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Discussion Starter #1
Hey everyone. I haven't posted anything outside of the classifieds in a while and thought some people may be interested, so here it goes.

I picked up a near complete 02 ST4S from a gentleman in Buffalo NY. He grabbed it from an auction with plans to rebuild it. It had a salvage title. Life happened and he decided to sell it. I sold off most of the bike but still had the motor and electronics. I looked around the shop and thought to myself, I have almost an entire bike here...748 frame, swinger, suspension, triples, etc. I miss my 748 track bike dearly...so what better than to build its big brother.

Biggest hurtle was that the cases on the ST4S motor are different at the swing arm pivot than the SBK's. quite a big wider actually. I knew I wanted to go through it because I didn't know the history of the bike well so I figured it wouldn't be too bad machining the cases at that point.

I started tearing it down and to my surprise, the motor was in pretty nice shape. It had less than 20k on it so I wasn't too worried. The bike was full of aftermarket cosmetic goodies so the previous owner seemed like a "spare no expense" kind of person. The nice red motel oil came out clean which was a great surprise. And they were running engine ice which was a good sign.. it was also clean.

Once the motor was tore down, I started measuring things up. I reshimmed the crank preload to .15mm. I read that a few people on the forum were going that light so I thought I'd give it a try.

I had a 748 motor that I tore apart at the same time to take the close ratio transmission out of and put it in the 996. I checked the shaft freeplay and that was in spec so all was well. I also took the flywheel and large primary gear and lightened them. I removed 2.4lbs from the stock flywheel and .35lbs from the primary. A lot of rotating mass! I would have loved to send the crank out for a knife edge and balance but budgets have to be kept in mind right now.

Right now I've got both sides of the lower end components mounted and torqued. I just cleaned up the carbon from the pistons, cylinders and heads. Then I lapped in the valves to the seats, adjusted the valves and replaced a flaking opening rocker. Once my thicker solder comes in the mail, I'm going to measure/set piston squish...then cam timing...then start assembly of the bike =)

I'll update as time goes on. Enjoy
 

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Wow, with removing that much mass from flywheel and primary, that motor should spool up a good bit quicker. Nice work. Thanks for sharing.
 

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Discussion Starter #4
generally you need to machine 0.4mm off the bottom of the cylinders to get the squish in the 0.95 - 1.0 mm range.
Both cylinders measured 1.35mm. Pretty much what you said belter! Done this a few times, eh? Hahah
 

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I hope you are happy with the build, but we don't get much out of these engines without the SPS cams and some top end work. They are still fun engines that pull hard and you can keep up with modern machines if you ride it right.

Stock cylinders without a base gasket can get you down to around .9mm to 1.0mm with a Cometic head gasket at 1.0mm The close ratio transmission if fun, but you hit redline fast in 6th and will look for more gear on a strait even with a 15/38 gearing. That doesn't really matter too much b/c 2nd-4th are more fun. Quick to 120mph or 130mph depending on the gear you are in.

If runnig it hard, which is the correct way to run it, go ahead and put a slipper clutch in there. Without it, that rear end hops around a good bit before coming into a turn and can affect your line and throttle. You can get used to it, but it's still works you when you are really hard on braking and shifting from 4th or 5th to 2nd after a good speed.
 

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Discussion Starter #10
I hope you are happy with the build, but we don't get much out of these engines without the SPS cams and some top end work. They are still fun engines that pull hard and you can keep up with modern machines if you ride it right.

Stock cylinders without a base gasket can get you down to around .9mm to 1.0mm with a Cometic head gasket at 1.0mm The close ratio transmission if fun, but you hit redline fast in 6th and will look for more gear on a strait even with a 15/38 gearing. That doesn't really matter too much b/c 2nd-4th are more fun. Quick to 120mph or 130mph depending on the gear you are in.

If runnig it hard, which is the correct way to run it, go ahead and put a slipper clutch in there. Without it, that rear end hops around a good bit before coming into a turn and can affect your line and throttle. You can get used to it, but it's still works you when you are really hard on braking and shifting from 4th or 5th to 2nd after a good speed.
Our local track is pretty tight so the close ratio tranny will work nice. Maybe ~140mph on the straight and you're back into turn 1. I had a 748 track bike a couple years back that was set up with a slipper and quick shifter. Definitely the route I am heading for again. I ordered my cometic base and head gaskets this morning so hopefully see them next week.

I would have loved to put better cams, HC pistons and lightened the crank...but a budget had to be kept in mind with this build. (Just built a house last spring, still dumping money into projects). I'm using mostly parts I had laying around the shop plus a few things here and there that needed to be purchased. Over the years to come I'll acquire stuff as it pops up. I'd rather spend money on suspension next though.

Thanks for all the tips/info so far everyone!
 

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The transmission will be fine on a tight circuit. What's really nice is the pull in each gear. You can muscle through low-mid rmps in 4th where typically you want 3rd. But then there is gearing that factors into it.
 

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Discussion Starter #12
Have any of you guys played with cam timing on the ST4S version of the 996? Just wondering If I should keep them at Ducati's spec or adjust at all while I'm doing it
 

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Discussion Starter #14
Do the timing gears, but not the ST4 cams. The ST4 have a different profile than the SBK A1. OEM spec is all over the place, and will also change after adjusting squish.

Thanks Brad: BikeBoy.org - Ducati Cam Specs
Interesting! okay thanks for the tip Namor. I actually have a set of 748 heads that I can steal the intake cams from. another 10° of duration can't hurt! looks like the exhaust cams are the same opening/closing between the two.

Now, i'll be running the 5.9 ECU/harness/dash from the ST4S. Will running the SBK A1 cam affect anything as far as the tune in the ECU goes? I plan on having it sent out for the DP tune unless you guys think I need to go another route?
 

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The ECU map will vary. I don't think it should be an issue for now, but somoene who has more experience on the 5.9 else needs to chime in.

It's not going to hurt to use the ST4 cams for now. I have not used them so I cannot speak from experience on them.
 

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use the st4s cam, it's a better cam than the a1. i usually advance them a degree or so to 113, and run the exhausts at 110. setting the squish will retard the cams a few degrees, and with the st4s heads you may need to fit some adjustable pullies to get the timing where you want it, or fit offset keys to the timing shaft as well. the exhaust cams already have 16 degree keys in them, but it depends which way you need to go.

use the original 996 ecu. i don't understand why you'd go to all the trouble to fit a 59m.
 

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Discussion Starter #17
use the st4s cam, it's a better cam than the a1. i usually advance them a degree or so to 113, and run the exhausts at 110. setting the squish will retard the cams a few degrees, and with the st4s heads you may need to fit some adjustable pullies to get the timing where you want it, or fit offset keys to the timing shaft as well. the exhaust cams already have 16 degree keys in them, but it depends which way you need to go.

use the original 996 ecu. i don't understand why you'd go to all the trouble to fit a 59m.
The reason I'm going with the 59m ECU and electronics is because I have have it and it cost me $0 LOL
 

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Fantastic Abbott!
Looking forward to hearing the results of you testing it out..
Did you go with the 900SS crank for the extra capacity or did you stick with standard capacity?
Will you be getting it tuned on the dyno? What exhaust and chip are you running?
 
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