Need advise on 750 swap

[2strokeforever]

I currently have a 1993 X2 with a 38mm carb, looks like the cylinder might be ported, a westcoast exhaust manifold, and headpipe and kerker pipe. The kerker pipe looks really small and the guy who sold me the ski was a little shady so I am slightly suspicious that the pipe might be off of a smaller engine.

Im looking for more power, I found a good deal on a 96 750 sxi, but I heard they dont have great bottom end.

How will the bottom end compare to my 650?
Right now it struggles to get a 180lb wakeboarder to pop out of the water so I cant afford to loose any bottom end or it wont be able to do it at all.

Ideally I would get a 800sxr motor but in canada those cost way too much.

 

[kevbo]

That 96 sxi was the best original hull 750s. What hurts the low speed thrust its small 76mm nozzles. Kawasaki was trying to make them go as fast as possible for the magazine reviews. A nozzle from a 750sx or ss/xi is 80mm and will provide more thrust. A 650 nozzle is even better except it’s steering arm is shorter. You will need to move the ball at the handlebar plate to reduce its throw. Don’t expect a 750 to be like a superjet, they are shorter, harder to ride, and won’t have as much low speed throttle response or thrust. The kerker 650 pipe was smaller in diameter than others. To answer your question, a stock 96sxi has a little more thrust than an X2.

 

[WFO Speedracer]

Any 750 motor you put in that hull is going to need a really good pipe to get power out of it , with a stock pipe or a KERKER it will only be marginally faster if at all.

 

[fastgtfairlane]

The 650 will have better bottom than the big pin 750s. Post some pictures of your ski and pipe. Otherwise no way of knowing what you've got.
So you're trying to use a x2 to pull a wakeboarder? Seems like there are better options for doing that. A stock x2 can be a struggle just to ride 2 people on it let alone pulling a wake boarder. Having the 650 ported with a good pipe, carb and impeller will as good if not better bottom and midrange than the 750sxi engine and even 800 engine.

 

[WFO Speedracer]

A properly ported 650 with a decent pipe, head and a 44 carb will run circles around a small pin 750 in an X2 if it's set up correctly .

 

[Storbeck]

Sure but if you did all of that to a 750 it would run circles around the 650.

 

[WFO Speedracer]

Sure but if you did all of that to a 750 it would run circles around the 650.

Lots of if's there , if you already have the 650 why not , a pipe that works well on a 650 usually doesn't on a 750 , basically on a 750 you need a B pipe period , go back and read what he already has , to me it looks like he is maybe an exhaust pipe , a head and a carb away from having a really decent running ski.

Or you can start over with a 750 , have it ported , buy a head , a B pipe and a either dual 38 's or a single 44 and relocate the electrical box , in the end you have spent a ton of money , I am not sure it's a wise choice financially for the power gain .

I am sure he can buy a sitdown to tow that wakeboarder with cheaper than he can do a 750 conversion in the manner which you stated though.

 

[2strokeforever]

I was mistaken, its a kerker headpipe, I lengthened the coupler as much as possible to try and help low end and to reduce water flooding the cylinders when balancing with the engine off


Heres a few reasons I think its ported, the main one being the self proclaimed vintage kawasaki expert that sold it to me built it out of his parts pile and didnt notice the pistons hit the head. I fixed it once I figured it out but that must mean the base is shaved. So I guess that means the head is somewhat done since its pretty high compression and the squish is set correctly.
The piston also dosent go all the way down in the exhaust port.


On the lookout for a factory pipe for sure, just need to figure out what the long term plan is before buying the wrong parts.
Would a 750 small pin be the way to go or stick with the 650?

 

[kevbo]

I have been working on X2s again trying to make a high port 750 work with a Superjet B pipe. It was a little different than I remember from 33 years ago. Here is what I have learned. (1) It takes a very flat impeller!!! (2) You will very likely melt the front piston with a single carb!!! I found that OEM duals or a pair of SBN44s both work great and wont let one cyl run hot. A full length coffman 650 pipe came on sooner and pulled the same as the FP superjet limited pipe. Stock head 165psi and stock timing with a 3738 cdi. A low port cyl can pull steeper impellers and have better response. You can use any 750 cyl on any crank/case, just make sure the sleeve clears the crankshaft!!! Raising the exhaust port from 178 to 192 hurts response and shifts the rpm range up so flatter impellers are required.. I know that small pin XI cylinders are 186 and are a lot more forgiving when it comes to finding an impeller that works.. Also X2s like to take on water fast so install an electric bilge pump. After lots of tuning and one burned piston, I ended up with a couple of fast X2s that are completely reliable on pump gas. The one running the Coffmans pipe is a little faster than the other running the SJ B pipe, who would have thought?

 

[WFO Speedracer]

I would put a decent pipe on there and see what's what , that Kerker pipe is barely better than a stocker, a dried out modded stock pipe might even be faster , look for a Coffman or even a Westcoast or the new PJS pipe if you are not planning to swap , if you even think you might engine swap it down the road go for a better exhaust pipe that will work with a 750 motor.

A stock 44 carb of any Yamaha 650-701 and an adaptor plate for the stock manifold is a cheap upgrade that you will not regret , I ran a 38 Kehin on mine for years, when I went to a 44 there was a major difference in power ..

I can't be sure but that doesn't look like a Westcoast exhaust manifold , it looks like a stock manifold that had some goober welding on it to me.