Speaking from experience, a motor is cheaper and a whole lot less work.
I'm rebuilding because it's easier for me to spend a bit here and there as I go. If I could just drop the coin on a motor all at once, I probably would have.

 

I looked on ebay, not much there right now

 

I'll try this short version first in case the moderator rejects the post again. If successful, I'll provide some description next.

 

Okay, it worked this time.

I found the missing hunk of metal from the tensioner body. It fell from an unknown resting spot while the engine was on the bench being tore down. I was surprised that it is un-chewed. I was guessing this was the cause of the missing teeth from the cam gear on the crankshaft. A new guess is a sloppy timing chain is the reason for the missing teeth.

-There is a fair amount of carbon on the piston and head. The engine doesn't smoke so I believe this to be due to crankcase gasses being fed back into the intake. The new engine will receive a crankcase ventilation filter instead.
-The lines on the side of the piston look like scratching, moving my finger across them, I don't feel anything.
-I don't see any flat spots on the cam lobes.
-I can't detect any galling on any surface

Everything else looks really good. Let me know if you see any problems and I'll check it out.

 

ya, mostly looks pretty good & should clean up fine. measure everything to be sure they are still in limits, but looks like it will make. pull the oil pump and be sure it's clean and undamaged inside. the screws have thread locker & probably need heat to break loose. I haven' looked, but i doubt there are clearances given for the pump gears. check them anyway for scoring etc. a clever guy can lap minor damage out of a pump. as for cranks on fleabay... looks like one that would fit....

https://www.ebay.com/itm/Kawasaki-KL...8AAOSwTHNc3Nkj

I have no affiliation with this seller and no knowledge of condition. can't go wrong with new. in any case, good luck

 

Throw that ebay crank in there for sure! I would pull the valves, clean up the combustion area. Do a lite lap to verify contact area. Should be middle 1/3rd of the valve face. I use 1200 grit lapping compound. maybe throw in some valve seals? Your crank journals look fine, so do your cams. I might throw a new timing chain in there due to the "trama" it may have experienced taking off those teeth on the crank. Inspect the cam gears for damage. Not sure about a crank vent filter?

Throw it back together and beat the hell out of it!!

maybe press off the KACR?

maybe a auto chain tension-er?

 

I just noticed the seller. I purchased and just received a chain and sprockets and a chain guard from this seller. The chain/sprockets and guard was from the same bike. pretty minty. Seller States 1300 MI. Normally I don't buy used chains and sprockets but in the pictures it looked new and when I received it looked even better. this bike had a pretty easy 1,300 miles so that crank should be damn near mint. EBay has an amazing buyer protection policy if you just say that was not as advertised the seller has to take it back so I think you're pretty safe

 

The case is split. I have a couple concerns,

1. One crankshaft bearing remained on the crankshaft.
2. The crankshaft slid straight out of the bearing on the other case half.

I had read that these bearings need to be pressed in/out and preferably with the application of heat. I'm a little worried the bearing seats are out of tolerance making them sloppy and the bearings spin in the case. The condition of the crankshaft bearings is really good. No slop and they spin smoothly.

I didn't see the cam teeth anywhere until a little oil drizzled out of one of the cases and two of the four teeth were there. Two down, two to go.
Many of the smaller bearings are trashed/don't spin smoothly. A slight catch is felt spinning them by hand.

There is an oil passage where the balancer shaft sits in the case. There is small amount of gouging in the case that can be seen with the shaft removed.

 

When mine had the crank failure years ago, I made a support collar/spacer from an appropriate sized pvc pipe coupler that I trimmed to fit over the l/h side of the crankcase. With the spacer on the bench and then the crankcase set over that with the collar centered over the main bearing cavity, it will allow you to tap the race into the case. I found that if you freeze the bearings and put the case in a 250degF oven, it almost falls together. I'll see if I can find the spacer I made and take a pic.

 

GB - Yeah, I saved my old electric oven just for the occasion. Actually, it was so I could do my own power coating. I have yet to do it.

I have looked at what's available on ebay and didn't like the condition of the cranks there. They just look burnt. Looking at mine, it is still shiny despite the broken cam gear teeth. The new crank from revzilla is on its way.

Question, the new timing chain purchased is silver and feels lighter than the original. The materials used in the construction of each is not mentioned anywhere so I can't determine the strength of each.
Does anyone have experience with replacement chains?