Jet Jon

[Puddlejumper70]

Hello everyone.
I am building a 11ft jet jon boat using an old abused 91 Seadoo sp.
The ski was junk but had plenty of potential to be resurected in a way that it will still have a long useful life ahead of it.
I have been lurking in the background for awhile searching and learning all that i need to make this project work out..i am at the final stages of assembly and starting to button up all the tiny pain in the ass details..lol..
I am now to the point that i need to explain my build so that i can get some questions answered
make,model of ski-------1991 Seadoo sp with a 587 yellow Rotax 2 stroke engine
boat------------------------------1981 Sears Gamefisher flat bottom fishing boat originally rated at 5hp outboard
these two toys have been melded together to make a nice little skinny water runabout..
I have done the oil pump elimination for the reason that the oil tank could not be mounted high enough to allow good gravity feed circulation,I have made a small oil loop in the engine compartment that holds 5oz synthetic 2stroke oil for the crank and rotary valve needs.that i will of course keep a close eye on too keep fresh and full.
My biggest question now is what TYPE OIL for premix fuel, and oil mix RATIO..this is going to be run in fresh water only,in mostly slow moving shallow rivers and large streams in the western/central PA areas.
I want to make sure i don't cook my engine that i have done so much work on to build this little fun machine.
Once again looking for proper type oil and mix ratios.
thank you in advance for any advice.
here are some pics.

 

[Arriva2001]

You need the API-TC rated oil for the SeaDoo motor, it is not the same as the TC-W3 outboard motor oil. But I have so many questions for you! That looks like a cool project. How are you going to steer it, and control throttle, etc? Are you planning to be able to take it up to full throttle? I think generally the oil/gas needs to be richer for higher revs. If this is going to be going slow, then it doesn't need the full 40:1 ratio.

 

[JeremyD615]

You do need the API-TC oil, but it does not have to be synthetic. The XPS Carb 2T is the correct factory oil. Amsoil and Mystik also have oils that have the correct ratings... I’d mix at 40:1 to start and adjust from there if needed.

 

[Ckrawiec]

That looks dangerous......LOVE it !. Dr. Frankenstein at his finest hour......I'd be afraid to really rev her up though...mwahahahahaha.

 

[Puddlejumper70]

thanks for the replies and comments,and info much appreciated
here are a couple more pics and the steering and reverse gate controls,these are just temp mounts i have to make a trip to the hardware store for some special stainless hardware.
the tall lever is for steering and the short is the reverse gate,hope to have the throttle figured out soon..hope to begin first water tests very soon!!

 

[Arriva2001]

that's super cool that you were able to incorporate that vintage evinrude gear shifter! I'd love to see a video of this thing during a water test. I would think your setup weighs pretty close to the same as a Sea Doo...but obviously the handling is going to be very different. But that's a great idea for using a flat bottom boat like this in a somewhat shallow water situation.

 

[etemplet]

Very cool !! I have an old Gamefisher myself but I'm too lazy.