350x timing and TDC?

[Super350]

When you are putting the timing chain on the cam sprocket you have to line up the "T" mark on the flywheel w/ the slit in the left case cover, make sure the punch mark in the cam sprocket is "up" and line up the 2 marks on the cam sprkt w/ the flat of the head itself. My question is when the "T" is lined up is that always TDC or can it also be at the bottom of the stroke and if so how do you tell? You cant rely on weather or not the rockers are both loose b/c they havent been installed yet. thanks guys

[HONDA_ATC_FREAK]

take out your spark plug and look at the piston if your not sure.

[wonderboy]

TDC = Top Dead Center: By definition, the piston is at the top of it's stroke. The piston will not be down. The flywheel is tied directly to the crank, so the piston can't do something different from revolution to revolution with respect to the TDC mark on the flywheel.

What may be confusing to you is the fact that the camshaft speed is half the crankshaft.

Don't worry about the rocker arms right now, because you are just now installing the cam. By lining up the marks like you described (which I'm assuming is from the manual... I didn't verify what you said) you are establishing the proper phasing between the crank and cam so that the valves will open and close at the proper time.

The trick about checking if both rocker arms are loose is to confirm when the piston is at TDC on the compression stroke. You need to do this when you set the lash on your rocker arms. The rocker arms are loose because on the compression stroke, both valves need to be closed, so the cam is not pressing on the arms at all. The other time the piston is at TDC will be at the top of the exhaust stroke, in which case the exhaust valve will be open (so the rocker arm will feel tight).