Hi, I recently reassembled my first 4 stroke - a Saito 72. The engine is fine, runs as good or better than before.

My question is about engine reassembly, specifically, the alignment of the cam gear. The instructions are as follows:-

"Assemble the cam gear lining up the timing mark at the “6 o'clock” position. The crankshaft must be positioned at the “12 o'clock” or “top dead center”

How accurate can/must I be?

First, in getting the crankshaft to TDC and second, in setting the cam gear bench mark in the correct orientation. Is a visual alignment sufficient? Do I need to think about making/purchasing some tool? I tend to work slowly and can be pretty careful with these things but it occured to me that even with my best efforts, I might still be off. Is this something to worry about? Or perhaps the gear teeth do not permit the kind of resolution that makes all of this a real problem?

Thanks!