3 Tips to help improve your outboard jet’s performance

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.



Intake Grates

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.

Grind a knife edge into your grates and the jet will suck more water

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.

Wear Ring

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.

This isn’t helping!

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).

The old and the new…big difference, huh?

Impeller

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.

The impact zone

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.

Just like new again!

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.

Did you enjoy this article?

If so, sign up today for my newsletter to receive regular fishing updates, news, gear reviews and more! Click the blue button below:

Click Here to Subscribe

Comments

  1. Garrett says

    I need a part number to order a stainless steel 4 blade impeller for my mercury jet20.its a 1996 model

  2. STO says

    We just purchased a 13 foot Jon boat (Wide) with a 30/25 Mercury EFI Jet. It seems way underpowered. However, before we made our purchase, everyone said it would be more than enough power, if not too much. We need a little help!! The boat has a max HP rating of 20HP. It barely gets up on plane. HELP!!!

    • doug says

      I bought a 60/40 merc a few years ago and love the thing its on the river every weekend , my problem was that the marina set it up WRONG . after I looked into it i found that the height was an inch to low. after I adjusted it where it should be I gained almost 5mph it incressed to top speed of 27 mph upstream then added pods and a splash sheald l gained another 3 mph . now the guys are doing the same thing to theres cause they cant keep up with the trim set and adjusted correctly the thing scoots

    • joe says

      Likely you have too much weight at back of boat. You have a 30hp, weighing what ever a 30hp weighs, but only putting out roughly 20hp. Do what I have done and get as much weight out of the ass end of the boat. Gas cans, batteries, gear should be moved as far to the front of boat as possible. This includes gear, humans when you are under way, anchor, steering console if you have one. Also center these things, from left to right for good balance.

      I predict this will solve your problem. Joe

    • sandro says

      Make sure your getting proper rpm out of motor and its running properly. Next check reverse gate is not interfering with pump output, check impeller and liner for wear and improper gap at impelled to liner

  3. tom says

    I just bought a 17 valco with a johnson 65/45 jet. i have driven jets before but this is my first one. It really pulls the handle to the left. What can I adjust to correct this. Boats I have driven in the past did not pull at all.

  4. Barry Simpson says

    Glad to see some results on the SS impeller. What size engine do you run with it. I have a 115/80 Merc on a Wooldridge boat. It’s a great rig.

  5. JR says

    I have a 2008 mercury 90/65, where could I buy a stainless steel impeller? I read the article called enhancing outboard jet performance by Chris Gorsuch, he had good thoughts on how to get more out of the jet and how to set it up properly, but he wrote that a dozen years ago. I called my local dealer and he says there are no other impellers available for my motor.

  6. says

    Saw this in Salmon Trout Steelheader quite a while ago. Glad I was able to find it on your site. Easy to understand tips on getting the jet to run top notch. Thanks.

  7. Bruce Jentink says

    JD, never mind on the reverse gate question, I was looking at the exaust tube, like I said, I’m new to this.
    I did the other things recomended, looking forward to trying it out.
    Bruce

  8. Bruce Jentink says

    JD, Thanks for the tips, I just bought a Alumacraft 16′ AW Jon boat with a 60/45 hp. merc jet, we are going thru the jet for the first time and I notice the reverse gate when in full forward position is a hair smaller at the leading edge than the output tube, does it do any good to polish and remove a little aluminum to fit it closer to the output tube size? And what about polishing it on the inside, the casting looks rough. Any performance gains here???
    Thanks again
    Bruce

  9. Kevin says

    And how about those funky intake fins you can put on the foot, do those really improve the handling and the speed of the boat ?

    • Patrick V. says

      Yes, they do help. 1. Better turning response–they act as rudders. They assist in funneling more water into the shoe, and minimize cavitation.

  10. James Hinton says

    I’ve got a question for you, What do you think about stainless steel impeller vs. the standard aluminum one ? And how about those funky intake fins you can put on the foot, do those really improve the handling and the speed of the boat ?

    • says

      Hey James,

      Funny thing…I just took my 3-blade aluminum impeller off a few days ago and put my old stainless 4 blader back on. I had tried the alum to see if it, being lighter, would give me a better hole shot. Nope…the stainless out-performs the alum hands down. My sled jumps outta the water now, turns lower RPMs and has a better top end.

Trackbacks

Leave a Reply