# New memeber, starting jet jon build



## bigskip83 (Mar 8, 2014)

Hello everyone! My name is Reid and am new to the site. I have been surfing the site for some time now and love the builds that are on here! I have been wanting to do a jet jon project for a long time. We finally have the boat and the ski to do it with and will be starting on it soon. The boat is a 16 foot all welded monarch hull and the ski is a 97 Polaris SL 1050. We have the engine running and will be pulling it out of the ski next. We are decent at fabrication and have welded/worked on aluminum boats often. I have seen on the site that some of you have used aluminum intake housings from Yamaha jet skis in your builds. Since I don't have one on hand I was wondering if anyone knew if that intake housing would mate up with the pump from a Polaris? It may be a long shot, but maybe someone has tried it on here. We don't know a lot about jet ski pumps so this may be a broad question? I really like the fact that the housing and the shaft can be cut down to save room in the boat and just in general looks like a easier way to do it rather than fab out the housing from scratch. Thanks in advance and looking forward to sharing the build!


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## PSG-1 (May 1, 2014)

Use a Spartan Jaw coupler from a Yamaha jet ski to connect the pump to the engine. You will need to cut threads on one half of the coupler to match threads on the PTO from the engine. On the other half of the coupler, cut threads to match the pump shaft of the Yamaha pump. Oh, that's right, no threads, they use splines.....you will likely need to cut the shaft shorter, (they are WAY too damn long anyhow, that encourages lateral deflection/vibration) then cut some threads on the shaft, with a shoulder. 

The most important thing is to get your pump-to-engine alignment as close and precise as possible, and when I say precise, I mean, within .020", or you're going to be replacing pump seals, maybe worse. 

Easiest way is to find center on the boat, install the pump FIRST, and then install the engine. However, make sure that however you are installing the pump, you have the correct set-back and angle to allow the engine to line up, including with the mounting system you will use for the engine.


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## bigskip83 (May 1, 2014)

Thanks for the reply PSG-1! What you described is exactly how I was planning on doing it, after much thought and research. I finally had some time yesterday to work on the boat and decided to use the existing parts and pump from the Polaris. Figured why not since they are already there and will bolt up. Plus it will keep the cost down rather than having shafts machined and beating my head against the wall, haha. I did pick up a Yamaha 1100 pump with reverse bucket though. I figure we can work the bugs out on this one and start a new build with the right stuff. I have followed your build and love what you did with the boat! The current boat that I am using is in pretty rough condition. Going to save a few pennies on this build then look for a better suited hull to use the pump in. Thanks for the reply again! ill post some pics once I get going on it.


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## PSG-1 (May 1, 2014)

No problem, glad to help out. My build should give you a pretty good idea how to go about doing yours. 

I will tell you that it is a LOT easier to go ahead and do the pump tunnel FIRST, that way you can turn the boat upside down to do the welding, instead of having to do it overhead like I did. That's a real PITA. 

PM me if you have any questions, and good luck with it. Be sure to post pics of the progress!


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## bnt5 (May 2, 2014)

Not to hijack a thread, but I am in the same "boat" as bigskip, planning on utilizing the Yamaha bolt in intake. Would there be a way to mate the original jetski pump to the different brand aluminum intake, in this case the Yamaha GP760? This would ease the cost of having to create a different shaft and also would allow the builder to utilize the pump that is already in their possession along with trim...reverse bucket etc...

Maybe this is hairbrained but an adapter plate that has the bolt pattern from Yamaha intake and original ski's pump..... :shock:


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## PSG-1 (May 2, 2014)

It would be one helluva undertaking to try to get another manufacturer's pump components to bolt up to a Yamaha pump intake duct.

First component is the wear ring, then the stator, then the thrust nozzle, and finally the steering nozzle. Again, trying to mate a Sea Doo or Polaris wear ring up to a Yamaha duct isn't likely to happen.


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## bigskip83 (May 2, 2014)

bnt5, I tried this also with the Polaris thrust nozzle, no dice. The only way that I have found to make it cost efficient is to use the same parts. I was trying to miss match Polaris and Yamaha pumps and I could just see the dollar signs in machinists eyes, haha. Im going the fiberglass, 5200, bolts and rivets method for the first one to see how it handles on the river here before doing a real detailed build. Not really the way I wanted to do it, but more of a test project now. No rocks on the river here only mud bottom so hopefully it will stay together. If you do find a solution definitely keep us informed


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## bnt5 (May 3, 2014)

I am in the beginning stages of my build, the part where I am rebuilding the jetski engine so I have a running motor...so I haven't gotten into the nuts and bolts of the jetjon yet. If I had it to do all over again I would just use a Yamaha GP800-1100 ski/engine and build off of that platform since everything unbolts and installs into the jon boat. Since that isn't the case I might end up using a fiberglass hull and working from that angle (weight being a real issue). I really want to go the aluminum boat route but getting an entire Yamaha pump assembly is going to be costly and I have a perfectly good one sitting in my garage with power trim and reverse, it would be a shame to toss it. The whole crappy part of this deal is that I cant try to come up with a workable solution of mating the two systems without first purchasing an expensive used Yamaha pump. Kind of a danged if you do and danged if you don't situation.


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## He Reigns (May 3, 2014)

bnt5, I feel your pain, I would rather do a full bolt in on my project, the problem is I have the skills but not the tools to weld aluminum. My only option is a grafting of the PWC hull into the boat. I like to do things the right way the first time and the grafting seems to be....well not the best way to do it. It may be my only option though. Good Luck and keep us posted.


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## bigskip83 (May 6, 2014)

That's exactly how I feel about it also. I have the tools to do the aluminum work and always like to do things the right way. In this case I think it is wise to just use the things that I have on hand and make it work. I'm saving the Yamaha pump for a different application down the road. This boat will be a trial run. I never ran the jet ski besides on the trailer prior to pulling it. It was running ok, idling a little high but don't know if it is a reliable engine. I just know that if I go through the paces of installing a Yamaha pump and a lot of cash towards machining that the engine will sure enough crap out on me on the second run up river, haha. Saving the money on this one for a better suited build with matching parts.


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## PSG-1 (May 6, 2014)

Just in case you really don't want to go the grafting route.....I have a used Yamaha XL1200 pump (complete) that I would be willing to part with for around 500 dollars. To buy all the pump components new would cost over $1000. 

I bought this pump, as well as a Yamaha VX110 jet ski with low hours, in the hopes of building a jet boat for someone, but they backed out, as did a few others when they heard the price. So, between the disappointment of potential builds not happening, and then my bout with anti-nmda encephalitis back in February that really scrambled my ability to concentrate, my memory, and attention span, my jet boat may be the last one I'll ever build. 

By the way, I also have a couple of Solas impellers for the XL1200 pump, I forget what pitch they are, but they are aftermarket performance props.


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## fishbum (May 7, 2014)

I seem to remember you saying that the gp1200 was the model 
to look for with the good intake? Also I don't see anyone talk about using the 1200 motor with that pump? Not a good motor.?


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## PSG-1 (May 7, 2014)

I've never heard anything bad about the XL1200 engines. So, if you could find a complete Yamaha Waverunner that has the bolt-in duct, like the XL1200 or the GP1200, you would have everything you needed to do a build.


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## gotasquirt (May 11, 2014)

just use the Yamaha jetski intake and you can get an impeller to match your motor I am running a yammie pump behind a kawsaki 12f 4 stroke be running it that way for years just my 2c will


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