JetJon Conversion - SeaDoo SP into 1236 Fisher

[painlesstom]

Walk around video =D> https://www.youtube.com/watch?v=OKnci-xQJBo

 

[PSG-1]

Very nice work!! =D>

If you want to cut down on the sound levels a little more, try installing rubber skirting around the pump tunnel, where the exhaust is contained. Like this:








To show it in better detail, click this, and skip to 4:25 on the video:

https://www.youtube.com/watch?v=Gxxy3S_Fujc

 

[painlesstom]

Thanks. I had read one of your other posts earlier about doing the flaps which I can see how it would create a secondary type of muffler chamber. Between that, and some foam in the engine compartment from McMaster, the sound could be dampened quite a bit I'm sure. I don't think I'll have any problem with the way it is though, remember I've spend the past year and a half in a Mokai, the Jon is almost certainly going to be much quieter. https://www.youtube.com/watch?v=emwxTSetMDw

 

[sams]

Nice job on the conversion. I have been wanting to do one of these for a while and its always great to see threads like this.

I would recomend against using the egg crate foam at all. As someone who quiets boats for a living I consider myself somehwat fo an expert on the subject. With a small gas engine you will get decent reduction from an absorption material such as egg crate foam , however even better foam formulation such as polyethers will break down rather rapidly when they live in a hot, moist area such as an engine room. A foam faced with a thin aluminized vapor barrier facing will provide similiar acoustic performance and last much longer. Using a seam tape similiar to the facing to seal the edges before installing will give you teh cleanest and most long lasting installation.

If you want it really quiet and can tolerate some weight you can use a barrier conmposite. This will be a composite of 2 layers of foam with a barrier (usually mass loaded vinyl) in the middle. This material is manufactured by a number of companies and I belive that McMaster has such a product in their catalog.

The vinyl skirt around the exhaust is certainly a good idea. You could get into different muffler options as well, however, this is probably space and time prohibitive.

sam

 

[TxTightLiner]

Sounds good!
Thanks for the info.
The guy I got my 1436 camoed it simailr to how you did.
I want to paint my outboard to match it, ill give it a shot once the rain clears up.

 

[PSG-1]

I would recomend against using the egg crate foam at all. As someone who quiets boats for a living I consider myself somehwat fo an expert on the subject. With a small gas engine you will get decent reduction from an absorption material such as egg crate foam , however even better foam formulation such as polyethers will break down rather rapidly when they live in a hot, moist area such as an engine room. A foam faced with a thin aluminized vapor barrier facing will provide similiar acoustic performance and last much longer. Using a seam tape similiar to the facing to seal the edges before installing will give you teh cleanest and most long lasting installation.

I had the aluminized material in the first configuration of my jetboat. In addition to being very heavy when compared to the egg crate foam, it did not have the sound dampening properties of the egg crate foam. I wasn't impressed with it at all, especially the price.

The material I'm currently using boasts a 75% noise reduction rate. Again, this is not the regular egg crate foam like they use on bed mattresses, this material is gray-black in color, and it's made to hold up to some heat. I haven't seen any signs of this material breaking down or crumbling.

 

[painlesstom]

I will post in more detail later, in a rush at the moment. I did get out today finally. Other than some carb issues that kept me from getting as much water time as I'd hoped for, everything worked great. Handled and functioned perfectly, hull didn't mind going 35mph coming down river through my return wake. I'll post more later, here is the video for now. :mrgreen:

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

 

[PSG-1]

Awesome work!! =D> I know that was a good feeling, running the maiden voyage. 8)

 

[painlesstom]

Thanks. It was quite a rush running up the river at 31mph, 35 coming back down. Definitely not the speed I will be cruising at, steering is very sensitive. I had drilled another mounting point on the steering nozzle arm to allow for faster reaction and more travel, I'm going to put the cable back on the stock location since I need LESS steering. This thing will turn on a dime just like a jet ski, without the getting wet part. I was very happy to see nothing leaked and that the hull showed no signs of flex, felt very solid.

