Timing chain trouble on a tare down

[Swany10]

I'm trying to do a tare down of a locked up 85 250es motor I got on a parts bike. I've never done this before, so forgive me if I'm missing something obvious. I need to get the timing chain off and I can't seem to do it. I took the tensioner off, but there's not enough slack to get it off. I also wasn't lucky enough to have the sprocket be in a position where both the retaining bolts are accessible. I was really hoping to do a top end rebuild only on this motor as I'm guessing it's locked up from sitting outside, but the only way forward I can see is to break the chain.

Anyone have anything else I could try? Also, I watched a video of a 250sx motor tare down, that guy only had to remove the tensioner to get enough slack, is my motor weird or something?

[Swany10]

I've been trying to use the search to find out more on what I can do here, but I'm not very good at using it yet.

So far I've found a post that says while installing a new chain you have the cam sprocket unbolted to have enough slack in the chain. If my chain is not stretched out, this would explain why I don't have enough slack to take it off. Unfortunately, since I can't access both the sprocket bolts, and have no way of getting the piston to move, it looks like I'll be having to buy a cam chain breaker.

Sound like I'm on the right track here or is there something else I could try?

[shortline10]

Did you try turning the crankshaft back and forth at the flywheel ?
I’ve run into this situation several times , the last one I was able to pick up on the back side of the cam and put it at an angle just enough to pry the chain off without hurting anything .

[Swany10]

I haven't tried that, but it sounds worth trying. I'm not too hopeful though, when I pulled the spark plug I could see the piston is rusty, I'm guessing this thing is locked up hard.

[shortline10]

Put plenty of penetrating fluid down the plug hole to try and free up the piston

[Swany10]

Duplicated this post and got more traction on it here:

http://www.3wheelerworld.com/showthread.php/191836-Timing-chain-trouble-on-tare-down