Well, my friend ... what are the possibilities of you being hired into a position from your former career path of 15 years? Your resume' would be pretty strong with that experience behind you. If there are employment opportunities there for you, it certainly would be prudent to apply for the available positions. Changing careers is always risky, but rewarding when it occurs. I have made complete career shifts 5 times, and each one has been a blessing and an opportunity for growth. You can still pursue a "change" even when occupied in any given job, so even if you return to your former career, God can open other doors.
100% commission sales positions (I worked in that realm for 9 years) can be good, but there are usually lean times. It is best to have a REAL passion for (or belief in the product) whatever you are selling, in order to transmit that excitement and "sense of urgency" to the prospective buyer. It can be challenging. As for motorcycle repair: Are you good at it? Do you enjoy it? If so, you can market your business locally and create a very inexpensive website to enhance your visibility and marketing. I would recommend doing some research on the Internet to determine who your competition is in your area, what the going repair rates are (so you can establish a favorably competitive rate) and even determine how many motorcycle owners are in your area (through sales statistics from local dealers, motorcycle clubs, etc.), types of motorcycles owned (to see if there is a great enough need for your services) and then determine if you have the knowledge and ability to service those needs. If you have a few motorcycles available to repair (friends, etc.), that could be the beginning of your grassroots marketing, and put food on the table.
As for God's direction in this: Does your church offer any help at all? You might want to speak with a pastor at your church and tell him of your situation. I do know this ... in the matter of priorities - it is always God first, family second and job third. And as stated in Matthew 6:33, "But seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you.", when you seek God, he will direct your path. I know He wants the very best for your family, and He wants you to take care of them. God can open any door - the most important thing right now is not WHICH job you do, it is finding a job that will attend to your family's needs, embracing that job, and honoring God as you perform the job to the best of your ability. Be anxious for nothing my friend, just be diligent in seeking opportunity. Keep praying and seeking God, and remember - especially since much of your financial status seems to be upside down - the specific JOB is not the real question - it is "What can I do to meet my family's needs?" Honor God in this, and He will open those doors.