How can I make sure a motor I got to replace the one in my brat is at TDC?I got the motor with no flywheel,no disty,and no alternator,and no carb.I have a weber and the alt of my brat but I need the motor at TDC before I can install the disty.so how do I do it?

Remove valve cover for #1 cyl. Rotate engine (wrench/socket on crank bolt). Observe valve movement and watch piston through spark plug hole. When both valves are closed and piston stops moving up, you are at TDC (or close enough to crank and fine tune later). Make sure disty rotor is pointing to #1 position after installation.

 

or......

 

With flywheel installed, rotate engine (correct direction) by hand with finger over #1 plug hole. On compression stroke, air will will be forced out under you r finger. Right when it stops pushing air out, stop rotating. You are now close enough to install disty and crank for final timing adjustment.

so the flywheel can only go on one way?

Yes, if you look at the bolt pattern on your flywheel, you'll notice a couple of the holes are closer together and a couple are farther apart. This is so you can only bolt the flywheel on in one position.

 

-Brian