# My jet Jon build thread



## Boz Mon (Nov 9, 2015)

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 (Nov 9, 2015)

Just some updates from tonight's festivities


----------



## CedarRiverScooter (Nov 9, 2015)

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 (Nov 9, 2015)

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 (Nov 9, 2015)

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 (Nov 10, 2015)

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 (Nov 10, 2015)

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 (Nov 10, 2015)

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 (Nov 10, 2015)

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 (Nov 11, 2015)

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


----------



## CedarRiverScooter (Nov 11, 2015)

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


----------



## Boz Mon (Nov 11, 2015)

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


----------



## TexasLoneStar56 (Nov 11, 2015)

Boz Mon said:


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



=D> =D> =D>


----------



## amk (Nov 12, 2015)

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 (Nov 12, 2015)

These threads are awesome!


----------



## Boz Mon (Nov 12, 2015)

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 (Nov 15, 2015)

Just some update pics from today







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






















Sent from my iPhone using Tapatalk


----------



## Boz Mon (Nov 25, 2015)

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

















Sent from my iPhone using Tapatalk


----------



## PSG-1 (Dec 3, 2015)

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 (Dec 3, 2015)

PSG-1 said:


> 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. 


Sent from my iPhone using Tapatalk


----------



## PSG-1 (Dec 3, 2015)

If you line the inside of that engine cowling with flame retardant soundproof foam, it will make a world of difference. There's an egg crate foam available from mcmaster-carr, very light weight, and very effective at reducing noise under the cowling. 

This is how I have my boat set up, and to give you an idea of how quiet it is, when it's approaching, you cannot hear it, until it's about 100 ft away. Once I've gone past, the sound disappears once I'm about 500 ft away. That's very quiet, considering the average outboard motor traveling at speed can be heard at roughly 1/2 a mile.


----------



## Boz Mon (Dec 9, 2015)

Laid some epoxy resin tonight. Progress


Sent from my iPhone using Tapatalk


----------



## Boz Mon (Dec 12, 2015)

Just a few more pics

















Sent from my iPhone using Tapatalk


----------



## Boz Mon (Dec 13, 2015)

Pump test fit. 






All of the resin work is done as of today. What do I paint the bottom with?


Sent from my iPhone using Tapatalk


----------



## CedarRiverScooter (Dec 13, 2015)

Working through that rear bench must have been hard!

Looks very strong & stiff.

I got some jon boat paint (I think Krylon brand) at Wally's & it matched pretty close. Seemed to hold up well. Was under $5.


----------



## Boz Mon (Dec 13, 2015)

It was actually really easy to cut the seat out. I didn't want to remove it completely because of strength. Need to figure out seating and steering next


Sent from my iPhone using Tapatalk


----------



## CedarRiverScooter (Dec 13, 2015)

I made mockup seat & controls, but still had to move them around some after hard building.

Ergonomics is really important when your running it for a hour at a time.


----------



## SC Designs (Dec 14, 2015)

Looking good Man, Just throw some Rhino Liner on that Bad Boy and call it a day. :lol:


----------



## Ranchero50 (Dec 15, 2015)

Looks good so far. Now comes the fun part of making everything work and play nice with each other.


----------



## Boz Mon (Jan 10, 2016)

Got the bottom buttoned up today so far. I will be dropping in the motor and electronics soon. 







Sent from my iPhone using Tapatalk


----------



## Boz Mon (Jan 10, 2016)

Got the motor mounted too. 







Sent from my iPhone using Tapatalk


----------



## amk (Jan 11, 2016)

Looks great. Rebuild carb if you haven't already. Rhino line for sure I didn't on a little one I built like that and in hind sight i absolutely would have. The 650 may have you thinking about going bigger but that 650 is a good motor I'd run it until the crank goes out then get another motor 650,701,760 they'll fit right in with only slight changes. Also if its already been discussed my bad but get a ss impeller I broke the aluminum in about 2 hours of riding shallow. The rocks knocked the blades off once I put a ss on I ran it for over a year with only the leading edge getting a little dinged.


----------



## CedarRiverScooter (Jan 11, 2016)

Great job tying into the cross braces. Should be stout!


