SX/SXi/SXi Pro Can I put a 750 in my 650sx?

T

tx650sx

Location
Austin, TX
I want to build more power and thought about starting fresh with a 750 motor in my 650sx. Before I buy a motor I wanna know if it is even possible? Thanks
 
vitaly

vitaly

Анархия - мать порядка!
Location
NY/NJ
tx650sx said:
I want to build more power and thought about starting fresh with a 750 motor in my 650sx. Before I buy a motor I wanna know if it is even possible? Thanks
Click to expand...
Yes, you can.
Most likely it's not worth it, unless you love the 650 hull.
 
D

ducesrwld

X
Location
antioch,il
i built my old 650 up for my brother who is a twig and likes the 650 hull. put a 750 SS motor in it with 750 electronics, 650 westcoast exhaust, and a 42 mm carb. thing rips pretty good, edges out my stock sxr. i like riding it here and there just to remember the good old days since i rode em for a decade or so. once my Sxi sleeper is put back together i don't plan on riding the old 650/750 much.

diesel
 
S

Stuart

Location
Mountain lakes
Can I put a SS 750 in my 650 SX?

Ok- so I read another thread and I heard if I want to put the motor I have (SS 750) into my 650 sx hull I can but it requires some modifications. With regard to the electronics, I have the electronics coming off the 750 so my question is do I just buy the CDI box ( around $180.00) and bolt it in where my 650 box is? And my second question is with regard to the exhaust. I have a 650 west Coast pipe that I want to use but I only have the 750 exhaust manifold. If I buy a 650 manifold will it bolt right on to my 750 engine? Thanks for any help or any other advice anyone might have...BTW my hull is an 87 and my engine is a 93.
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
Read the X2 forums. Lots of people putting 750 in X2's. A 650sx and a X2 are very similar, but the SX has a larger engine compartment and will probably be more accomidating to the larger 750 pipes. My X2 is an '87 and my motor is a '94 XI SS.

My issue was fitting a 750 pipe in my X2, but the SX has a lot more room in the hull for pipes. If you run an AM 650 pipe, room is definately not an issue. The second biggest problem was figuring out what was necessary with the pump since the 650 pump can't handle the 750 motor unless you change the nozzle and get a modified 750 prop. The 650 pump will work just like you have it right now but your motor will not perform to it's potential w/o modifying the pump.

No, you cannot just bolt the 750 box in where your 650 box is at. The 750 boxes are much larger than the 650 box. The 750 CDI is about the same thinckness but is twice as wide and twice as long as a 650 CDI. The coil is also larger, so even if you take the items out of the 750 box they still take up significantly more space than a 650 electronics. You can run the 650 electronics if you modify the 750 cases. The advantage to this is the 650 flywheel is lighter and improves bottom end. If you have the electronics that came with you SS motor, simply strap the entire box to the fuel tank with the tank straps where the stock oil resivour was. (You can't mix-match, it's complete 750 or complete 650).

A 650 exhaust manifold will bolt right onto a 750 or 650 motor, but the 650 manifold will be a tiny bit restrictive compared to a 750 manifold. In anycase, if you have a 750 manifold, just use that, unless your 750 manifold is the 4-bolt style from the SS ski, then obviously that wont work. You should get the westcoast manifold that matches your pipe and it bolts right on. (btw, b4 u ask, intake manifolds do not interchange.)

The simplest thing to do is drop in the motor, buy the 650 exhaust manifold, bolt on the AM 650 pipe, might line up with your stock exhaust hoses, drill a couple holes in the waterbox baffolds (there's a post here on how big of holes and how to do it). That is enough to get you on the water. After that, bore your pump nozzle out to 85mm (from stock of 83mm) and get a 13/18 750/800 prop and have it cut by impros or someone else to work with the 650 pump. Done.
 
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Midlake Crisis

Midlake Crisis

Site Supporter
Location
Bakersfield, CA
@Vumad, this was a great post. I am really close to doing this on my beloved 650sx, right now I am looking closely at two options:

Buy a 750 Small pin and use my 650sx electronics with Newmiller lightened flywheel
(Requires the case tear down and machining for electronics, but uses all my current sano electrical)

Buy hybrid BP cases w/800 cylinder & head, 800 electronics
(roughly twice the cost, converting electronics, but better port timing, displacement)

I have seen some old threads on how to do the machining for the 650sx flywheel into the 750 cases, and am not feeling very confident that I could do it right by myself.

Also, I have a stock SXi Pro impeller I thought I could have cut back to fit the 650sx pump, or would need an impeller suggestion to go with whatever package I end up with.

Any suggestions?
 
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S

Sb_252

Location
Australia
G'day guys just bought a 650 hull with the 750 conversion already done to it. I can't see where anything has been machined to run the 650 electrics as my ski is still running the 650 stuff. I'm also a little concerned on timimg. there is a mark on the case and the stator plate but realistically could be all wrong being different motor. Has anyone done the conversion with 650 electrics and know if them timing marks are correct? Cheers. And also after trying to work out all the poop someone has done in here just buy a 750 already done. This is a knightmare.
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
Midlake Crisis said:
@Vumad, this was a great post. I am really close to doing this on my beloved 650sx, right now I am looking closely at two options:

Buy a 750 Small pin and use my 650sx electronics with Newmiller lightened flywheel
(Requires the case tear down and machining for electronics, but uses all my current sano electrical)

Buy hybrid BP cases w/800 cylinder & head, 800 electronics
(roughly twice the cost, converting electronics, but better port timing, displacement)

I have seen some old threads on how to do the machining for the 650sx flywheel into the 750 cases, and am not feeling very confident that I could do it right by myself.

