Forget push-up bras, keg cans, iPods and 52-inch flat screens…for my money, outboard jets have to be one of the best inventions of all time. I mean, anything that allows me to blaze 30 mph through 2-inch shallows is definitely on the short list of cool stuff to own.
But on the other hand, there are days when I want unbolt my outboard and use it as an anchor. Talk about an inefficient way to propel one’s self upriver! Outboard jets are about 30 percent less efficient than their prop-driven cousins…and that’s when the stinking thing is brand spankin’ new. After some good use, the output goes down even more.
Luckily, there are some things you can do to help make your outboard jet run like new again.
With an outboard jet, most of your bottom strikes are going to occur right on the grates on the underside of the shoe. Once good “thunk” on the bottom can bend several of your grates. And it’s pretty simple – the more bent up those things are, the more the motor has to suck to get water up inside. Luckily, it’s not to big of a job to tap out the two pins that hold the grates in place and then either replace them with new ones or pound them straight again.
Regardless of whether you straighten out the old grates or buy new ones, a cool trick is to sharpen the edges of each one. With a bench grinder, sharpen the leading edges of each one to a triangular point.
You’ll also loose plenty of power if your wear ring (sleeve) is worn or grooved. An outboard jet works best when the outside edges of the impeller blades are as close to the inside edge of the wear ring as possible without rubbing.
When you’ve got grooves in the sleeve, water gets sucked around the outside of the blades instead of over them and that will cost you a noticeable amount of horsepower.
Probably the best way to ensure that you maintain your highest level of propulsion is to purchase and install a new wear ring (about $50).
If you use your boat at all, you’re going to eventually suck up sand or gravel. Hard, rocky material running over the blades of your impeller will result in dings, divots and a general dulling of the leading edges.
Kinda like a dull steak knife, worm impeller blades have a tough time cutting through the water. And like seemingly everything else in this game, little imperfections can cause big decreases in performance.
With impellers costing several hundred bucks, you’re probably not going to be replacing them very often, so the next best thing is to sharpen up the blades. It’s a pretty simple affair, but it does take a little concentration.
Take a file to the bevel side of each blade and work inside out with light strokes. You don’t want to take too much material off or you will be ordering a new impeller. The real trick to this game is to take the same amount of metal off each blade. To do this, count your strokes with the file and use the same amount on each of the blades.