03 KDX220R

I stepped my 15yo up to a full size dirt bike and had him do most of the maintenance it needed.
front wheel bearings
front brake pads
bled both front and back brakes
new fork oil
topped up the coolant
replaced a stripped mount for the LH bark buster
replaced Chinese footpegs with OEM and 1 new return spring
replaced gear box oil
air filter clean and oil
secured loose tail light
new chain & sprockets
new front chain guide and sprocket cover
now its ready to rip.
Over the winter the suspension linkage and steering stem should be re-lubed.
I've read the OEM piston is a grenade waiting to go off, I suspect it was already done since it came with a used head gasket.
Not a Yamaha but it will be running 2-stroke Yamalube I have an abundance still on hand.

 

Kawak makes darned good bikes overall. Definitely keep an eye on the piston. Since the stocker tends to crack, teach your kid about what a soft seize feels like. It'll be about the same (sudden "softness" in power delivery).

 

I need to teach myself - soft seize, never heard the term before.

 

It's a 2-stroke term. When the piston melts just a little due to lack of lubrication along the skirt, or overheating which gives the same effect.

Although... I can't remember exactly how the KD piston cracks....if it's radially along the wrist pin the failure will be.....more than obvious.

 

I just finished my annual father and son camping/riding trip.
We settled on a 35 km loop through the forest and did this 3 times each day, 3 days in a row.
On the 1st day we lost the kicker for the KDX, I retraced the loop and found it about 10 kms from the camp laying in the trail, huge relief.
Felt like finding a needle in a haystack.
We saw a moose running our same trail, my son couldn't believe how huge they are.
This one was without horns, not sure if it was a bull or a cow but it ran away.
I've encountered one on a street bike and it stood its ground and looked like it was setting to charge until my riding partner came along.
He's 16 and I'm 60 so he's egging me to do one more lap, keeps me young.


no Yamahas but we did burn Yamalube in the Kawasaki

 

Good times. Memories for a lifetime . Where did you camp ? It looks like neat place.

 

A trailer park on Lake St Peter, they keep just a few sites open for tents, really lucky to get a spot. Super clean campground with great beach.

 

I would think the moose would have growing horns by now. I know our deer and Elk do down here in Wisconsin. No matter what it was, they are so cool, huge and majestic. 60 and still on the dirt bikes, good for you! Those are great bikes too.

 

Thanks @Timbox I can't praise my KTM enough.
2005 EXC525 I bought new.
Shortly after the electric start ate itself and shredded the pinion gear leaving nasty shards in the motor.
It has 2 SS mesh screens and 2 paper oil filters plus the typical magnetic drain plug so over the course of several oil changes I got it all out.
I installed 2006 parts and all is good, 2005 was obviously a weak point for this.
What's not to like about a 240 lb (dry weight) bike with about 50 hp on tap!
Take your bad-ass 450 moto crosser and add another 60 cc's just for giggles. (they're actually 510).
I have 3 sets of wheels for it - mud, gravel and supermotard.

 

It's cool that the trailer park let you ride bikes on the property. Most parks make you push your bike to your site even street bikes.

 

Teaching my kid more wrenching skills.
On our last trail ride the KDX fouled the spark plug but I noticed it wasn't soot but remnants of coolant.
I thought maybe it was just the head gasket leaking but didn't see any evidence of that when I pulled the head.
I saw some melting of the piston crown so decided to change the piston.
Big chunks of the skirt are broken off and you can actually see bits stuck in the conn rod.
Need to continue stripping the entire bottom end to get all the shrapnel out and inspect the cases.
I suspect damage to the cases down by the water pump, coolant was getting into the motor somewhere.

 

To strip the bottom end I had to wait for some case splitters and a flywheel puller. That took 5 weeks.
What I found was not good. When the piston skirt broke off it went around the crank, breaking the RH case near the bottom of the stroke.
The LH case shows some damage there to.
I'm not sure if I want to try repairing these cases or get some used ones off eBay.
Last night there were 2 sets of 220 cases but a whole bunch of 200 cases.
I don't think there is any difference in the 2 bottom ends so the 200 will work.
I don't understand why we had coolant in the combustion as this broken piece just opens the crank cavity to a dead space,
the bike is still able to run like this.
At this stage I can rebuild the motor with used cases, probably going to be $1500 or the other option is to just part it out.
I have a new piston already, it will need the crank rebuilt, new bearings, oil seals, gaskets etc.
I could slap it back together with a new piston and JB Weld but I'm too ethical to sell it like that.

case splitters are necessary. Do not attempt to split vertical cases without them.
Works real slick pulling the cases off the crank bearing.
I also have another tool to draw the crank back into the cases.

below you can see the piece broken off.
It opens up the crank to the dead space below so the motor still runs but it increases the crank volume, this would lessen the pressure pushing the next charge up through the transfer ports.

 

My local bike/machine shop says no problem fixing this case.
I'll be dropping it off with the crank shaft and get a new conn rod and main bearings installed.

 

the shop weld repaired the cases, ground them to fit each other and coated them with an epoxy.
He said if there are any cracks still there the epoxy just helps seal them up and stops them propagating, he knows his stuff.
That was $157 and he charged $99 to rebuild and true the crank.
New Pro-X rod, crank bearings, oil seals, gaskets, piston and rings.

 

Looks nice. I used to weld case/cover cracks for a co-worker who worked on Harley's at home. Not much fun.

 

I just found out my new crank installer does not have an adapter to fit the threads on one end of the crankshaft. I ordered the actual nut from Kawasaki and I’ll need to grind it down to fit the tool. Another 2 week delay. 16M x 1.0 is a real fine thread, the local fastener warehouse has nothing like that.

 

My ambition for today is assemble the rest of the KDX motor. Clear the work bench for XJ motors.
I took it apart 5 months ago and all I have is the exploded parts printed out, wish me luck

See the 1” pipe nipple in the picture, I discovered it’s the perfect dimension for tapping new Kawasaki water pump seals in.
It was $2.69.

 

Didn’t quite make it.
Bottom is together, shifts and the kick lever works.

 

KDX motor is finally complete.
I never did a complete disassemble of a 2-stroke before so I had to buy the tools for separating and reassembling vertically split crank cases. Also bought a flywheel holding wrench which I finally made use of.
Shouldn’t be much more than another evening to get the bike back together.
My son will do that with dad’s supervision.

I bought another tool chest and organized all my tools just like I should have done years ago.
It’s a pleasure working in the garage again.

 

Satisfying work, well done.