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Discussion Starter #1
I have a 01 996 SPS that the engine let go. I have a 04 ST4S 996 engine that I ordered. I can't seem to find much on if this will work or not.

The engine is coming with the ECU, wiring harness, throttle body and a few other Items.

I am starting to wonder if the ST4S engine will fit the frame. Any thoughts on what I am going to get into?

I have read that the cylinders may be different and may need to changed.

I have done other engine swaps, but this is my first Ducati.

Will I be better off selling this engine and looking for a SPS engine?

FYI... I think it was a track bike at one time, there is not much that is original, that's why I don't have a problem swapping or modifying it.

Thanks in advance for any information.
 

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Discussion Starter #3
It didn't explode. It has a rod bearing that started knocking. It did some damage to the crank. I don't see any other damage.

It could be rebuilt, but I was hoping to do a quick engine swap and get back on the rode.
 

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the st4s engine is from the "swingarm pivot bearing in case" family of engines (m, sc, ss, st), and the 996, like all other sbk 916 >, is from the "swingarm bearing in swingarm" family (also mts and hm).

the 996 cases are narrower at the pivot and the pivot hole is higher. if you machine the st4s cases to be narrower both sides, remove what is left of the bearings and lower the hole for the pivot rod to go through it'll be fine.

compared to a 996, the st4s engine has shorter duration inlet cams (not bad) and crappier exhaust ports. otherwise all physical and electronic parts will fit / plug in. except the front air dam maybe, due to the lower head.

no need to fit the st4s harness or ecu unless you really enjoy pissing yourself off for absolutely no reason.
 

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Discussion Starter #5
Thanks for the information!

So it sounds like it can be done. Should I swap heads, or will that cause more problems than it is worth. I did read somewhere that if I did I would have to use the belts from the 996.

I did notice that where the pipes bolt to the heads, that looks to be different. Should I use the pipe outlet from the ST4S and join them to the 996 exhaust?

That just may be something I will have to work out when I get to that point.

Knowing the engine will fit with some modifications is a good start.

Thanks again.
 

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well, it'd be a lot easier to machine if it was down to case halves, and if it's split then you can reshim the crank and do the squish when you put it back together. but then instead of dropping the heads with a thinner base gasket and having belt tension issues you can fit a 900 crank and lift the cylinders with a second base gasket and get good comp and really it all goes on from there. 996 heads is easier, but i'd not be adverse to using the st4s inlet cam.
 

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Generally, I would advise you to rebuild the original motor. If you have the mechanical ability to do a motor swap, then certainly you could pull the original motor, have a top notch shop do the rebuild, and then put it back in yourself. The rebuild might run $4K, but at least its a real SPS, and it would rip.

There's not going to be any quick solution. If you swap for a non-SPS motor then you have to do the motor, ECU, harness, tachometer, and more. It would be cheaper and far quicker to sell it and buy a 996 or 998. As mentions with the ST4S idea, then you have the whole palaver of the swingarm area. Even if you get a regular 996 engine then you still have to do the ECU and harness etc.


But we need more info...

How "not much original" is it? If it really is that bad, then it makes even more sense to sell it on to someone who has the patience and deep pockets to restore it. It would be a shame to separate the frame and cases though.

Knowing where you are would allow us to recommend a potential rebuilder--Mark Sutton/Ducshop, for example.
 

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Discussion Starter #8
Generally, I would advise you to rebuild the original motor. If you have the mechanical ability to do a motor swap, then certainly you could pull the original motor, have a top notch shop do the rebuild, and then put it back in yourself. The rebuild might run $4K, but at least its a real SPS, and it would rip.

There's not going to be any quick solution. If you swap for a non-SPS motor then you have to do the motor, ECU, harness, tachometer, and more. It would be cheaper and far quicker to sell it and buy a 996 or 998. As mentions with the ST4S idea, then you have the whole palaver of the swingarm area. Even if you get a regular 996 engine then you still have to do the ECU and harness etc.


But we need more info...

How "not much original" is it? If it really is that bad, then it makes even more sense to sell it on to someone who has the patience and deep pockets to restore it. It would be a shame to separate the frame and cases though.

Knowing where you are would allow us to recommend a potential rebuilder--Mark Sutton/Ducshop, for example.


I appreciate all the info from this thread and the site. Lots of info.

The plan was always to get the motor rebuilt. I was hoping to swap engines so I could ride while I take my time and rebuild it.
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Love the bike. Its in great shape. When I said it wasn't original I just meant a lot of aftermarket parts. Is not a "all original bike"

I have rebuild just about every bike motor there is, just not a Ducati. I knew I was going to have to buy special tools, and research a lot. I'm sure in the long run it would be cheaper to send it off, but I like to do my own work on everything.

After reading up on everything it looks like I will have a nice 2004 7k ST4S engine, ECU, throttle bodies and harness for sell in a couple of weeks LOL or it will be a good starting point for a cafe racer.

Once again thanks for all the info, it helped with the decision.
 

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You ship me your bad engine and I will ship my 996 engine with .9mm squish, light weight flywheel, and the close ratio transmission. It needs belts, but runs wonderfully. (note that the pulley sizes are different between the horizontal and vertical cylinders) The valve shims were done 200 miles ago.
 

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I'm an "assembler", but for the amount of machining, resurfacing, and getting the precise tolerances for a long-lasting motor, not to mention the titanium rods and crank bolts, I'd just bring the motor to one of about half a dozen guys in the US. The stakes are too high and their expertise is worth it.

The ST4S motor will be much better for someone building an 851/888 project.
 

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Sounds like a lot of work and the end result is one less real SPS around, one more Frankenstein Ducati. Whatever you save on the rebuild you lose on the resale. If there are two SPS‘s for sale, one with a fresh built motor, the other with extensive changes made to shoehorn a less powerful motor in, which one would people be more interested in ? I’ve been there before.
 

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I am not being a jerk, but at this point the value of the bike and what you will put into it should not have a factor on the value you want it if you plan to sell it some day.

A 996SPS with a standard 996 engine is going to sell for about as much money as a clean low mileage 996. Putting what will ultimately be $4k minimum into the SPS to have the original engine work like new or better is nice, but that figure will not have a real impact on the sales price compared to another SPS, similar miles and condition, where the engine was not rebuilt. And you know that.

How do you want to manage the machine and your money? It's still an excellent bike.
 

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Are all the modifications done to the ST4S motor to make it work or are there mods needing to be done to the frame and swingarm? In my opinion, if it's all modifications done to the motor itsself then do the swap and keep running the bike. While you are out having fun and when money is available have the SPS motor rebuilt. When it's time to sell or once the motor is complete then swap it back in. The bike gos back up to "full value" once the motor is back in. Why not, if its fully reversible without damage.
 

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i actually just did this a month or so ago...except mine isn't an SPS. i took the ST4S motor right down to the cases and machined the swing arm pivot area. i also re-shimmed the crank, set piston squish, lightened the stock flywheel and primary gear. currently getting it set up for some cam timing. hopefully in the next evening or two.

my opinion...rebuild the SPS motor and stick it back in. originality is always nice when it comes to rare bikes.
 
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