----------



## Boz Mon (Jan 11, 2016)

I'm not sure what this is gonna be like in the water yet. The engine sits kinda far forward so seating will be a challenge. 


Sent from my iPhone using Tapatalk


----------



## amk (Jan 11, 2016)

Itll be fine just have to straddle it with your feet. Are you going to leave that oil hole off the stator cover open or cover it?


----------



## CedarRiverScooter (Jan 11, 2016)

amk said:


> Itll be fine just have to straddle it with your feet. Are you going to leave that oil hole off the stator cover open or cover it?



+1

A high seating position helps you see into the water for rocks & shallows.

Maybe just use the seat for the donor ski.


----------



## Boz Mon (Jan 11, 2016)

amk said:


> Itll be fine just have to straddle it with your feet. Are you going to leave that oil hole off the stator cover open or cover it?



That's not an oil hole. It's where the oil pump was mounted. I'll make a block off plate to cover it. 

I'm thinking box off the engine and sit on the front of that. I need to mock up some stuff to see how it all fits together though. 


Sent from my iPhone using Tapatalk


----------



## amk (Jan 12, 2016)

Lol that's what I meant I've had four of them and removed every oiler from everyone. Maybe it's because I live closer to the salt air but if you leave it open too long you'll start to get rust on your flywheel.


----------



## Boz Mon (Jan 12, 2016)

Yea. I've seen people think that they need to put oil in the flywheel area. That makes a pretty good mess. This isn't my first rodeo though. Here's my usual ride during the summer:







Sent from my iPhone using Tapatalk


----------



## SC Designs (Jan 12, 2016)

I sit behind and straddle my engine with my legs, people always ask me about it getting hot, it only gets warm.


----------



## PSG-1 (Jan 13, 2016)

I would advise against putting oil in the cap for the stator. There are electrical components in there. If you have a stator and flywheel assembly disassembled, it won't hurt to spray a light coat of sea foam or other protective coating on the components. But anything more than that may cause problems.


----------



## Boz Mon (Jan 13, 2016)

I'm not putting oil in there. It's a idea. 


Sent from my iPhone using Tapatalk


----------



## Boz Mon (Jan 24, 2016)

Mounted some angle iron today to hold the deck on. Ran out of angle iron. 


















Sent from my iPhone using Tapatalk


----------



## CedarRiverScooter (Jan 24, 2016)

Looks stout!


----------



## AllOutdoors (Jan 24, 2016)

Looks good!


----------



## Boz Mon (Feb 8, 2016)

Minor updates


Sent from my iPhone using Tapatalk


----------



## Boz Mon (Feb 18, 2016)

I got my seat the other day. I plan on doing some carpet work and finishing up some other odds and ends this weekend 


Sent from my iPhone using Tapatalk


----------



## Boz Mon (Feb 21, 2016)

Some glasswork from tonight. After the scoop dries, it will get a final coat, then the whole top deck will get carpet. 


Sent from my iPhone using Tapatalk


----------



## Redhunter (Mar 3, 2016)

Man, that's looking good. I just started one myself, so I'm researching and learning. I'm planning on doing a weld in style, but you've got me rethinking it the way this is coming along.


----------



## Boz Mon (Mar 3, 2016)

Just a few pics of some bling 


Sent from my iPhone using Tapatalk


----------



## CedarRiverScooter (Mar 4, 2016)

Hey Boz - Just passing along my experience with the top loader grate you showed. I found out the hard way why the OEM grate has tine spacing less that the spacing between impeller blades. 

I hit a gravel bed & before i could shut down i had rocks stuck between the blades of the impeller. It would still run but not push any water beyond idle. Was a long ride back to ramp!

If you need the scoop function, I recommend welding in more bars to equal the spacing on OEM grate. Also see PSG's latest grate design, is very cool.

Great looking tank. Did you weld it yourself?


----------



## PSG-1 (Mar 4, 2016)

Those top loader grates are OK if you only run on open water, where there is chop (and no debris). On choppy water, they perform as advertised, feeding more water to the pump and minimizing acceleration slip.

