipe perfect.




Rangerman

[Rangerman]

1993 Kawasaki KDX 250







Rangerman

[Rangerman]

Rangerman

[Rangerman]

Alright then, time to get down to business.
First another picture of the '96 KX250 silencer final mount.
One mounting point will provide adequate stability.
The other mounting bracket rests very snug against the subframe.
Good enough.







Now to start the top end inspection.
What I have yet to determine is exactly what the minimal is that has to be done.
Just rings?
Piston and rings?
Cylinder work (bore), piston and rings?
Disassembly begins.
Removed plastics.
Removed gas tank.
Removed pipe and silencer.
Drained radiator fluid and removed hoses.
Removed carby.




Removed intake manifold.



Removed reed cage.



Which appear to be in excellent condition.



Intake port.



Exhaust port.



To be continued...


Rangerman

[KDXGarage]

I would suggest that you remove the neglected power valve system and clean it well.

Keep up the good work.

[SS109]

It would only take a few minutes to make a bracket to secure the silencer with both mounts. Just my 2 cents.

Disassemble the whole top end, clean everything really well, and scrub the cyclinder with a Scotchbrite pad, then take pics and post them up. Personally, I would replace the piston, rings, top end bearing, and all gaskets and seals of the top end so you know what condition everything is in.

[Rangerman]

I would suggest that you remove the neglected power valve system and clean it well.

Keep up the good work.

Thanks.
Any tips (tricks of the trade) on removing the power valve?
It looks to be a different animal compared to my '92 KTM 300EXC & '91 KTM 300DXC
KIPS?
This looks to be an informative video about it.

Are the KX models set up with this type of power valve too?


Rangerman

[Rangerman]

It would only take a few minutes to make a bracket to secure the silencer with both mounts. Just my 2 cents.

Disassemble the whole top end, clean everything really well, and scrub the cyclinder with a Scotchbrite pad, then take pics and post them up. Personally, I would replace the piston, rings, top end bearing, and all gaskets and seals of the top end so you know what condition everything is in.

Yes, your two cents make perfect sense.
I have a bracket in mind that I could mod to fit, so why not go the extra mile right?
Where do you get the Scotchbrite pads, I have looked at various stores and not been able to locate them?
I will continue to post my progress (albeit slow) as I go so any help or advice from those that have "been there done that" would be greatly appreciated.
So far I must say I am impressed with this KDX.
Coming from a KTM background although not a purist, it seems to be on par with it's European rival... so far.
Your input is appreciated.


Rangerman

[KDXGarage]

grocery store for green Scotchbrite pads

The bracket would be a nice addition. Look at the 1989 - 1994 KDX200 version for an example.

[Rangerman]

Excellent information.
I just recently recieved some relevant info from a fellow KTM enthusiast and friend who appears to have as much knowledge about KDX's as he does KTM's and wanted to pass it along.
It pertains to my most recent endeavor of inspecting my '93's top end and may be useful for others in the future who will be doing the same.
Here it is.

HEY!! @Rangerman . sorry for the delay. almost forgot to get back to you on your KDX question. i was unable to link your kdx link as my phone was acting up. been away from home and my computer. just a few quick ideas here. your 250 is based on the older kx motor and around 93 was the change year for the old type drum valve. the later kx used a blade type around that year. the kdx 250 was an awesome bike and like the suzuki rmx was a detuned motocrosser. im pretty sure your kdx was based on the older kips drum type exhaust valve. i dont have too many manuals around anymore, but i would only suggest you should not have any troubles with that type cylinder. the actuator rod stays on the governor for cylinder removal and exhaust valve is removed carefully out the access cover, be sure to decarbon valve drum with wd40 and scotch brite pad so as not to scratch valve bore. i take tons of pictures for reassembly and i use an electric engraver to mark and index all parts before disassembly. aerosol gasket remover spray is magic for removing carbon from ports and cylinder and exhaust valve parts. you can also use the wifes spray oven cleaner as a substitute. but wear gloves and dont breathe that stuff. be sure to flush that stuff from parts and spray them with wd40 until it drips off. will research more as time allows. regards

And also,

okay buddy. i had a peek at those pictures you posted. you can probably expect your piston to be a bit collapsed from the look i got through the exhaust port. no worries, as long as the cylinder coating is decent you are fine. exhaust valve is a carbon covered mess. i cannot identify valve type but i was pretty certain those 250s used the old school drum type valves with 2 outer sub exhaust valves. i dont remember the stiffener ribs in the exhaust port shown, but it could be newer upgrade im not familiar with. good idea as a lot of those old 2smokers used to gall piston and sieze there on the older ones. the good cylinder shops used to relieve that part of cylinder with die grinder and drill lube holes in pistons to prevent that problem. looks like kawi fixed that one for you. i looked at pictures of the complete bike and my recollection of your motor is identical to the older 88-90s kx 250. i think i may have pictures of my 89kx.....im always digging through bins of pictures.

Good stuff from a good source, just thought that I would pass it along.
To be continued...


Rangerman

[Rangerman]

Back on task...
Slow but sure...



Removing the 14mm cylinder head to frame bolt.



Loosening the 12mm cylinder head nut in a crisscross pattern a little bit at a time.



Removing the nut with an 12mm open end wrench.



Keeping track of cylinder head nut location.



To be continued...


Rangerman