86 Tecate w/ 94 KDX250/ 93 KX250 engine, build thread.

[elvetost]

Thought I'd throw this here, as I been playing with the kdx 250 motors for a while..
There is also another kdx250 engine that goes in the kdx250sr (91-94) or kdx250f (f1-f4). The sr is the street ready version of the kdx, mostly jdm but there's a few about europe etc as well..
This more uses an even wider gear ratio than the kdx250d which is the enduro version you guys got in the US.
It also comes with heavier duty coils (larger), a heavier flywheel, a smaller carb (pwk 34), different reed cage with oil feed (they interchange though), oil pump, and the best of all COUNTERWEIGHT!
Now it also comes with a different piston(same bore), where the piston pin is located 3-4mm lower and hence the rod is 3-4mm longer in there. Its also got a 19mm piston pin bearing (vs18mm). Same stroke as the kx/kdx250d.

For my trail bike I mixed and matched 3 motors and made me a kdx250f2 motor, with a kx250 rod, pro-x kx250 piston, kx250 1990 cylinder (sleeved), 38mm pwk and the rubber boots off the kdx250d, so it all fits stock. It runs a pro-circuit pipe with a kx250 oem silencer. So I have the ultra wide trans (seriously this thing can do 160+kph and its got an uber high first gear too!), heavy flywheel, counterweight and all the power I could wish for. This makes a very useable bike for the trails, it is very little tiring and pulls like a mule!
THIS THING RIPS!

Anyways, I could prolly help out with any kdx motor questions you got. Plenty of experience between me and my team green mates out here.

Hope this is of use to anyone!
Cheers!
Chris

[bkm]

Well I've decided to go ahead with this project. I located a nice 93 KX250 top end on ebay for cheap and decided to snatch it. I knew that late model top ends would bolt on to the KDX lower end, but what I didn't realize is that in 1992, Kawasaki lengthened the stroke and decreased the bore on the KX models and since the KDX engine is based off of the 88-90 KX engine, it still had the shorter stroke. Luckily the guy I got the 93 top end from also had the matching good crank to go along with it. This was all a blessing in disguise, because last night I got the KDX cases split in order to swap out the cranks and discovered the oem crank bearings were toast. This will be a kind of Frankenstein engine with a '94 KDX cases and transmission, and 93 KX250 crank, cylinder and piston. I'm curious to see how well the KDX ignition works with the more aggressive KX porting. I may have to swap out for a KX ignition later????

So I have everything disassembled now just waiting on parts. Once the engine is together I'll start working on the frame and powder coating everything to assemble the roller.

I'll try and get some pics of the engine and frame work soon.

[aldochina]

gonna be a cool piece BKM!! Nice to have a sweet project going to take a mental break from reality huh!! Will be checking back for updates bud!

[bkm]

Brother, you're not kidding.

These Kawasaki engines are pretty cool. It's amazing how simple they are and how much interchanges between different models. The only beef I have so far is that the cases have to be split in order do do crank seals. They press in from inside the case. Other than that, I was able to split this thing in about an hour and that was taking my time.

This one is also going to be a flat tracker/tt bike. After the engine is together all I really need to hunt down is a good rear shock.

[cr480r]

I'm curious to see how well the KDX ignition works with the more aggressive KX porting. I may have to swap out for a KX ignition later????.

I don't think the kdx ignition gives up anything in hp. But for flat track or any sustained rpm use, I would be leary of the flywheel hub cracking. It's bigger than a 500 and may not like excess rpm. I had a hub crack back when it was in the trike and getting dune ridden. Two used ones I bought were also cracked. May have been a fluke, I don't know because I put it in a dirtbike not long after that and mostly ride in the trees now. My motor would be a beast with a tiny kx flywheel...

[torker]

For the intake, you may be able to use a TECATE manifold to fix the angle of the carb (if that is in fact the problem). Good air boxes are hard to come by and spendy.
Jeswinehart, here on the boards, makes a great reproduction intake manifold for the TECATE, should you need one.

TORKER.

[cr480r]

The angle of the reed box on the cylinder is different after '88. A tecate (or early kx)intake will likely leave the carb bowl resting on the cases. A clamp on filter is the easiest solution, a tapered spacer could work although ghetto imo. Best option for a stock airbox is a build a custom aluminum intake with a rubber clamp like a rad valve.

Edit: sorry. I had it backwards the newer reed box is steeper, so the carb would rise not drop. With the old intake. The exhaust port that is flatter on the newer stuff, probably where I got confused. I had my kdx mocked up in a quad racer briefly before I put it in the bike. I remember I didn't like the angle the carb sat with tecate boot, but I suppose it would work.

[bkm]

I have not addressed the intake alignment since buying the 93 kx cylinder. Hopefully this project will pick up once the indoor race season is over. I really need to work on this thing.

[nd4speed]

Are you going to use an air box? or clamp on filter? Is it for flat track racing? Wouldnt the POD filter be shielded by the motor some if going in counter clockwise circles on the track? When I took mine out on the frozen snowy lakes , I made a cheesy cardboard shield for the POD filter cause ice would build up on it.

My thought is if you use the proper boot (or rad valve) for the year 1993 or later than the carb angle should be relatively level like normal.

I use a 1990's KX250/500 boyesen rad valve on my 1986 Tecate motors and it is fine with TM and PWK carbs. Picture of KX500 motor with KX500 boot.

Was really interested in this project because of the KDX250 motor and trans, but they are hard to find around here.

[bkm]

I have a rad valve and will most likely use a pod filter. I'd love to make my own airbox, but I'm not that talented.

[bkm]

This project is taking a slightly different path. Here's the new direction.

[bkm]

If anyone is interested in the kdx/kx engine I'm probably going to part it out on eBay, but I'd make someone on here a hell of a deal, but it is in pieces.

[tecaterob]

Which motor is the new one and what bike. Head is thick as hell.

[bkm]

1986 kx125.

[250rmanfmf]

I thought that looked like a kx125. Looks sweet and I bet it will rip. Very nice