When I got home today I pulled the carb off and tore it down. Found lots of trash floating around the jets, and chunks of buildup under the needle seat that were breaking loose. After I got it all cleaned out and put back together, I fired it up and immediately noticed a difference in idle, and throttle response was instant. I've got to take it for registration inspection tomorrow and then work all day, so Sunday will be the next testing session. Will have more to share then. FRANKENJON LIVES!! hahahaha

 

[PSG-1]

Sounds like there was either trash in the fuel tank, or in the carbs, from sitting up for a while. You want to make sure you've got all that mess cleaned out. It can cause a lean condition. A lean condition at WOT equals a hole blown through a piston. I know, because I had it happen with the old 2-stroke Tigershark engine in my boat not once, not twice, not three or four times, but at least 1/2 a dozen times. That kind of thing gets expensive, not to mention very irritating.

 

[painlesstom]

The carb was the source of the trash, I had cleaned the tank, water separator, new fuel lines and filter. The carb was the only thing I hadn't been through since it had run good in the ski. Then it sat with cut lines while I did the build, I'm sure stuff worked it's way in there. It's all clean now so tomorrow should be fun. I went with a Seadoo donor for the availability of parts that aren't very expensive, both OEM and aftermarket. I also like the pump design of the Seadoo over the Yamaha. I can only imagine what you went through with that Tigershark... I couldn't imagine rebuilding a motor 6 times in a row, something would have gotten shot after the 3rd time if it was me! lol I'm guessing that's why you went to the different "High Output" motor. You built a mean boat for sure. 8)

 

[PSG-1]

Yeah, when I think about the money I dumped into rebuilding that POS engine at 1500 dollars a pop (about 4 of the rebuilds were covered under a no-fault warranty), VS. spending 2500 dollars for the FXHO engine, it makes me sick to think about it.

Heck, I should have just went with the FXHO from the start, but then again, I did it the first time on a budget, not wanting to spend a lot of money because I wasn't sure if it would even do what I wanted. But after running it for about 6 years, and rebuilding the POS engine about once every 100 hours, I decided it was time to get a more reliable engine. And I definitely have that, I've taken this boat places I would have been afraid to go with the original engine, for fear of breaking down.

 

[painlesstom]

You'd think the company would have helped figure out why they had to honor that warranty 4 times! Sounds like it worked out for the best though.

I had a blast on the water today, was out for a few hours this time. Other than an annoying off idle hesitation, she ran great. Old gas though, so some fresh will probably make a difference.

Adjusting the steering geometry for a slower ratio helped stabilize things at high speed, 35mph is not a balancing act anymore. Comfortable cruising speed is 25-30. Going to make another steering stick that will let my wrist rest more naturally, right now it gets cramped up during extended runs. Hull still shows no signs of any problems, solid and leak free. Flex during high speed was something I was concerned about from reading others experiences from grafting hulls together, and the simple fact that Jon boats weren't designed to go 35mph. Really glad none of that has been an issue here. Boat is still very stable when going through wakes and choppy water, but it does get out of the water enough to unload the pump as you will hear in the video, luckily it's rare that I'd have to go through stuff like that. River is pretty calm here.

https://www.youtube.com/watch?v=Dd4eheHMCg8

 

[JMichael]

Looks like that is going to be the source of a lot of fun.

 

[PSG-1]

You'd think the company would have helped figure out why they had to honor that warranty 4 times! Sounds like it worked out for the best though.

Well, with the "no-fault" warranty from SBT, they don't ask questions, they rebuild it at no cost, regardless of what caused the failure. And that's for a period of 2 years! I paid twice out of pocket to have the TS900 rebuilt. Then, I took a TS1000 engine out of my girlfriend's jet ski that had blown up, and paid to have it rebuilt, and put it in my boat (I bought her a Yamaha VX110 to replace the TS) So, those 3 rebuilds added up to about 4500 dollars. Again, it makes me sick to think about it.

