TOPIC:

I JUST found out that my donor motor for my KZ1300 with a bent rod is not as good a replacement as I though- namely, it's locked up. Now, I'm hoping that it's just got some stuck rings from sitting for years.

That being said, what would be the best way to grab on to the crankshaft and start to work it loose? Typical way to turn the motor over by hand is using the stator bolt, but using it to break the pistons loose is out of the question. My dad has access to a large strap wrench, but what would be the best place to grab it- around the actual stator, or come at it from the other side, clamping around the torsion damper on the left side of the engine?

Simply off the top of my head (no Pun intended) I'd be very weary of bending other rods, in trying to turn it over with excess leverage !

Well, if it's stuck then the piston rings have welded themselves to the cylinder walls. I have heard of a lot of mechanics breaking the engines free by putting diesel fuel down the sparkplug holes and letting it sit for a couple of days and then a wrench on the crankshaft bolt and rocking the crank back and forth GENTLY, but if the rings have welded then even after you've cracked it free the rings are pooched and the cylinder bores will need to be honed at the very least.

You're going to be pulling the cylinders anyway so if I were doing this job I would remove the cylinder head and soak the cylinders with penetrating oil or diesel fuel for a couple of days and then take a hammer and using the butt end of the handle gently tapping the top of the piston front and rear to break free the pistons which are seized. Most likely there is one or two that are stuck and the others are free. By doing this tapping method you're breaking the pistons free without adding any stress to the rest of the rotating parts.

Okay, so, bit of clarification- the motor that came with my bike is toast. It's currently in about 4 different boxes, and has several hundred dollars of work left if it even wants a CHANCE of working again.

Which it won't, because I found ANOTHER motor on craigslist for $350. Unfortunately, I somehow never asked if it was actually FREE, because it wasn't. It was locked up, probably from sitting- it's a 1979 motor with only 18K miles on it.

Anyway, I DID actually manage to break it free- mostly. I was able to thread some class 10.9 bolts into the torsion damper on the left side of the crankshaft, then use a crowbar to rock it back and forth. I've got about 270° of rotation, but that last 90° is still stuck. At first I thought a valve was hitting, but I managed to get it to TDC, and the cam timing is good. It must just be crud in the bore. Transmission and secondary shaft is all free, it's just the pistons giving me trouble.

I've got some Marvel Mystery Oil soaking into it right now. If that doesn't work, I'll up my game to a 50/50 mix of acetone and auto tranny fluid. If THAT doesn't do it- off comes the head, and possibly the bores as well.

I have heard of people using brake fluid. I have used water and molasses mix on rusty metal tools and parts etc before and was surprised at how well it worked but that was by submerging the rusted objects for a week or so.

Lucien, you need to be patient. Let the penetrating oil do the work. PB blaster and wd-40 are comon choices, marvel oil will work. A 50/50 mix of diesel fuel and automatic transmission fluid is one of the best for freeing the rings.

Let it sit for a day at least. It should break free with a little effort. I have had stuck engines come around and run again. After you get it free look down the clinders with a flashlight and see how bad the pitted are is where the rings had frozen. It should be just a ring around the cylinder, and thats not a big deal. If its more then it may have been damp where it was sitting.... not so good.