But on inland rivers, bays, back creeks, and other shallow areas, or in areas where there is a lot of debris, a top loader grate is a horrible thing to have on a jet boat, because it's a vacuum cleaner, and at some point, will result in a stick or gravel being jammed into the pump. If it's severe enough, it could lock up the impeller and cause the PTO to strip out (as many of them are just threaded into an aluminum coupler)

Several years ago, I had to consider the pros VS. cons of the 2 designs, and I decided a top loader grate wasn't for me. But neither was a standard grate. At first I designed it just like the weedless grate of a Sea Doo jet boat, but then improved it a couple of times, by adding more bars on the grate, and then eventually re-doing it as a stomp grate with 1/4" spacing between the bars. 

Will my boat run wide open in chop, or take a turn at full throttle without cavitating? No. But I've learned where the slip limit is on the RPM's for certain conditions, and adjust throttle accordingly. I may not have the performance in choppy water, but when I go across a shoal, at least my @$$ isn't gnawing bricks, worried about picking up an oyster shell, rock, stick, or other object and damaging the pump.


----------



## Boz Mon (Mar 4, 2016)

Interesting info. I'll have to do some research. 

As far as the tank, it was a custom tank we had siting outside for like 10 years. Cut about 3 or 4 inches out of it, and had a friend weld it back together. 


Sent from my iPhone using Tapatalk


----------



## PSG-1 (Mar 4, 2016)

Yep, I know all about cutting a tank to make it fit the boat. :mrgreen: This is what I had to do with my jet boat's tanks, so they would fit the profile of the gunwale:


----------



## Boz Mon (Mar 6, 2016)

It steers and the gas tank is hooked up. Just a few small things now. Should be on the water next weekend!


Sent from my iPhone using Tapatalk


----------



## Boz Mon (Mar 10, 2016)

Got some loose ends tied up tonight. Final bodywork and carpeting on the front wood piece on Friday. Saturday will be a test run. 


Sent from my iPad using Tapatalk


----------



## Boz Mon (Mar 10, 2016)

Sent from my iPhone using Tapatalk


----------



## Boz Mon (Mar 12, 2016)

IT RUNS! And I drove it!


























It's pretty quick and kinda sketchy. Lots of fun and i can't wait till warm weather to really rip it! Need to hook up my reverse, secure the 2 rear vents, and drill holes for air intake. 

The only small issue is the pump is placed so it's slightly trimmed nose down. 


Sent from my iPhone using Tapatalk


----------



## CedarRiverScooter (Mar 13, 2016)

Looks really well thought out! 

I shimmed my pump to change trim, was a lot of work, just FYI.

Love your brick work BYW.


----------



## Boz Mon (Mar 13, 2016)

My issue is I can't shim the pump. It's one of those 1 piece Yamaha pumps


Sent from my iPad using Tapatalk


----------



## CedarRiverScooter (Mar 13, 2016)

Maybe you can get a trim-nozzle for it, or modify the steering nozzle you have to angle it up a bit.


----------



## Capt1972 (Mar 13, 2016)

Boz Mon said:


> My issue is I can't shim the pump. It's one of those 1 piece Yamaha pumps
> 
> 
> Sent from my iPad using Tapatalk


maybe a little work but I imagine you should be able to "shim" the steering nozzle with a little ingenuity.

.


----------



## Boz Mon (Mar 13, 2016)

I'm currently exploring a few different options. 


Sent from my iPhone using Tapatalk


----------



## Boz Mon (Mar 21, 2016)

I d cut my ride plate yesterday but there was a 10mph wind so I'm not sure if it made a difference. I do know that this boat doesn't like chop. We had like 2 foot rollers from the wind and it was constantly coming unhooked. 

I did find a cove that was like glass and did a gps run. Managed a nice round 30mph


Sent from my iPhone using Tapatalk


----------



## PSG-1 (Mar 21, 2016)

You can probably get an aftermarket +5 degree nozzle, or a +5 degree pump wedge that fits between the stator and the thrust nozzle (like Capt1972 mentioned) This will make a difference.


