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Discussion Starter #1
My Dad has a '92 907ie and is looking at an engine from an '01 ST2 to possibly swap. Does anyone have info on the issues for this swap. Also he was wondering about the pick up sensors for timing and such and how many are on the ST2.

Thanks and I know this is vague for starters but he asked if I could look and ask around for him.

Thanks.......Sam
 

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The ST2 has only one rpm/timing semsor at the water pump end of the timing idle shaft whereas the 907ie also has a crank sensor taking pulses from the flywheel. They both use completely different injection systems, the ST2 has an IAW16M ECU and I think the 907 uses a P8 ECU.
He would be best to use the all the injection components and wiring harness from the ST2 (at least the parts pertaining to the injection) and adapt them to fit the 907.
 

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An '01 ST2 engine would also have a bigger altenator, more wattage, than a 907. You may need a R/R that can handle the wattage.

907's are far and few between. It's going to hold a lot more value with the original engine. What's wrong with it, or does he just want more power?
 

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I'm kinda doing something similar....

The swingarm mounting bosses on the ST2 engine are wider than the 907. I have an ST4 engine resting inside a Paso 750 frame and I had an ST swingarm reworked to hook up to the Paso suspension. For an ST2 engine into a 907 swap, you will need to machine the swingarm bosses down to match the 907 engine or modify a swingarm to mate to the ST2 engine. Oh yeah, the 907 and 750 swingarms are interchangable (I also have a 907 swingarm).

Swingarm differences between the Paso 750/907 and ST2/4 bikes....


(It is difficult to see, but there is about a 1" difference between the gap for the engine cases between the two swingarms)

Here's the rolling chassis with engine installed....





 

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Desmo Demon That is sick! Post more pictures as it goes on. I love the Paso, still regret selling mine.:yeah::yeah::yeah:
 

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I forgot to mention about another difference in swingarms and engine cases. The Paso has the swingarm bearings in the swingarm with the swingarm pivot being stationary and bolted through the frame, whereas the ST bikes have the bearings in the engine cases and the pivot is clamped to the swingarm. I don't know how different the frame of the 907 is compared to a 750, but I had to trim down just about every engine mounting boss to fit the ST4 engine into the thinner frame width of the 750.

Post more pictures as it goes on. I love the Paso, still regret selling mine.
I'm hoping to get back to working on it fairly soon. The largest issues I have is getting the section of frame rewelded where I cut it for horizontal head clearance, and then later on, I'll need to have the bottom of the gas tank modified to clear the extra width of the 4V engine's vertical head.
 

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Terry, that IS insane!! The killer Paso they should have built!

Is that a 17" rear wheel? Can you get the under-engine frame sections installed as is or did you have to modify them?

I love it.
 

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Is that a 17" rear wheel? Can you get the under-engine frame sections installed as is or did you have to modify them?
That is a modified ST2/4 swingarm so I am using an ST2 5.5" 17" rim and axle/adjuster assembly. The tire is a 180/55-17 and clears without any issues. The chopped and stretched ST swingarm is actually the same length as a 907 swingarm, so there are no drastic geometry changes of the suspension. The largest reason I decided on running a modified swingarm was that I didn't want to have to modify the Paso frame for the ST2 rear suspension, and this way I will not have to relocate the battery. I was leery about machining the engine cases for the Paso swingarm, and I think this arrangement will work out pretty well. I have a spare rear wheel assembly for my ST2, so the new MegaPaso 916 will use that. I obtained the ST4 engine complete with wiring harness, throttlebodies, ECU, FBF eprom, and airbox, so I'm essentially trying to shove an ST4 into a Paso chassis.

The lower frame rail bolts up on the right side with no clearance issues. I have not checked the left side, yet, though. I don't really see any issues, and if it needs to be shaved or staggered around part of the left side engine case, I'm sure I can modify one (have two sets of spare bottom rails).

What's cool about this project is that I only have about $800 in the whole thing and I have everything I need to assemble it....and some spare parts to sell to drive the cost down even further. The most costly item will be to have the bottom of the tank reshaped to clear the vertical head.
 

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Discussion Starter #9
Wow thanks for the info, very much appreciated. One asked why my Dad wants to make the swap. He found the ST engine for a good deal but it is missing the intakes and a few others things with low mileage. His 907 has I believe 60+ thousand.
 
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