What to do ?

CSH

Hi fellow duc lovers , i purchased an SP2 in good condition 22.000 Km on the clock a few months ago, the bike has been sitting for years and rubber hoses ect.. have gone brittle.
I did not have the time to start work on the bike yet but now that winther is here i will find the time. since i bought the bike i stumbled on a 926 motor with double injectors and a one pice carbon airbox as well as some Øhlins FG 9051 forks and a set of Marchesini 3 spoke mag wheels, all in my workshop now :-)
The SP2 is almost standard and looking good ! my intention is to use it for very spirited road riding but mostly track days.

Should i build a tool for the job out of my SP2 and the above parts or find a strada to upgrad on and leave the SP2 as ornament in the livingroom, i am worried that i will ruin the value and collectability of the SP2 if i start building.

What is the oppinion of the forum, leave the SP2 standard or build it ?

Plan is to further increase the race potential by adding some Oronero100 parts such as the corse style ramair and expansion tank and fuel tank.

I am no wizard with engines but would appreciate som info on the 926 motor configuration, what power output should i expect, how will reliability be in this trim:

31/37 valves
Domed hi comp pistons
926CC
Pankel rods
race cams (not sure what type, but i have newer seen so much lift on a valve before)
mag engine cover
light and balanced crank
Alu clutch
light flywheel
(engine casings are the later 1995 stronger version with now engine number)

This is not my only duc i have a F1, 900SS, and 996 as well but the 851 is to me as good as it gets.

This being my first post i would like to thank all of you for this wonderfull forum i have been reading the archives for months and have both learned from and enjoyed the process, finally got the courage to expose myself to the pack.

Christian

sp2 boy

Welcome you lucky boy!

Unfortunately the fixed cross brace in the SP2 will not allow you to fit that one-piece airbox...🙁

BUT you can always get another frame or complete bike to make a real special bike...remember you need the later type frame for that air-box or cut the cross brace and make it removable like the Corse bikes...Marvin did this on his. 😄

Mr.R

Hi and welcome to the forum,

Nice collection of parts there, the comp' ratio won't be that high with those pistons as the deeper/wider valve pockets for the 37/31 valves/Hi lift cams will lose quite a bit of comp'.
As to how much power? It depends on the cams, eprom etc, a well prepared 926 with 431/G cams should kick out close to 135rwbhp at 11,000+rpm (maybe as high as 12,500rpm 😯 ) which isn't good for longevity/reliability.

2 forum members have Corse/Corserised 955cc motors and these make around 135rwbhp, Neil Mason's 955 had 36/30 valves and made it's peak power at 12,500rpm.

Steve R

CSH

Thanks for the welcome.

SP2 boy: i am aware of the cross brace in the earlier frames, that is one of the main reasons i am hesitant to start work on the SP2, i did look at that picture of the modified frame contemplating to do the same thing, i think i will get a donor bike to make a "race use only" bike of the parts, may be the smartest move.

Mr R thanks for the info on 926's i have been browsing the web looking for info but i think the 926 is likely the least discussed bike in history.
How can i identify what cams i have ? and do you have a supplyer for a chip ?
I have been looking at the Sil full spaghetti system it says it comes with a chip, however i suspect that it would only work in a standard motor with the full system and not my 926.

dan851

Congratulation on that bike.
I have looked at the SP2, so Many times on DBA. I would leave it standard. And build a really hard trackday bike, with those beautyfull Parts.

Mvh Dan

Mr.R

Hi Christian,
The cams should have part numbers marked on them, if not you'll need to check the lift and duration then compare these to known figures.
Unless you can find a 926cc Corse chip you'll probably have to get the motor custom mapped, should really do this any way.

Personally I ditch the race cams and fit 996SPS cams, you'd get most of the power without the extreme rev ceiling, making for a far more reliable motor that will actually tick over/idle under 2000rpm.

Steve R

CSH

Dan: thanks, i was looking at it for months trying to find the cash, lucky it was still there when i finally got the money. must say it was a surprise that it sat for so long and no one went for it.

I will wait and see if i can find a cheap possibly wrecked strada during the winter and build a proper race bike from that and the parts, if you guys hear of any wrecked bikes in northern europe or UK for sale please give me a hint.

Steve: I will look at the cams and see if i can find the labeling, dont think i will go for changing the cams as i dont mind the rather extreme profile of them, to my eye they look a lot like the pictures on here of the Fallappa endurance racer rebuild, the engine in that looks identical to the one i have.
135rwbhp would be more than enough for my needs and it could be fun to have a motor that is in RACE trim.

running this kind of motor, what are you guys experience, do they:
- need a rebuild between seasons or more oftent
- when rebuilding is it just a bearing exchange or are we talking, rings, valve gear and gearbox.

The last thing i want is run it for too long and hear that dreaded BANG !!!

Christian

AJV

Congratulations on your purchase Christian, I think in years to come the SP2 will be the SP (SPS excluded) to have because of the low numbers produced and its significance in being the link between old/new performance Ducati's that worked properly time will tell!!

