Super Jet Should my 750sx run as strong as a Super jet?

[neller0414]

So I thought my 750 was running pretty good. Just put in a XiR motor that has a higher comp head than my stock (which was blown), R&D timing advance, PJS pipe, Prok arrestor. Not sure the pitch of the prop, but rode with the original owner a few days ago and I believe he said it was a skat trak and he had bought it for more low end (freestyle). I have a Worx ride plate and aftermarket intake grate.

I rode 10 footers on Lake MI on Friday, and it did okay. EVERYONE else had Superjets. Everyone I ride with has superjets it seems. So yesterday I was riding with a few guys, and one had a bone stock 07 superjet. I had ridden my buddy's heavily modded Superjet and it's ridiculous, so I figured why not try a stocker to see how it compares to my 750.

It flat out kicks my 750's @$$. It's way more responsive, pulls out of the hole better, throttle response is better, and just is flat out stronger.

Is there something wrong with my tuning on my 750? Or does Yammy just make THAT much of a better product?

 

[OCD Solutions]

Do a search on yamasaki and you will see a buddies 750 conversion. He had the same complaint as you and dropped in a yamaha 701. I think the kawi pump was holding him back still but the motor was a huge improvement.

 

[madscientist]

with a pipe and the right impeller it will be a lot better than you expect.

 

[neller0414]

i have a pipe and a good impeller....I'll have to figure out what pitch my impeller is

 

[madscientist]

mine pulls hard as a lot of bolt on sj's but mine is in an x2

can't wait to try a lower pitch impeller.

 

[neller0414]

yeah i dont think mine's tuned right to be honest. maybe i need new jets? i thought with the timing advance, pipe, and this XiR motor with the higher comp head that i would be doing pretty good. I bought this thing with a blown motor. The first time I put the new motor in, i had stock pipe, stock airbox, and no timing advance. I literally don't feel a difference with better airflow, pipe, and timing advance. That doesn't seem right to me....either that, or I just don't remember what it ran like without all that stuff, as I did only ride it one time before adding all of that. I used to have an SXi Pro about 5 years ago...it had an R&D head and that was it for mods, and it was very strong but it's hard to remember that long ago and try to compare. i need to ride some other people's 750's to compare.

 

[j0hnny]

see i find that odd... because my 750sx flat out smokes my friends 701 yamaha. and the 800... god that thing scares me. i do prefer the 701 for freestyle but then again it is setup for it. but corner carving and flat out speed in the river i can cut harder and faster than the 701 and i bought mine in late june and the 701 owner lives on a lake and has 5+ years of riding. idk maybe a freak occurance... maybe rider. but god i love the 750 feel. makes me just want a lighter more freestyle oriented hull for it. again maybe im just an odd duck i have now ridden 3 superjets and i really dont appreciate them like most people do.

 

[jetman624]

I have a timing advance and a 650 coffman pipe on my 750 X2 and freakin rips. I also have a ocean pro nozzle, so that helps. Are you running a stock reduction nozzle? Not sure what the stock nozzle is on that ski but you should find one or look to have yours punched out to 82mm.

 

[2010brandingo]

see i find that odd... because my 750sx flat out smokes my friends 701 yamaha. and the 800... god that thing scares me. i do prefer the 701 for freestyle but then again it is setup for it. but corner carving and flat out speed in the river i can cut harder and faster than the 701 and i bought mine in late june and the 701 owner lives on a lake and has 5+ years of riding. idk maybe a freak occurance... maybe rider. but god i love the 750 feel. makes me just want a lighter more freestyle oriented hull for it. again maybe im just an odd duck i have now ridden 3 superjets and i really dont appreciate them like most people do.

x2. not an odd duck.
i have both a 750 and a sj and they each have there ups and downs but i will NEVER!!! get rid of my 750. when its time for cuttin up or haulin a$$ best believe im on the 750.

 

[restosud]

that pjs pipe is holding you back also.

 

[Jayski]

im forever chasing more power with my 750- and really i have got to the end of the road- If im not happy with it once i get the total loss running- im pulling the motor out and putting a yam in it..... My SJ hits way harder on the low and its pritty much a stocka, pipe head and ignition.- If i did it all again i would had yam powered it for sure (Oh yeah its in a x2) my stocka 750sx is a complete slug compared the the SJ, i rode a stocka sj right after i had been riding my stocka 750- im suprised kawasaki sold a single unit!

 

[Octane_114]

yami's have a lower port timing and a larger pump. I'm not going to start with what all i have in my 750based x2, its an all bottom end ski. it took alot of work to over come a sj on bottom but that ski didnt have near the work done to it as my x2. i was pissed when i took it for a spin and felt the power, with just bolt ons. i can cut a faster lap but for fresestyle yami is going to win unless you go big bore. BUT you should be getting some nice power out of you xir, that is a good motor it makes nice power. kawasaki's i think are a heavier ski too, take chop better. need to start with the basics, that timing advance should have woke that motor. sounds like you have some tuning to do.

 

[Big Kahuna]

The XiR was set up as an out of the box race runabout. Your porting and everything about that motor is designed for more mid to top power. you would be better off finding a std cylinder off a 750sx and throwing that on there. Plus finding out what prop you are running. A stock SXR prop would work pretty good for you.