will a 250 kx motor fit in kdx 250 frame?

stu182

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#1
I know the numbers on my case say kx 250. But does anyone know if a reg kx 90-93 motor will fit in a 90-94 kdx 250>?
 

dirt bike dave

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#2
Stu, you should call Jeff Fredette - he would probably know for sure.

I believe some year KX250's will drop in, perhaps as early as an '88. Did you figure out what happened to your motor? Air leak, stuck throttle cable or something else before the meltdown? If it got super hot the spark plug would get heated enough to keep it running without any spark. Just my $0.02.
 

stu182

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#3
Dave, Still not sure. I'll prolly tear the top down tommorow. Something is bad wrong . To much grumbling to be ok. Drained the oil and there wasnt any metal or anything. I was going to put it in paper this week. But now gonna have to fix the hoe. Was thinking maybe if i could put a 92-3 KX250 or newer motor in it i may keep it. Still isnt gonna help the ride any.
 
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#4
Yes, it will fit. The '91-'94 KDX 250 D engine is basically an '89 KX 250 engine, with the same external dimensions, the only significant differences being a wide ratio tranny, heavy flywheel with lighting coil, smaller carb, and much milder porting. Many of the parts I buy for mine are KX parts. I was going to buy a KX cylinder for it, but the cost is just too high.
 
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#5
If the 89KX250 motor fits, will the lighting and heavier fly wheel slot in as well?
Basically, can we convert a KX250 into a KDX250 with lights as l want to keep the registration on the bike?

J
 
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#6
All you would have to do for that is buy a lighting coil and flywheel, or use the flywheel, stator, and cover from the KDX. That would be a better route than putting a KX engine in a KDX frame, as the KDX frame is made from cheaper (read: heavier) steel, and the suspension components, especially the forks, are cheaper and less effective.

With all this part swapping going on, what are the chances any of you will end up with a spare cylinder? I would be interested in buying it if so, I refuse to pay the $500+ that a new one costs.
 
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#7
I picked up a OEM KDX250 barrel for $150 Aust!!!

LOL, l'll just about crate the whole bike to you at the moment, found that the kickstarter decided not to engage. Pull her apart and all the splines and gears look fine, suspect the spring.
Is this a common trait on KDX250/200/220's?

J
 
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#8
The dealer here wants $530 US for a new KDX 250 cylinder, or $645 for a '89-'92 KX 250 cylinder. Even if you did want to send me one of those $150 Aust cylinders, it would probably cost me $500 US to have it shipped here.:scream: Thanks for the thought, though.;)

The kickstart problem you describe is not one I have had, so I don't know how common it is.
 
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#9
Check with Eric Gorr. I have a 96 kx 125 that the cylinder had a horrible leak at the flange from the cylinder. I looked every where for a cylinder for this bike. I couldnt find one for less than $409. I wrote Eric asking him if he knew where I could get one for less money.(since he deals with all kinds of cylinders everyday) He said he had a cylinder that was over bored to a 144cc and that he would throw in the piston rings and gaskets, also port it anyway I wanted for 375.00. Over all that was the best deal. give him a try might be able to help.
 
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#10
kdx/kx

spankys right find a kx and transfer ur ignition n wiring n lights minor brackets need fab like brake switch if u have brakelights and batterie in airbox