Crankshaft position and timing

This is bothering me and I think I understand it but I'd like some input or correction if I'm wrong. When setting the timing, it's important to know which direction your flywheel spins when you go forward. Knowing that, there are two positions you can set your piston at 2mm btdc. Before top dead center. My crude drawing of both positions, show the direction my flywheel spins when attempting to start my bike. I don't understand if I want to crankshaft in position 1 or 2. Btdc would be position 2? Wouldn't this push the wheel backwards and run the bike in reverse? I've heard of this before. So don't I want position 1? Or will the crank rotate through combustion at position 2 and push the crank in the correct rotation?(edited)

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Re: Crankshaft position and timing

Based on that drawing and the rotation of the crank, looks like position 2 is where you want to fire because it is BEFORE Top Dead Center as the crank is rotating. Position 1 would be as the piston is traveling back down so would be AFTER Top Dead Center in the stroke

Re: Crankshaft position and timing

Yes, if I understand correctly, the spark goes off (2mm) btdc and the piston continues to compress through combustion and then comes back to position 1 and creates rotation and power?

Re: Crankshaft position and timing

The spark fires BEFORE max compression?

Re: Crankshaft position and timing

Yes and yes to your last two questions . ;)

Re: Crankshaft position and timing

Awesome. Thanks

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