Re: Do i need to bolt my motor on?
The lock bar that Expedia posted is all you need if you leave that boat/motor outside. It also keeps the clamps from loosening and is cheap. I don't know what you are all doing wrong with your boat motors that you can't keep them on the transom. Don't scare the guy. I'm sure that you did have some motor mishaps, but those are pretty rare occurrences, not the norm.
The question was do you need to bolt it on? The short answer is no, it is not NEEDED. The full answer is that it depends on personal preference, where you store the boat, whether you plan to keep a lock on it, and whether or not you follow up on safety procedures before boating (such as verifying that the motor is securely attached prior to use).
Good luck.
Agreed. The manufacturers would not make these small outboards with a turn buckle clamp if they tended to pop off the transoms. That would be a quick class action suit for poor design. None of the boat rental places worry about clamping them on. You want a 25hp or a 5 hp. They just clamp one on the your rental boat and off you go.
The 99 25 hp 2 stroke I use that locking bar on was bought originally for protection for a Merc 9.9 from being swiped off another rig I owned. So when my Daughter picked up this 25 hp O/B I put that locking bar on first thing. More for protection cause small O/B's are prime targets for thieves. This O/B actually has two bottom bolts going through the transom too.
I know this because I have to raise it up 2-3 inches and that's going to put those upper clamp circles right at the top edge of the transom. I'll make an aluminum or plastic block to raise it up, but I'll definitely drill two new holes because that top clamp will be so high towards the top of the transom it makes me nervous just to have to take it for a test ride without the bolts back on.
It's only the first hole that hurts

Start with a small drill bit and first drill a pilot hole. Spend $10 and go to home depot and buy a new bit the size of the final hole you will need. Go to West Marine and pick up 2-4 stainless steel bolts, washers and those brass lock nuts. These can be probably found in Home Depot too, a lot cheaper than West.
So bottom line, drill the holes for safety and buy that locking bar for theft prevention. A $35 total outlay is cheap insurance than having to spring someday for a missing outboard either stolen or sitting on the lake floor

Or you could pay a dealer $90 an hour to mount it properly for you!