There is only one road all the way through the park you can take on a motorcycle. It's about a 10 minute ride you do see a lot but not all of the park. It's a good ride though and lots of good road before and after the park itself
Yes you may ride through the motorcycle in Zion and go through the tunnel. But, you will need to park and ride the shuttle to explore the park. There are SO many places to explore in Zion! How long depends on how much you want to see! One simple trail you may enjoy is the river walk. It's at the end of the shuttle ride. It's paved and about 3/4 of a mile one way. It ends at the mouth of the narrows.
On my last visit to Zion, there were many motorcyclists, but I don't know how long it would take to explore by motorcycle.
Well, I have never seen people riding motorcycles.
Thanks! Your answer is awaiting moderation.