With the engines in my boat, every time there was a failure, it was a hole through the top of the center piston. And not really knowing much about how to tear down and re-build an engine, I sent it off every time, not realizing I probably could have pulled the head, and just replaced the piston....d-oh! #-o
Sure, that would have cost me a couple hundred dollars in parts, but at least I could have gotten the engine up and running in 1/2 a day, and not have to pull it, strip down to the block, and pay 100 dollars every time to ship it to SBT.

Anyhow, I did figure out the cause of the failure....letting so-called 'mechanics' work on the carbs! When I got brave enough and decided to tear into the carbs on my own, I found the jetting was ALL screwed up, and the center jet was WAY too lean. Oh, that, and the rear spark plug wire being too tight, causing intermittent contact with the coil, causing it to mis-fire throughout the throttle range. No wonder it ran crappy!

I had a blast on the water today, was out for a few hours this time. Other than an annoying off idle hesitation, she ran great. Old gas though, so some fresh will probably make a difference.

If you've been having the same weather we've been having here in SC, you had perfect conditions for boat riding! Almost 80 degrees here Saturday, we beat the old 1949 record. And to think two years ago, it was so cold here, I was running my snowgun almost every night, we had it piled up over 8 feet high in the backyard!

Adjusting the steering geometry for a slower ratio helped stabilize things at high speed, 35mph is not a balancing act anymore.

I'll bet! This is why I went with a 270 degree helm for my steering, instead of a 135 degree. I didn't want it too squirrelly at high speed. But then I didn't have my cable set-back correct where it comes out the transom, and I had it jury-rigged with a bracket welded to the steering bracket, and with that setup, it lacked almost an inch of travel both ways. In other words, it had 1/2 the steering response it should have had. It worked, but not too good in a tight turn. More than one time, I ran into the marshgrass, LOL.
When I redid the boat with the FXHO, I set the cable just right, it only lacks 1/8" on either side. Now she turns fast!

Comfortable cruising speed is 25-30.

Yep, same here, it's about 30 for my boat, right at 7K RPM. With the TS engine, it was about 28 MPH at around 5400 RPM.

Going to make another steering stick that will let my wrist rest more naturally, right now it gets cramped up during extended runs. Hull still shows no signs of any problems, solid and leak free. Flex during high speed was something I was concerned about from reading others experiences from grafting hulls together, and the simple fact that Jon boats weren't designed to go 35mph.
Really glad none of that has been an issue here.

It's all dependent on how well you build the boat and use bracing. Structural components like inner hulls, front and rear decks, engine compartments, etc, help make it more rigid. Without proper structural bracing, the boat will flex like a beer can.

Boat is still very stable when going through wakes and choppy water, but it does get out of the water enough to unload the pump as you will hear in the video, luckily it's rare that I'd have to go through stuff like that. River is pretty calm here.

https://www.youtube.com/watch?v=Dd4eheHMCg8

I watched that video, looks like a fun river to run on. And again, you had nice weather to do it, even in the middle of January!

ANY jet will cavitate when hitting wakes, whether it's a jet ski, jet boat, or a jet jon. Pump, impeller, and hull design can help minimize it, or in some cases, make it worse. It's best to go through waves/wake slowly, to keep the cavitation to a minimum, as it causes a lot of undue vibration, and a sudden unloading of the engine, letting it rev much higher (there is a rev limiter in the CDI to prevent over-revving)

You could also insure better hook-up in light chop by using a Wet Wolf Adjust-a-Thrust pump cone, or even a top loader grate. Only problem with the top loader is that it's more suceptible to fouling, because of its design. I can't run one out here in the marsh, too much grass.