What a nice problem you have and fair play to you for wanting to use the bike in the manner its creator intended, if its power you want for track use, mothball that original engine, sure you can tune them but those cases won't handle prolonged use with high revs

Best option in my opinion is get yourself a low mileage ST4S, fit the engine/ ancillaries and cane the bollocks of it. Those cases are much stronger and if it breaks spares are readily available. Sell your 926 engine and you've almost got the funds to buy an ST4S

Don't forget order of priority for track days upgrades, rider, tyres, brakes, sorted suspension, light wheels and then power And get some cheap bodywork.

Enjoy your new bike.

Andy

Mr.R

Well put Andy,
I was going to post...
"Who wants to tell Christian about the 500 racing miles crankcase life?"

With 37/31 valves, 926cc and full race "G" or 431/G cams, the 926 if used to the max would be something of a hand grenade with the pin already 1/2 way out.😯

It's for this reason that I favour 996SPS cams as they produce good power at under 10,000rpm.
With these cams timed at 107/107 CL's, flat topped pistons, 35/30 valves my 851/916cc motor hits 128rwbhp at 9,2-300rpm, well on the safe side of 10,000rpm. It also pulls like a freight train (76.5ft lbs/torque) from 5,500rpm and happily ticks over at 1,400rpm.

Steve R

CSH

Andy and Steve; must say i am getting a little bit of cold feet regarding the whole 851 racer, idea you guys shure know how to encourage 😉
I simply can not afford to swap cases or vale gear at 500 race miles or even at a 1000 miles, as steve puts it it is a handgranade with the pin half way out 😯
Seems that i should rethink my options then, i have a 996 that is close to track worthy, it was my original intention to race that, but then along came the parts above and plans changed, given the good feedback you guys are giving the 851 bells and whistles racer route seems a prohibitively expensive and distant dream.
think i will put the SP2 in the living room and ride it a few 100 km a year just to give it a work out.
Prep the 996 for race and leave the motor stock so it wont blow up on me.
Then if i can bring myself to do it, sell the parts above, damn !!!!!

It pussels me a bit that these motors are so demanding on the wallet, i have an aircoled SS with high comps, bigbore, bigger valves, carillio rods, light crank, light flywheel, stm slipper clutch, FCR's and all that, the motor did 100.000KM in standard trim, i did the rebuild as described and have done the bearings and that at 15.000KM intervals since no problems at all. I understand the trim of the 926 is more extreme, but really that much ?

As you guys must have picked up i am very new to the race seen and have only been a road rider up to now, love it but the sunday drivers are getting on my nerves.
I truely appreciate the info you guys are giving and intend to make the most of them, as i said i am new to racing, i dont have an infinity bank account, I love 851's and just want to have some fun.

How to make the most of it ?

Christian

MarkT

Christian-

I have an SP2 and about ten years ago I crashed it and decided to make it a full Corse. Every part except for the motor, wire harness, and swing arm are Corse and it is fun to ride. But if I was in you shoes today I would keep it stock. Stock it is a very nice road bike and I believe that a stock one should be preserved. Eventually I am going to convert mine back to original and use the parts to make another bitsa Corse.

marvin

FWIW, I believe it is the high RPM's that cause the cases to crack more than anything. If you put SPS cams in it and kept it below 10K you should be OK. AS Steve has said, the SPS cams will allow you to make nice power below 10K, the G/431 won't make good power that low.

Or even Strada cams. They won't make the power that the SPS will but it will still be a nice engine, just not the fastest one on the track.

Mr.R

CSH wroteIt pussels me a bit that these motors are so demanding on the wallet, i have an aircoled SS with high comps, bigbore, bigger valves, carillio rods, light crank, light flywheel, stm slipper clutch, FCR's and all that, the motor did 100.000KM in standard trim, i did the rebuild as described and have done the bearings and that at 15.000KM intervals since no problems at all. I understand the trim of the 926 is more extreme, but really that much ? Christian

I doubt that your SS is making anywhere near 130rwbhp and it can't be reving to the wrong side of 11,000rpm.
The earlier 851/888 C/cases were a lot weaker and as has been said it's the high rev ceiling needed to make good power with race cams that kills them for a pass time.
"G" and the 431/G combination make their power on the wrong side of 11,000rpm some motors as high as 12,500rpm.
If you were to fit the 996SPS cams to the 926 with it's 37/31 valves, I'd be astonished if it didn't make 130+rwbhp at under 10,000rpm, if the engine builder knows what he's doing.
A standard ST4S motor with a full race system and custom mapped fueling would be lucky to hit 118rwbhp, it would be pretty bullet proof though.

Late ST4 C/cases are the way to go if building a hot 888/926/955, they incorporated all of the lessons learned from the 851/888/926 race programme.

