Both spark plugs were in tight. So I sprayed some carb cleaner in the holes and waited a couple of hours. The front then came with just a little effort. The back was still tight so I decided to spray more carb cleaner in it. This time, I noticed the liquid coming out the left side of the cylinder. When I looked closer, there appears to be a "seep" hole that looks like it could line up with where the spark plug is screwed in. It looks to be perfectly round and not cracked or chipped. Can someone confirm theirs has the same hole? If so, I'm wondering if it is to permit any water to run out if it is left out in the rain, since the bike leans to that side. This could also explain why the rear plug didn't loosen up like the front, since the liquid didn't have a chance to soak in.