Also, I have a stock SXi Pro impeller I thought I could have cut back to fit the 650sx pump, or would need an impeller suggestion to go with whatever package I end up with.

Any suggestions?
Click to expand...

You just need to set your goals for the project. How much modification, how clean the build, and how much money you are going to spend.

I'd run the electronics that come with the motor. I don't see the advantage of the 650 electronics on a 750 motor. If money is not an object to have your cases properly machined, then run a bad-ass ignition with the 750/800 electronics. How much benefit is the 650 flywheel when talking about the weight vs the 800 electronics?

The only advantage of the 650 electronics I can see is a clean, sleeper mount of the electronics box. That is why I say consider your goals in the project.

The motor situation is budget driven and how much you want to invest into a 650sx.

I have a very modified X2 that never gets used. If I did it all over again, I would have stopped way back long ago when I had a 750sp with 1-44sbn and westcoast pipe, done, just ride it. I have a lot more time and parts in it now. My 750bp with FPP, custom waterbox, dual 44s, hooker prop, etc has the potential to hit way way harder than my buddy's X2 with basically my old setup, but if you ask me if its worth all the time and effort... I was happier when mine was like his.

Don't do the ported 800 unless you are willing to go all in with a good pipe and etc and tune it out right. Otherwise I personally do not believe it's worth the money. A 750 sp with a 650 pipe is a good time. Getting everything to properly tune out that 800 and do it cleanly is a major investment.

Best thing I ever did for myself in this sport was buy a superjet and set a rule for bolt ons only. I ride all the time now. I'm not saying buy a superjet. What I am saying is be careful getting invested in complicated customizations.
 
S

Sb_252

Location
Australia
Your spot on I've raced mx my whole life and it's same deal people get caught up spending money on poop that isn't worth it. I gonna get this thing running correctly and move it on and buy a stock superjet and be done with it and have fun. Not gonna waste money on a dead end
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
Vumad said:
Read the X2 forums. Lots of people putting 750 in X2's. A 650sx and a X2 are very similar, but the SX has a larger engine compartment and will probably be more accomidating to the larger 750 pipes. My X2 is an '87 and my motor is a '94 XI SS.

My issue was fitting a 750 pipe in my X2, but the SX has a lot more room in the hull for pipes. If you run an AM 650 pipe, room is definately not an issue. The second biggest problem was figuring out what was necessary with the pump since the 650 pump can't handle the 750 motor unless you change the nozzle and get a modified 750 prop. The 650 pump will work just like you have it right now but your motor will not perform to it's potential w/o modifying the pump.

No, you cannot just bolt the 750 box in where your 650 box is at. The 750 boxes are much larger than the 650 box. The 750 CDI is about the same thinckness but is twice as wide and twice as long as a 650 CDI. The coil is also larger, so even if you take the items out of the 750 box they still take up significantly more space than a 650 electronics. You can run the 650 electronics if you modify the 750 cases. The advantage to this is the 650 flywheel is lighter and improves bottom end. If you have the electronics that came with you SS motor, simply strap the entire box to the fuel tank with the tank straps where the stock oil resivour was. (You can't mix-match, it's complete 750 or complete 650).

A 650 exhaust manifold will bolt right onto a 750 or 650 motor, but the 650 manifold will be a tiny bit restrictive compared to a 750 manifold. In anycase, if you have a 750 manifold, just use that, unless your 750 manifold is the 4-bolt style from the SS ski, then obviously that wont work. You should get the westcoast manifold that matches your pipe and it bolts right on. (btw, b4 u ask, intake manifolds do not interchange.)

The simplest thing to do is drop in the motor, buy the 650 exhaust manifold, bolt on the AM 650 pipe, might line up with your stock exhaust hoses, drill a couple holes in the waterbox baffolds (there's a post here on how big of holes and how to do it). That is enough to get you on the water. After that, bore your pump nozzle out to 85mm (from stock of 83mm) and get a 13/18 750/800 prop and have it cut by impros or someone else to work with the 650 pump. Done.
Click to expand...


Few things i have learned since this post...

Thee is nothing wrong with the 650 pump itself. It is basically exactly the same at the 750 and 800 pump. Nozzle size is part of pump tuning, and nozzles are interchangable. There is nothing wrong with running the 650 pump, except you have to buy used old style props, new custom made props or have a 800 prop cut. An impros hooker is cheap enough that you can just buy one cut right for the 650 pump.

However, there are advantages to a 800 pump in a 650 hull. You can buy used props. However, the is currently no options for intakes and pump shoes, so they have to be custom made, which is a major disadvantage. Shoes can be made by cutting the ears off of a bad 650 pump, but theres still limited intake options. Intakes are plastic or cast, so its not as simple as just welding up an adapter plate.

If you do go with a 800 pump in a 650sx, one of the 750 sit downs, i believe the 750ss, has the same driveshaft but the splines are the longer 750 cut. You can simply change shafts to work correctly with the newer pump. This is not an option on the x2, which requires the shaft to be cut. I believe @rhaas can offer the service.

Sorry for a sliht misinformation all those years ago.
 
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bored&stroked

bored&stroked

Urban redneck
Location
AZ
Midlake Crisis said:
I am curious which of the skis in your signature line you enjoy riding more?
I am really in love with my 650sx other than the lack of power.
Click to expand...
Hands down without a doubt no comparison the superjet is a million times better.
I just started on 650sx's and so have a place in my heart for it. Jumps waves well too.
 
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