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Discussion Starter · #1 ·
The post below has me considering a similar avenue as the old engine in my SS is in pretty rough shape and may have some hidden/ unkown issues according to the previous owner...

i am pursuing the route of having this 750ss rebuilt, but since i'm purely interested in having a running and riding supersport i am considering the options of replacing the motor/ rebuilding the 750 with performance parts/ or even some amalgam or frankenstein bike.

questions:
-the 1991-1998 bikes are pretty similar so would a swap from one of these be my only option?
-would any of the newer injected bikes be a better/ more cost effective option (2000 models up)
-would a carb'd 900ss fit and not need much to swap? i see some wider numbers on the 900 than my 750, but i think it uses a spacer to match up to the rear wheel?
-are there great performance mods/ big bore options for the 750? i know the 900 has plenty (feracci)
-from a cost / benefit side would i be safe in assuming a rebuild by a reputable shop would run me the same as purchasing a ready to go engine from another bike? (some quotes in my area range from 3k up to 3 times that)

-i have always wanted a supersport and WILL own one, but i may have bitten off more than i'm capable of with this little project.

Thanks for the input, i'm just brain-storming from the office desk chair and would like any info on what you folks have done.
 

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A total rebuild by a pro will be very expensive. Use the Search feature, there are many posts about what engines will interchange, but I think basically any 2 valve engine from a Monster or SS will work. Obviously there are minor differences that have to be addressed. To me, the important part is finding a good used motor because it would be really irritating to install a motor and find it has issues. There are reputable bike breakers on eBay that will verify the motor, even showing you a video of the running bike.
 

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Well I do need to get to work and I don't have the time right now to fully flesh this one out but as a start...

Building the 750 motor.

1. keeping it correct for down the road when you/someone else wants a original 750ss.
2.0750ss cases were good for reliability if power was kept below 80rwhp after that you would shorten case life.
3. Avoid the later version of the cases , In the US we did not get the 750 after 93-94 and when it came back in 97 the cases were NOT the same in that case life was far too short. I have personnaly
cracked 2 sets of 97 750 cases with stock power output.
4. I like the look of the early motors as they look ... well better to my eye for some reason.

Fitting post 98 small motors.

1. Not a issue in fit if you but the right one a 98 750 monster motor was still carbured so it has everything you need to drop it in. You will need to change the rectifier and will need a front motor mount bolt but IIRC that was about it. The clutch line shouold reach as you do need to relocate it from the right side to the left.

2. these later motors can be built as they were more robust cases so feel free to build a little hotrod, 90.5mm pistons were available and there are cam options . A good streetable motor should be able to get into the mid 70's rwhp

3. injected motors do fit but may need more work. motor mounts are bigger, you need to buy parts to convert to kokosan or ignitech ignition. I converted a 800 s2r motor to a carby for a customer a couple years ago, we kept the long manifolds and did nothing to the motor other than a light flywheel and a tune. In her 98 m750 that 800 motor keeps much of the caricature of the original motor but she gained a 6 speed gearbox, factory slipper clutch and a better platform to build from if she chooses. In the carby form she is down about 2-3 hp over the short manifold (s2r) bikes but is 5-10rwhp stronger down low over the same bikes.

fitting 900 motors.

1. exhaust header and carbs should be it to get you going.

2. early 900 motors did have more issues than 750's so research what you are buying.

3. late 900 motors were less problematic but will require a change from injection so as above more parts are needed.

4. best mix of stock RWHP and torque so reliability should be good without building yet you can build to higher levels with cases having few issues of breaking unless you are pushing big numbers.

6. dry clutch- more bling than anything but hey if you like them why not?
 

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I would love to know the ins and outs of putting the sr2 800 in the 98ss frame and running it on carbs if you were to find the time to elaborate ?, cheers.
 

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Not much time today but in a nut shell .

Stock carby carbs and manifolds.
800ss exhaust (head height is shorter than 900 so small motor exhausts bolt up) .
Ignitec ignition plugged into crank angle sensor is the easiest way to get ignition.

You will need to drill out frame to take 800 motor mounts or sleeve motor mount holes in engine, your choice both work fine.
 

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Yes be sure to buy an engine with the correct bearing location. In the cases NOT in the swingarm.
 

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You will use the SS rear sets and the shifter location is the same on the engines so another bolt on item.
 
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