There are thousands of moto racing games for mobile platforms. Most of the simple bike racing games are trending on google play with millions of downloads. Check out the keyword yourself.
*Easy code learning
*Easy to reskin
*Made on Unity
*Unlockable items with coins
*Port to any other unity supported platform including iOS, Android, Flash, Windows phone etc
See documentation with purchase.
Documentation and 24/7 support is provided with the purchase.