So I blew up my motor last August. I thought I had a slight case of piston slap, what I really had was rod knock.
Come to discover you can't buy a rod, you have to buy the whole crank assembly for $500.
So it's time to split cases.
The shift shaft assembly is the last thing to remove before I start pulling case bolts. It was late last night when I got to that point and called it a night.
Once the cases are split and the crank is removed, I'll be ready to start putting it back together. I'm going to replace all the bearings. Probably not necessary but with 64,000mi on the bike and it totally torn down it seems dumb not to do it. It would suck to rebuild and later have something I didn't replace cause a failure.
The frame has some issues as well...
I rode the poor beast 12mo/yr for 3 years in northern NH through snow, salt, and sand. I washed it every week, but that just wasn't enough. In the one spot that I could never really see or clean I have a whole in the frame (surprise, surprise) about 1/2" wide and 2" long. At least now I have a real reason to buy a welding set-up.
I'll try and post some photos once the cases are split and I'm putting things back together. I hope I took enough pictures and made enough notes.

Here she is broken down enough to get in the car.



And in the same state unloaded at my friends garage.



And finally broken down after 8hrs of work.


And a pile of parts.



The whole lot got thrown back in the car and taken down into my basement workshop to be cleaned and reassembled.

 

Keep us posted!

 

Looking forward to following this one, take lots of pictures!

 

Have you compared the repair costs and resale value vs buying a new KLX250?
There also is the risk of the rebuilt engine failing vs a new bike warranty.
Did you come up with numbers? What were they?
Not being a jerk, I am curious and too lazy to do an analysis since my bike is OK,
but if/when my bike grenades I will have some knowledge from your experience.

 

@snappster - First, my thought is that there is no resale value in my bike as a whole (and working bike); too many miles and scars. A new KLX is out for me for a few reasons, but mostly because if I got a new bike it would be a 450 of some type.
I'm not too worried about a rebuilt engine. Now I'm no mechanic but I do have a torque wrench, skills, can follow directions, and when needed, help from a real mechanic.
I'm finally going for the BB big bore now that I need a new piston and jug.
Still trying to find someone to rebuild the crank I have. Hopefully that will be less than 1/2 the cost of a new crank. If I do need to buy a new crank then so be it.
I didn't really do the numbers but a rough guess is that it will cost the same or less as a used bike. Since I'm doing most of the work the cost to rebuild is time, which I've got. And I feel like I owe the little KLX for all she's done for me and want to do the full rebuild just for my own experience and hopefully satisfaction(once it's working again).

So for the numbers I know about:
Crank - $476 new, rebuilt unknown cost
Bill Blue BB - $533.95

And the numbers I don't know about:
Bill Blue head port and polish - $???
Gaskets - ~$200 it's a guess, I need all of them but two I already have and those that come with the big bore
Bearings - ain't gonna be cheap buying Kawi parts but sourcing them from a bearing company might not be so bad
Seals - shift shaft, water pump seals, drive shaft, kick start
Air box boot and the piece between the carb and engine
I might try and make a new oil line just for ****s and giggles, never liked the hard line that is stock.
New valves and springs - definitely springs, not sure about the valves

Now my ace in the hole is that my company, which sells bicycle parts, has a reciprocal deal with a motorcycle shop. That means parts at shop pricing + shipping = cheaper than I could get them by myself. So a new crank might not be $476, we'll see.

My biggest worry - left over parts! LOL There are so many! I've bagged and tagged each little part. The bags say what it is and where it goes. All those are separated into categories like frame, top end, bottom end, etc.

I know it won't be cheap but life experience never is...

 

Check with Carrillo to see if they might have a rod that would work? I'd press the crank apart and do the measurements, then call Carrillo. They do one that fits the KLX650 which is way less common.

 

That's some impressive mileage on the klx. I'm at 67,000+ on my 94 klr250 and it's starting to get a bit noisy as well. I'm not sure how many more miles I'll get out of my klr, but I would like to get 100k out of the little 250. I have an 06 klx with the Bill Blue 351 kit and like anyone else that has his big bore kit it really makes a world of difference on the klx. Post some pictures of the engine rebuild, I've rebuilt a few different klr250 engines over the years and if the klx 250 engine is anything like the klr it's a simple little engine to work on.

 

MP-sorry to hear about the demise of the engine. I wasn't able to find any aftermarket or oe sources for rod bearing or conrod when mine hammered out the big end . Just lay out the $450 for a new crank and move on. I wouldn't go any further on the head beyond a valve job w/valves and springs. Cleaning up casting flash and matching to manifolds are the only port work I would do-definitely not worth spending any money on. Disassembling the engine is pretty straightforward-the only tools/fixture I had to fab up were to press the crank into the cases. Throw the cases in the oven and the crank in the freezer and it should fall together. Let me know if I can help.

 

what sort of noises was the motor making when you thought it was just piston slap?

 

@horror fan It made an extra tick when it hit the top or bottom of the stroke, it was only really audible when the starter was turning over the motor. Everyone that heard it thought the same.

So my question for those that have been down this road. How do I pull out the transmission? The book says yank out both shafts of the trans together with the teeth meshed, that isn't working for some reason I looked for a circlip I missed, but didn't see any.
The output shaft is the one that won't move.