wrong isac i thought that to but in the book it says it tdc on the top of stroke and the bottom of stroke i assumed that ,pulled a plug stuck a screw driver in it to fell it ok its at top .good right wrong thats the exaust stoke (blowing out the pipe) it need to be on the bottom ......i guess this has to do with over head cams or something because on my ta i swear i set it with the piston at the top .but that is a single cam with push rods ima look into this

 

now with that being said who needs to know where a bolt is on this motor ............lol ive unscrewed everyone of em 6 times

 

there will be 2 TDC for any given 4stroke motor.
one TDC will be at the end of the compression stroke beginning of the power stroke as the plug fires

The next TDC will come at the end of the exhaust stroke as the piston reaches TDC the exhaust closes and the intake opens for an intake stroke.

The is just the design but to make it work in your head just look at the pulleys. The bottom one is very small and the cam pulleys are much larger.