# Turbo Jet Jon!!



## mr_hypno (Sep 13, 2014)

Hey everyone!! I'm a new member and a newbie to the whole jet jon concept and would like any input and help I can get on this project. I'll start with the background info. I have a 1987 1648 semi mod v Lowe big Jon. I overheated the original 1986 merc 45 "tower of power" 4 cly. Motor. Then acquired a 2001 merc 60 from a friend last summer for a decent price. The river we run is average 2 ft deep this year with 8 ft holes every now and again. Bit mainly it's too shallow for a prop boat to run in the good spots. So after getting hung up many times with the 60 I decided last winter I'm going to put a prop tunnel in my boat. A total success and I was happy for a while with it. Then the bottom power head gasket went out in the motor and it apparently started to ingest water in the bottom cyl. This in turn locked up the bottom rod to the crankshaft and destroyed all my hopes and dreams. Long story short I'm parting out the merc and stumbled upon a 2005 Honda aquarax f-12x jet ski. Its a 1200cc 4 stroke efi turbo charged power plant. It puts out 165 hp stock and should be an efficient jet unit for What I'm looking to do with it. I have already gutted the ski and have the powertrain laying on the floor. I know my next step is to start fab In the boat and get everything mounted.I also need to fab up a copy of the water plentum in aluminum. My main concerns are porpasing with the jet and steering/throttle/nuetral controls. Every cable that came with the ski will be too short. Any input from anyone will be greatly appreciated.


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## Ranchero50 (Sep 14, 2014)

Welcome to the club, you've come to the right place for good advice from several guys who have converted hull before. Looks like a fun project and should be very overpowered in a 16' hull. You can check out my built thread for some ideas on how I worked around many issues.

Your cables I would reuse as custom ones are expensive and take a while to get, maybe get creative with the mounting like I did with my steering setup. You'll probably end up with pods and a spoon, battery up front as well to keep the hull glued to the water.

Take a lot of pics and be descriptive to help the next guy out. And remember, we spend a ton of time just sitting in the boat making motor noises before we cut the metal. 8)


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## Novicaine (Sep 14, 2014)

VERY COOL DRIVETRAIN... Looks like a fun project, I'll be following your progress.

I had a 90 hp Sportjet 18' aluminum boat that I rebuilt the intake to be a tunnel intake and I repowered to a 120 hp Sportjet, so I'll chip in with any advice I can give as you go. 

The one piece of advice is to make sure everything on the bottom is bullet-proof (thick)... a rock can trash a lot of delicate fabrication quickly.

Good luck!


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## Dark3 (Sep 14, 2014)

Oh man, this is gonna be cool. The boat should be shit your pants fast if you can keep it light.


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## Dark3 (Sep 14, 2014)

What is the total weight of the drivetrain??


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## mr_hypno (Sep 14, 2014)

[url=https://forum.tinboats.net/viewtopic.php?p=366168#p366168 said:


> Ranchero50 » 14 Sep 2014, 07:10[/url]"]Welcome to the club, you've come to the right place for good advice from several guys who have converted hull before. Looks like a fun project and should be very overpowered in a 16' hull. You can check out my built thread for some ideas on how I worked around many issues.
> 
> Your cables I would reuse as custom ones are expensive and take a while to get, maybe get creative with the mounting like I did with my steering setup. You'll probably end up with pods and a spoon, battery up front as well to keep the hull glued to the water.
> 
> Take a lot of pics and be descriptive to help the next guy out. And remember, we spend a ton of time just sitting in the boat making motor noises before we cut the metal. 8)




Thanks for the input. This spoon you speak of is that the bubble I've seen before the intake grate?


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## mr_hypno (Sep 14, 2014)

[url=https://forum.tinboats.net/viewtopic.php?p=366174#p366174 said:


> Dark3 » 14 Sep 2014, 08:43[/url]"]What is the total weight of the drivetrain??




I haven't weighed it but I'm guessing around 300 lbs maybe a little less. It will be slightly heavier than the 60 merc I had on it. The ski specs said it's 789lbs total. A lot of that weight will be ahead a lot further than the outboard was.


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## mr_hypno (Sep 14, 2014)

[url=https://forum.tinboats.net/viewtopic.php?p=366173#p366173 said:


> Dark3 » 14 Sep 2014, 08:39[/url]"]Oh man, this is gonna be cool. The boat should be s**t your pants fast if you can keep it light.




The jet ski did 60 with a not so pretty impeller and pump housing. I'm hoping for about 50 in the boat!!


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## mr_hypno (Sep 14, 2014)

[url=https://forum.tinboats.net/viewtopic.php?p=366172#p366172 said:


> Novicaine » 14 Sep 2014, 08:33[/url]"]VERY COOL DRIVETRAIN... Looks like a fun project, I'll be following your progress.
> 
> I had a 90 hp Sportjet 18' aluminum boat that I rebuilt the intake to be a tunnel intake and I repowered to a 120 hp Sportjet, so I'll chip in with any advice I can give as you go.
> 
> ...




That's the good thing about the Big Sioux River...it's a sand and mud bottom river. Occasional rocks but nothing that can't be avoided.


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## mr_hypno (Sep 14, 2014)

Only pics I have of the boat on my new phone. I will be updating with more later.


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## Chewie (Sep 14, 2014)

I can't wait to see this build, it should fly!! Wish I could help, I love doing that kinda shit!!


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## PSG-1 (Sep 15, 2014)

Awesome! You're at the right place for advice on how to build a jet john, as there are several of us who have built them. Be sure to post pics of your progress, or some video to youtube.

And feel free to check the link at the bottom of this post, (my jet boat build), for various ideas or modifications for your build, such as how to build a stomp grate for clearing weeds from your intake, for one example.

Good luck with it! 8)


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## JJ36 (Sep 15, 2014)

Looks like a rocket. I've got a line on a Polaris 1200 I wanna put in a 1648 this winter. I'm excited to see how yours turns out. Good luck.


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## fishbum (Sep 17, 2014)

Looking good! Should be fun! 
Know a guy with a 1860 g3. With Yamaha
180 hp four stroke. Does 48 mph.


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## mr_hypno (Sep 22, 2014)

Just tossing around the idea of leaving my tunnel in the boat and putting the jet intake on the tunnel. I know this will make me have to mount the engine higher in the boat and jet pump higher on the transom. Any thoughts on this idea guys. I know the advantage will be sucking up less rocks and sand in extreme shallow. Disadvantage will be a loss of speed as it already lost me 7 mph. Thoughts guys??


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## tonka329 (Oct 12, 2014)

I can't wait to find a boat to do my build. I was hoping for someone to do an Aquatrax build in a Jet Jon! I'll be patiently waiting the results. Oh, and take lots-o-pics!  I've wanted a 4 stroke build for my Jet Jon also. Not too fond of 2 strokes with fouling plugs...


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## PSG-1 (Oct 12, 2014)

tonka329 said:


> I can't wait to find a boat to do my build. I was hoping for someone to do an Aquatrax build in a Jet Jon! I'll be patiently waiting the results. Oh, and take lots-o-pics!  I've wanted a 4 stroke build for my Jet Jon also. Not too fond of 2 strokes with fouling plugs...




My boat has a 4 stroke Yamaha FXHO engine. Very efficient on fuel, extremely quiet, and more than enough power to get on plane quickly, even for waterskiing.


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## tonka329 (Oct 13, 2014)

You can pull a Ski, PSG? Your engine is about 160 horse also, right?


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## PSG-1 (Oct 13, 2014)

tonka329 said:


> You can pull a Ski, PSG? Your engine is about 160 horse also, right?




It will pull a ski, wakeboard, or hydroslide, no problem at all yanking me up on plane. Yes, it's 160 HP at 10,000 RPM's

 https://www.youtube.com/watch?v=Ip7RyutVl1s


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## tonka329 (Oct 14, 2014)

Very nice!!


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## airbornemike (Oct 14, 2014)

Bad ass, I need a second boat :twisted:


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## Ranchero50 (Oct 14, 2014)

mr_hypno said:


> Just tossing around the idea of leaving my tunnel in the boat and putting the jet intake on the tunnel. I know this will make me have to mount the engine higher in the boat and jet pump higher on the transom. Any thoughts on this idea guys. I know the advantage will be sucking up less rocks and sand in extreme shallow. Disadvantage will be a loss of speed as it already lost me 7 mph. Thoughts guys??




The longer the pump inlet, the harder it is to draw water. I'd remove the tunnel and mount the pump as low as possible inline with the bottom of the hull. Oh yeah, the spoon is the bubble looking thing on mine. It works wonders to help curve the water up into the pump inlet while pushing the air to the sides of the inlet.


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## mr_hypno (Nov 3, 2014)

Ranchero50 said:


> mr_hypno said:
> 
> 
> > Just tossing around the idea of leaving my tunnel in the boat and putting the jet intake on the tunnel. I know this will make me have to mount the engine higher in the boat and jet pump higher on the transom. Any thoughts on this idea guys. I know the advantage will be sucking up less rocks and sand in extreme shallow. Disadvantage will be a loss of speed as it already lost me 7 mph. Thoughts guys??
> ...





Thanks for your input. I was only going to keep a couple inches of tunnel depth just to keep my intake from sucking up debris so easily. I have already made some initial cuts in the tunnel for what I was thinking. I do have some pics and will post them later and see what you think.


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## Ranchero50 (Nov 6, 2014)

I'd get rid of all of it and ad a decent shallow spoon onto the front of the inlet. At the speeds you'll be running you not have problems picking up trash but you will have troubles with air ingestion. Only about the last 5' of my hull are in the water at 45+, the pump inlet is @ 3' from the original transom. The spoon helps keep the pump inlet drawing water vs. chunks of air. When I go over weed clumps at speed the hull is going too fast for any trash to draw into the pump. At low speeds I've had troubles but not at WOT.

Oh yeah, for your cables, just move your driving station to where they will work. I had to run a shaft to the bottom of the hull for my steering but the throttle cable was long enough to reuse.


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## mr_hypno (Nov 7, 2014)

I personally think its going to work with of course some tweaking and tuning. What inspires me is SJX jet boats. They have a inboard jet tunnel and it must work or they wouldn't build it. Im sure it took a lot of development to make it work. Im willing to spend the time and make mine work as well. The benefits outweigh the downfalls for my situation.


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## gotasquirt (Nov 10, 2014)

I am jealous you have a Honda power plant the way that I set my jet units up is I set the intake as far back as possible if the hull has a small v at the transom put a pad in the hull about 4 foot long start at the keel level and make it just wide enough at the transom for the pump to sit flat no need for a spoon you might want to take a look at the nz jetboating forums I have built 5 jet jons from a 701 Yamaha powered to a 250 hp Kawasaki super charged boat if you want you can email me with questions will


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## mr_hypno (May 2, 2015)

Sorry guys!! I havent been updating on here like I should. Progress has been made in baby steps though. I downsized my tunnel to 1 1/2" tall. Got a start on my jet intake. What a tedious and time consuming part to build!! I didnt do jack squat over the winter on it...negative 20 degrees will make a guy hibernate!!! But im back on task now again and slowly working away at it. Update pics to come.


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## mr_hypno (May 23, 2015)

The calm b4 the cutting storm!!


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## mr_hypno (May 23, 2015)

More looking and thinking :wink:


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## mr_hypno (May 23, 2015)

old prop tunnel


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## PSG-1 (May 24, 2015)

mr_hypno said:


> More looking and thinking :wink:



Building a jet john, you will have a lot of these moments. One thing I learned on my boat, is that it's better to 'ride by and look at it' twice, and only have to do it once!


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## Ranchero50 (May 25, 2015)

Ditto, 90% thought, 9% scrounging for parts and 1% action.


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## PSG-1 (May 27, 2015)

Ranchero50 said:


> Ditto, 90% thought, 9% scrounging for parts and 1% action.




Mine was more like 75% thought, 10% waiting on ordered parts to arrive, 14% _modifying parts that didn't work_, and 1% action. :mrgreen:


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## CedarRiverScooter (May 27, 2015)

My allotment included many test trips on the river, actually the fun part. Improvements are still happening!


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## mr_hypno (May 30, 2015)

This was my original plans for keeping the tunnel. Everything above the sharpie line must go. From the back u can see it wasnt a very even cut lol :roll:. I forgot how my tunnel wasnt bent exactly straight. And the idea evolved from there.


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## mr_hypno (May 30, 2015)

I decided that the engine was going to be way too high so again i cut more of the tunnel out. Ever evolving design!!


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## brianb2247 (Jun 2, 2015)

Keep it up when I was building mine id lay parts in for ideas, are you making yo jet pump aluminum or are you glassing it in


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## CedarRiverScooter (Jun 3, 2015)

I used cardboard, foamboard & duct tape to mock up the layout. This worked well particularly for ergonomics of controls & seating.


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## mr_hypno (Jun 3, 2015)

Jet intake will be all aluminum. Difficult to build but also easy to transfer into a different boat. This is more like a test platform before I buy a brand new 1752.


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## Ranchero50 (Jun 3, 2015)

I wouldn't sweat the transfer. Once you build one, you'll have the skills to modify the setup for another hull.

One word of advice, keep the inlet as close to the transom as possible. Less chance to induce air. Less chance for cavitation in the tunnel. Easier to clean.


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## mr_hypno (Jun 3, 2015)

The way I have the engine sitting in there the intake won't even start till after the transom. The jet pump is going to stick out about 2.5 feet from the transom. It can be heavily braced so it doesn't get damaged when I hit stuff. Which I know I will.


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## mr_hypno (Jun 6, 2015)

Now I decided to cut the tunnel all the way out besides the very back section. Now the engine is as low as it will ever be.


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## mr_hypno (Jun 6, 2015)

Now the tunnel is gone and its back to a reguar flat bottom. I know the welds arent the prettiest but i had some hellacious gaps to fill!!!And I ground them all smooth.


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## mr_hypno (Jun 6, 2015)

Now its time to test fit the Honda. By the end of the night i removed more useless exhaust and save a bunch more room in the boat. Now ill have just as much room as I had with the outboard. Turn around fishing is a must for river fishing!!!


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## mr_hypno (Jun 6, 2015)

My least favorite part...making the jet intake. Its a work in progress. I started out making this then decided the engine needs to be mounted 1st so I can line the pump up with the output shaft.


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## silverbullet2003 (Jun 6, 2015)

Looking good man. What is that sweet shiny rig in the background?


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## mr_hypno (Jun 6, 2015)

silverbullet2003 said:


> Looking good man. What is that sweet shiny rig in the background?




Everyone meet my brother Daren here AKA DERV. Hes the one in the background in most the photos...Holding a Bud Light. :beer: Thats his "Shiny" project in the background. He will be starting his own topic on that sometime in the future! Dont hijack my topic BRO!!!


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## silverbullet2003 (Sep 2, 2015)

It's been a few months. Let's see some progress pics or some kind of update!!!!!!!!!!!


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## mr_hypno (Sep 2, 2015)

2018 bro!!


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## silverbullet2003 (Sep 2, 2015)

Come on man. Baby steps count!


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