Steve R

sp2 boy

MarkT wroteChristian- I have an SP2 and about ten years ago I crashed it and decided to make it a full Corse. Every part except for the motor, wire harness, and swing arm are Corse and it is fun to ride. But if I was in you shoes today I would keep it stock. Stock it is a very nice road bike and I believe that a stock one should be preserved. Eventually I am going to convert mine back to original and use the parts to make another bitsa Corse.

Mark, you really have some lovely toys, both two and four wheeled...go on tell us that you are retired and have plenty of time to tinker with your toys to make us all really green with envy! 😁 😁

Well done... enjoy your time away from working the grind stone. 😄

😄

MarkT

sp2 boy wroteMark, you really have some lovely toys, both two and four wheeled...go on tell us that you are retired and have plenty of time to tinker with your toys to make us all really green with envy! 😁 😁 😄

Yup- retired from NASA. I was the senior engineer for the Hubble Space Telescope and retired after our last mission in 2009. Aside from all of the paperwork, I had great fun designing replacement hardware as well as working with the astronauts developing tools and methods to repair and replace the hardware on the Hubble.

Here is a picture of my surprised ugly yap that my wife took taken today-

sp2 boy

😯

You look younger than me but I haven't retired!

Here's a picture of me that Scott took last year at Stafford...

I only look marginally younger when I remove my locks. 😄

griff851

Hey Mark, were you in that documentary with the screw catcher?
Ok Pete, I'm scared now, I'll take the present😁. Don't want to be messing with the national front bro's😁.

Christian, If they are not "raced" they are fine. Its just above the 10k zone their life reduces somewhat. The service interval for a modern bike stuck on the track is 2500k. The boffins were on the edge trying to win titles. Cases cracking, was part of the gig. As Steve and I found out roller bearing mains are great for load, but only have about a 15000k life. They discovered many things back then. All part of the history.
I'd score another engine, and give it some treatment and go have fun on the track with that installed.

MarkT

griff851 wroteHey Mark, were you in that documentary with the screw catcher? .

No- they normally pick the young engineers for show and tell to inspire young people to want to work in the Aerospace industry. I designed a version of the screw catcher and it was given to the young engineers where it evolved into the one you saw in the documentary. As the senior engineer I would provide the first "challenge" design because I wrote the requirements for the hardware builds. I would machine them up in my basement, test them, and then give them to the team.

Ok back to Christians question.

From your last post you are understanding that unless you know the history of these Corse motors- hours on motor and number of rebuilds, there is still some risk to the case even if you install SPS cams to keep the revs down.

It could be that for its last rebuild the case was replaced. Can you post a picture of your case? The last ones cast have no kick start bung on the right side. They also do not have an image of an elephant on the top of the case- they have a date stamp instead. If you have one of these cases then you may be good just installing SPS cams and doing light track days.

If you do not have the newest case on your motor you may be able to tell if it has had a rebuild by seeing if there is a hand stamped number on the top of the case.

Many engine builders will stamp a number on the cases to indicate what rebuild they are up to. For example some will stamp 2 and the rider number on the case-- so 223 would be the second rebuild for rider 23's motor. I have not seen a case go past 2 because the hours are high enough at a third rebuild to replace the case.

If it has had two rebuilds then there could be high hours on the motor.-- Not saying you should not go ahead and install SPS or 888 cams (not sure how 888 cams would work with big valve heads) but you would be taking a bit more risk.

I am not sure what chip is out there for a duel injector, 926 with SPS cams.

One thing to think about is that an original 926 Corse motor with a good case will be rare in the future. An owner of a Corse may pay you good money for your motor.

Mr.R

851/888 Strada cams are the same grind as 996 Bip cams, with the 996 running 36/30 valves but they don't make fantastic power.
I think that the ported/flowed heads wouldn't suit Strada cams, you'd probably end up with a dog.
996SPS cams like big valves, but if the 926 heads have been properly done to suit the cams installed they might not suit anything else.

For a 926 chip you could try John Hackett/JHP Coventry Ducati, but a 888 Corse chip with a PC III Usb used to fine tune it would do the job.

On another note when I rebuilt my 851/916 motor the last time, I replaced the main bearing bushes/housings and I was surprised how much damage there was in the cases where the crank had been trying to hammer it's way out of them upwards between the V.
Having seen this I'm not surprised that the high revving Corse motors killed the cases in double quick time.

Steve R

MarkT

Mr.R wroteOn another note when I rebuilt my 851/916 motor the last time, I replaced the main bearing bushes/housings and I was surprised how much damage there was in the cases where the crank had been trying to hammer it's way out of them upwards between the V. Having seen this I'm not surprised that the high revving Corse motors killed the cases in double quick time. Steve R

When I pulled down my 984 motor which has 888 cams - the races fell out of the case from the beating of tracking the bike. I red locktited new ones in and the motor has been fine but even with low rev motors you can over rev them from time to time and beat the cases up-- of course this long stroke does the case no favors when you do over rev--you pay going in or you pay coming out.