Engine Trouble YD-100 not starting after teardown

Dylan57

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I recently did a complete engine teardown and replaced all the gaskets on my YD-100, I haven’t been able to start it since. Fuel and air is getting to the cylinder, there shouldn’t be any air leaks on the carburetor side. It’s getting spark, and the engine has normal compression, based on feel. Not sure what else it could be, so figured I’d make a post.
 
With the mag off, the notch in the crank should be at the 1 o'clock position when the piston is at TDC. You will still get a spark if it's not, but not at the right time. Easy mistake to put the mag on backward.
 
I made sure to put it in the same position as it was in the video that BikeBerry posted about Splitting a case in half, but I guess there’s no harm in trying to flip it.
 
I made sure to put it in the same position as it was in the video that BikeBerry posted about Splitting a case in half, but I guess there’s no harm in trying to flip it.
No need to flip it over if it checks out, remove the nut, and you can see where the key slot is at relative to the piston.
 
Which direction should the woodruff key be facing relative to the piston?
The curved side goes in the curved slot in the crank. Put a thin coat of oil on everything and tap it into place with the handle of a screwdriver or something keeping the top of the key parallel to the crank.
 
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