Its an X2,ITS a Seadoo,no its both

[WFO Speedracer]

So I don't have to post it all again here you go.:sneaky:

http://www.pwctoday.com/showthread.php?t=153892

[special fx]

Cool

[Vumad]

What are the advantages of running a seadoo set up opposed to putting in a yamaha or tweeking a kawi engine? Was this a project based on performance gains or on parts availibility and fun?

[crab]

100 hp

[Big Kahuna]

nice going!!!!!!!!!!

[WFO Speedracer]

Thanks its ridiculous for something to rip this hard considering the the amount I have invested into it.:eek2:

[marz831]

Nice...720's make great power even in stock form. That thing must be insane.

[Vumad]

I don't know anything about the seadoo engines. What makes the seadoo 720 put out more than a kawi 750? What are the 750's doing... 80hp? Anyway, cool project.

[cattledog]

have u had it it in the water yet

[WFO Speedracer]

I don't know anything about the seadoo engines. What makes the seadoo 720 put out more than a kawi 750? What are the 750's doing... 80hp? Anyway, cool project.


Ok class is now in session,,,
The Seadoo engine is a rotary valve induction engine,these type engines produce more hp per cubic centimeter than any other type of two stroke engine,it is because of the rotary valve feature which provides a positive precisely timed opening and closing of the intake port.That means no back flow through the intake to disturb the incoming fuel air charge,it also means easily adjustable timing of the intake timing by changing or retiming the rotary valve itself.There are millions of the 717 engines in use it is the most reliable engine ever produced by Rotax for use in a watercraft.Stock hp is 85 hp,thats with a very restrictive intake system and exhaust,40mm carb and only 150 lbs compression.What we have here is a 46mm mikuni carb,free flowing intake system,very free exhaust and 180 lbs compression.I also took off the heavy pto and replaced it with a Kawi coupler machined to fit the Seadoo crankshaft.The Kawi big pin does put out 80 hp in a ZXI or STS,I don't think any other 750's do actually have 80 hp.The bottom line here is this ,if the whole engine pukes for about $600.00 I can have all new internals and be back up and running,I personally have never been able to break a 717 engine,this one may be the first.There are also several mods such as dual carbs,total loss ignition and larger rotary valve that I can do to this engine that will make it even faster and not affect reliability.As it is it is damn fast and should be very reliable.I went out of my way to make it easily servicable if a problem arises.The fuel tank comes out easily,as does the starter,carb, exhaust system and top end,electrical components are easily acessable in the electrical box where the battery used to reside.The only problem I did have was the starter, that was solved by drilling out the bottom hole in the front cover and installing a helicoil in the starter hole so the bolt could be acessed from the front,now the starter comes out in less than 5 minutes as can be the carb,entire engine can be out in less than 10 minutes.

[Big Kahuna]

yup, what he said............... Just dont port them!!!!!!!!!!!!!!!!!

one thing about Seadoo, they give you a motor that is putting out alot of power whereas Kawi and Yamaha are more reserved on the power output..........

[WFO Speedracer]

The thing I liked most about it is that it just rips ,from dead stop to wide open the power delivery is linear with no dead spots,it doesn't have to wake up or get on the pipe its just there when you punch it,It is extremely rideable,I think this is why a lot of people are now going to the 66e engines in their superjets ,to get that kind of useable hp and rideability.Big engine, small chassis combos have been a mainstay in American tradition since the Shelby Cobra ,Ford Thunderbird and Chevy Corvette.

[crab]

Is that the biggest cc in that configuration?

[WFO Speedracer]

Is that the biggest cc in that configuration?


Yes but it can be bored up to 2mm o/s making it 754ccs,that may in my next bag o tricks,also looking into a total loss syatem now.:eek2:

[Vumad]

Those are really good reasons. Sounds great. Is that the same engine that is in the '96 seadoo XP? (the one with the shock seat) My buddy has that and I recall it being a 727. That ski of his has insane power compared to my other friends XL760.

[WFO Speedracer]

Those are really good reasons. Sounds great. Is that the same engine that is in the '96 seadoo XP? (the one with the shock seat) My buddy has that and I recall it being a 727. That ski of his has insane power compared to my other friends XL760.


No thats the 787 110 hp engine also a good engine but alas it won't fit in an X2 I tried it.:ugh2:

[WFO Speedracer]

Okay I ran it today and it turned 7900 rpm on the trailer,not sure what that equates too while being ridden,I will probably wire up a Seadoo tach and take it for a spin just to be sure,My target rpm is 7000 rpm, max rpm is 7400.:woot::woot::woot::woot:

[WFO Speedracer]

I have had plenty of time to screw with this since I am on vacation from the other site so today I cut out the under seat box for a larger sealed battery to fit into,removed some soaked foam in there,put a 180 main jet in the carb,installed my new handlebar pad,installed some fuel clunks on my pickup lines,hooked up a tach which for some unknown reason will not work and reworked my throttle cable bracket for a straighter run on the throttle cable,I was able to use the same throttle cable bracket but I flipped it over and put a custom bend in it.With any luck it will go back into the water tomorrow for some more ride time.If all else fails I will use my ETACH and get a reading under load while I ride it(scary thought) so I can get the rpms dialed in.

[crab]

So, what model and years do you find this motor

[WFO Speedracer]

95XP,96SPX, 95 and up GTI ,96 and up GTS,96 and up JET BOATS,96 and up GS,its been a mainstay in the lineup for years now.

[marz831]

95 XP; 96 SPX; 95-97 HX - These were all the older dual carb versions

The newer GS and GTI came with a single carb version of the same motor, prob around 2000 and newer.

I'm sure I'm missing some, but that's most of them.

[WFO Speedracer]

Yep I don't know how i forgot about the HX,hell I own one,now thats bad.

[bucklee00]

how did this build end up turning out? and did you ever get any videos? i am very interested in the build.

[WFO Speedracer]

how did this build end up turning out? and did you ever get any videos? i am very interested in the build.

Built it ,took it apart and put a 650 engine back in it with the Seadoo pipe. Moved on to bigger and better, working on a flatdeck X2 now with a one piece hood and a built 787 engine in it.

[bucklee00]

that flat deck sounds like a nice build. So for a "bang for the buck" build, power wise, would you put the smaller sea doo (717) motor in another x2? and why did you decide to take the sea doo motor back out?

[bucklee00]

:bump:

[WFO Speedracer]

First off it has clearance problems with the bottom of the ski. mine actually had a hole knocked in the bottom twice, second you cannot run a water box because of the kind of pipe you must use to make it fit in the hull, it makes good power and one day I may go back to it but I doubt it,I have moved on to bigger and better. 110hp stock vs 85hp stock.

[bucklee00]

alright, thanks for the follow up. good luck on the build