Help ZXR250C - Rebuild V2

Sorry to hear about your dramas.

Any metal in the sump is not good.
As Andy mentioned, it looks like an engine out exercise.

I am not familiar with that engine, but I wouldn't imagine that you need to split the cam chain.
But you will need to remove the tensioner.
On other bikes I have worked on, with the tensioner, removed there is then enough room to undo the cam caps and lift the cams out while feeding the chain over the front of the sprocket.
Refer to your manual for full details.

With the engine out all the work will be much easier and you will have much better confidence on its condition when you put it all back together again.

Make sure you clean all of the oil holes/galleries out thoroughly when you put it back together again.

Peter.

 

Not sure about that motor design, but typically these older motors have the crank and gearbox on the same plane.
When you remove the lower portion of the crankcase it also results in splitting the gearbox.
I have in the past been able to turn the engine upside down and then split the crankcase without removing the cylinder head or pistons (GSXR motor). I am not sure whether this will work with your motor.

You are probably best just to pull the whole thing apart. You will probably want to inspect the pistons.

As long as you are careful you can probably lift out the gearbox input and output shafts as complete assemblies (once you have split the cases) and just hold them all together with cable ties or tape. That way you do not have to worry about getting the gears mixed up.

 

Just looking at your #3 spark plug (3rd picture), it might just be the angle of the picture, but it looks like the the outer strap is touching the electrode. This might indicate that the piston has hit the plug and maybe the valves, or there have been foreign objects in the cylinder.

Regarding your cam chain, how does it feel when you press up and down on it? If it feels tight then it's okay, if it has any free play or slack it probably needs a new tensioner and perhaps chain unless done already.

It's hard to tell from the picture but all that crap in your oil pan looks like metal flakes rather than silicone, so not good. In any case the sump, strainer and oil pump will all need a good clean out.

Now for removing the cams, line up the timing marks as per your picture and remove the tensioner, then rotate the crank forward slightly to relieve tension on the chain. From this point you can remove the camshaft cap(s) and lift one of the cams out. You'll have to maneuver it a bit to get the chain off the cam sprocket.

I never did a full strip down on my ZXR but I did take the head and cylinders off, I can't recall if you need to do that to split the cases. In any case, your engine looks like a candidate for a full tear down. Once you have the cams out, I would be pulling the cylinder head off and inspecting the cylinders. From there you can just pull the cylinder block off and that gives you access to to check the rods by hand - up and down play or excessive side to side play = dead rod bearings.

 

That gap does looks pretty close to me. Can you get a feeler gauge in there? Are there any signs of piston contact on the plug?

 

You should pull the head off and look at #3 cylinder

Out of curiosity what plugs are they? Should be NGK CR9E