----------



## Boz Mon (Mar 21, 2016)

I looked all around. No one seems to make a wedge for the 144 yami pump. I should have a complete trim nozzle system by mid week though. 


Sent from my iPad using Tapatalk


----------



## Boz Mon (Mar 29, 2016)

Front crank seal failed on Friday. I will be swapping a 701 top end on the 650 bottom end. I'll be using the sbt cylinder exchange. New gaskets and seals all around. Needless to say it was an expensive weekend. 


Sent from my iPhone using Tapatalk


----------



## CedarRiverScooter (Mar 29, 2016)

Too bad about the failure. Are your carbs & fuel pump healthy? They can melt pistons too.


----------



## Boz Mon (Mar 29, 2016)

Yea the carb is a fresh rebuild. The spring for the front seal actually was stuck to the stator when I took the motor apart 


Sent from my iPhone using Tapatalk


----------



## Boz Mon (Apr 4, 2016)

Just a few minor things getting done while I wait for my motor parts to show up


Sent from my iPhone using Tapatalk


----------



## Capt1972 (Apr 5, 2016)

What did you use for your intake tubes?


----------



## Boz Mon (Apr 5, 2016)

They're just holes. The chrome rings are the trim ring from ceiling sprinklers. 


Sent from my iPhone using Tapatalk


----------



## Capt1972 (Apr 6, 2016)

Boz Mon said:


> They're just holes. The chrome rings are the trim ring from ceiling sprinklers.
> 
> 
> Sent from my iPhone using Tapatalk


Great idea!


----------



## Boz Mon (Apr 12, 2016)

Got this thing back together over the weekend. I ended up finding 701 cases so the motor is now a true 701. Took it out for a bit and even with it running super rich on break in, I can tell a pretty big power difference. I'm not ready to take it far from home yet since the water is still cold and the boat is mostly untested. 


Sent from my iPhone using Tapatalk


----------



## CedarRiverScooter (Apr 13, 2016)

I also am leery of the reliability of my floating contraption.

I (almost) always go upstream, & carry a trolling motor as a backup.

A cellphone & a wife aware of your float plan is a good backup too!


----------



## Boz Mon (Apr 21, 2016)

Little update on the boat. It was running really funny on Saturday. Felt like it was hitting a rev limiter. I did some testing and messing around. Swapped the coil out of my Yamaha stand up ski into the boat and it ran perfect. 

I sent the boat coil to jet ski solutions on Monday to have new wires and boots fitted so hopefully the boat will be back on the water this weekend 


Sent from my iPhone using Tapatalk


----------



## Boz Mon (May 17, 2016)

Small update on the boat. It's been running good for awhile now with the new 701. I had to reinforce the front of the boat because it was caving in from water hitting it. This caused a few holes which I ended up through bolting with 5200. The boat seems to not be leaking much now. 

I also have adjustable trim, and last night I swapped the prop out for a skat 12/17 swirl. 

The boat is super fun and it gets up and goes pretty good. Me and my sister have been exploring backwaters on the river. Gps'd the boat at 33mph with me and her in it. 


Sent from my iPhone using Tapatalk


----------



## CedarRiverScooter (May 17, 2016)

Boz Mon said:


> been exploring backwaters on the river. .



This what Jet Jons are all about!

My engine (polaris 750) is in pcs, awaiting new crank.

Can't wait to skim over some shallows again!

Glad your boat is working good.


----------



## Boz Mon (May 20, 2016)

Skat swir prop is the best mood ever for this boat! It takes off from idle like a freight train and hookup in chop is improved a lot! Anyone who's on the fence about spending a lot of money on an aftermarket prop, do it!


Sent from my iPhone using Tapatalk


----------



## Boz Mon (Jun 26, 2016)

Small update: the boat is slowly ripping itself apart still. I ended up taking the center bench out to reinforce the area from the front of the engine to just after the bench. It's the last part of the boat with no reinforcement and it's bad. The rivets are cracking from stress. When I pulled the boat out of the water there was a solid stream of water pissing out the bottom. 

Hopefully this week the issue will be resolved. Who knew this would be the weak point of my build 


Sent from my iPhone using Tapatalk


----------