Anyhow, keep us posted! I want to see some video of the jet jon blasting over some shoals. :mrgreen:

 

[painlesstom]

Made some carb adjustments, topped the tank off with fresh fuel, and saw how much fun this boat is going to be. Perfect day too, with partly cloudy skies and 80° temps! Love Georgia... I couldn't be happier with the boat, other than to get it outfitted with rod holders etc.. I plan on doing lots of fishing out of this thing.

I don't have a tach for it yet, but top speed is 36mph so far. I'd like to wire a real tach to the motor, but haven't been able to find much info on how that would be done on the 96' MPEM, would also have to install an ignition switch so there would be a source for 12v switched power. Not sure I want to dig into things that much, might just go with a Tiny Tach later...

The cavitation doesn't bother me since there is a rev limiter, just going to try to keep it to a minimum since it can be hard on the pump. I don't mind going 25mph, doesn't seem to have any issue with it at that speed. On flat water I can fly though!

Also came to the conclusion that my trailer was too high, and the bunks were also too high. Had to back too far down the ramp to load and unload, so I swapped tires with my utility trailer (12" vs 15") which dropped everything 2". Then I took the bunks and laid them flat on their side and bolted them directly to the frame, that dropped the boat roughly 3". So now the boat is a total of 5" closer to the ground than before and shouldn't require backing down the ramp near as much as before. I hate having to put my truck wheels in the water, something wrong with that picture... lol Should pull nicer down the road with the center of gravity lower.

https://www.youtube.com/watch?v=WST3uQHgfB4

 

[PSG-1]

To run a tach, you'll need to find the tach wire (usually green, but it depends on mfg.) and the 'ignition' wire (purple, as per ABYC codes, but again, it may vary with mfg.), as well as pulling a ground.


ANY tach should work with your engine, as it reads the 'tapping' (on/off of 12V+ signal sent by the crankshaft position sensor) You should be able to find a service manual for that engine, and it should show a wiring diagram or color code. If not, you'll have to do it by trial and error.

Best way to do this is to use a multi-meter to find your + and - voltage, and if there is any doubt, use some jumpers with alligator clips, and then use small glass fuses that blow at 1 amp. This way, if you DO make a mistake, you pop a fuse, instead of a component in your CDI.

I ran a teleflex outboard motor tach with my Tigershark engine. But since the FXHO runs up to 10K RPM, I needed a tach that read higher than 7K, so, I got the actual factory tach that goes with the FXHO engine in the AR230 jetboat. And that WAS a trial and error kind of thing to figure out the 8 wires that run to the tach (3 of them are for indicator lights) Not only that, but there are no stud connectors on the FXHO tach like on a regular tach, it uses an 8-pin plug, which, BTW, I was not able to get, I had to make a multi-pin plug (that was a real *****)

So, if I was able to do it with that tachometer, you should be able to do it with your boat!

 

[painlesstom]

Yeah, that's alot of work just to have a tach. When I was younger and in my muscle car days, a tach was the first thing I put on a car.. it was just necessary! LOL Now it's just a handy tool on occasion, but I can easily live without it. Speedometer is what is necessary now, which I have in my GPS, and that tells me plenty about the motor and pump. I'm just very glad that the past couple months of slaving over this boat has paid off, and everything worked out as planned. Now I've got people thinking I can build one for them too, I am not that energetic! .. lol I will say that if I had to to it all over again, I would. Can't say I would change much either, maybe go 14' instead of 12', but I'm very content with how it all worked out in the end.

Now, we just need to figure out how to coordinate a JetJon gathering. :twisted: I often wonder how many boats are out there that have been built, and actually get used on a regular basis. I know there a plenty out there that were thrown together, or half finished, would be really cool to get a bunch of JetJon's together in one place to see all the different ideas that went into them.

 

[bigwave]

A fine job, looks like a very fun ride. I can't wait to see some big ole cats on the deck. I watched the video, my favorite part is the very beginning, you have two boot prints on the deck....now your just missing the fishing poles. =D> =D> :beer: :beer:

 

[fool4fish1226]

That is one cool ride - Great job :beer: