My jet Jon build thread

[Boz Mon]

I've been wanting to make one of these for some time now and last night I took the first step. My buddy gave me a Yamaha vxr650. Took it down to a bare hull last night and tonight we are going to cut it up.

I don't have a boat yet but I'm looking at a 16 footer this week and hopefully buying it. I'm not sure how the 650 will perform in that big of a hull, but if need be, I can swap a 701 top end on the 650.

I'll try to add pics periodically and update the thread. I'm super excited to finish this an let it rip!

 

[Boz Mon]

Just some updates from tonight's festivities

 

[CedarRiverScooter]

You're off to a great start!

The 650 should get you about 25 MPH, which is plenty fast for a boat going in 4 inches of water.

I saw your question about pump tunnel mounting in the other thread.

Just relating my experience . . . I had mounted the tunnel with 'ride plate' 2 inches below the jon hull. The jet ski tunnel then sloped up so that it was flush about 4.5 foot forward of the transom.

The design had major problems with sucking in air from wave chop.

Now I have just taken the whole enchilada apart, the only silver lining is that I got to see how strong i had built it.

I am going to lower the tunnel insert so that the ride plate is 3 inches below hull & the have tunnel just about level. I will build a spoon shape, from fiberglass, to flare up to the hull in front. This should divert the air away from the pump intake.

So if you haven't cut off the bow flare yet, you might want to consider leaving most of that on & fiberglass on a flange to glue to.

 

[TexasLoneStar56]

This is going to be a fun build to watch! 8)

Check out this thread;
https://forum.tinboats.net/viewtopic.php?f=21&t=38454&p=391092&hilit=Harley+Boat#p391092


Good luck with your build. I'll be watching!

 

[Boz Mon]

I also had a question about Jon boat weight capacities. Most of the boats I'm checking out in Craigslist have a capacity around 435lbs or so. Should I be worried about finding a boat with a higher capacity?


I'm also wondering how I should position the pump? I see some builds where the nozzle sticks out the back and on some it's almost flush with the back of the boat. I assume there are advantages and disadvantages to each?

 

[CedarRiverScooter]

If I were to start from scratch, I would buy a extra wide & deep boat. Preferably with modified V bow. Spending more on the basic hull will be worth it in the long run, because it will perform better & be more rugged.

I had bought a slightly used 1648, looked new. I had to swallow hard when putting the sawzall to it! But now it is just a boat with a big hole in it.

 

[SC Designs]

Yo Boz Mon, here's the skinny from my end. I'm not claiming to be an expert on Jet Jon building being people have been doing this for years now. There are a lot of good builds and there are a lot of builds that didn't pan out. Unless you find a person that has done one with huge success and buy the exact boat and exact ski and follow their exact process then expect every build to be different. Now I researched for months before starting my build. Mainly reading the do's and dont's but I will tell you this, every build has a different outcome. My build I believe was a success due to part research and part being lucky. I have a past from the 90's where I used to race seadoo's in the IJSBA runabout class so I already have a thorough understanding of ski's and pump operations but a lot of that gets thrown out the door when you throw a flat bottom hull in front of a pump. The spoon Idea is the best way to solve a lot of the issues that come up with a flat bottom boat. Jet ski's are mostly V hulls in nature and that allows the air and some debris to be pushed away for the pump inlet, that's not going to happen on a flat bottom surface so you have to improvise. Now I didn't build a spoon for mine and yes I did have some slight cavitation in the chop but it was minor, that's why I chose to put an aftermarket intake grate on mine and it solved the issue. It keeps the pump charged at all times. But hey, it worked for me, it may not work as good for others because of how there over all design ended up. As far as you weight Question, I have a 14/32 shallow, probably the smallest 14' you can get and probably the smallest build with the 80 HP that I have. I will tell you this. I am 180 and I had a 270lb guy in the front seat. Ran all day at a cruising speed between 28 to 30. Not once did the boat feel unstable or sit low in the water. I even stood up and fished off the back. That being said, I think you will be fine on what ever boat you choose to use for your build. Don't let the weight issue bother you. This is just my 2 cents and again I am not claiming to be the expert, just my thoughts from what I have experienced and researched. opcorn:

 

[JL8Jeff]

I had a Boston Whaler Rage with the Yamaha 650 motor and I ended up putting on the Pro-Tec wake up kit which was a different head, exhaust, carb jetting and K&N filter and it ran strong. I also put on the MSD ignition parts for it. It really ran well and was pretty quick so you might be ok with the 650 and some performance parts. I don't know if they still make the wake up kit or if you would need to do the parts separately if you needed the extra power. I found some old pictures of my Rage 650 motor setup.

 

[Boz Mon]

I think they do still make the kit. I have a Yamaha stand up ski with a protec pipe in it. It's a good pipe but expensive. I'll try the 650 and if that's to boggy, the next step is a 701 top end then maybe a pipe. I really need to get a boat first though [emoji41]

 

[Boz Mon]

Bought a boat today. A tracker 14 footer. Now we start cutting

 

[CedarRiverScooter]

Nice looking boat. Have fun, makes a great winter project. Hope you have a heated workspace.

 

[Boz Mon]

Oh yea the garage is heated. I feel like this should go pretty quick once all of the cuts are made.

 

[TexasLoneStar56]

Bought a boat today. A tracker 14 footer. Now we start cutting

=D> =D> =D>

 

[amk]

I had a 650 in my 1648 originally it would hit thirty empty but run 26 loaded and get skinny. Was a very reliable motor I eventually swapped to a 760 and it matches up well. I also built a 1236 with a 650 and it would run 35 so imo that 14 is a perfect size for the 650 you won't win any races but you'll beat whoevers running an outboard on a similar 14'. Also as you mention when you want more you can always go bigger. 701 or even 760.

 

[Jim]

These threads are awesome!

 

[Boz Mon]

Yea I was hoping for low to mid 30's with this setup. I think the ski I took it out of is supposed to hit high 30's. Once I get it dialed in, I would really like to be able to hit 40.

 

[Boz Mon]

Just some update pics from today

Had some cracks by the pump that will need to be fixed.

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[Boz Mon]

Did a little prep work today. Glued the pump section in and put about a million rivets in it. This 3m 5200 is serious ****.

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[PSG-1]

Very nice work! I notice that this tunnel is set up for the exhaust to pass into it. That's a big advantage, as far as knocking down the volume. If you want to tone it down even more, I'd suggest installing rubber skirting that's trimmed to fit around the pump (look on page 10 of my boat build, about halfway down....the pictures explain it better than I can)

 

[Boz Mon]

Very nice work! I notice that this tunnel is set up for the exhaust to pass into it. That's a big advantage, as far as knocking down the volume. If you want to tone it down even more, I'd suggest installing rubber skirting that's trimmed to fit around the pump (look on page 10 of my boat build, about halfway down....the pictures explain it better than I can)

Very cool I'll look into it. I plan on making some sort of cover to go over the engine too.


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