A prize (surprise) in every box!!

got2dv8

So as my project motor (bike) lingers on... What's my project, you ask? Well, let me expand. I wanted to turn my '90 851 into a high compression 888. I got some St4 jugs for the 94mm 888cc displacement. Picked up some S4 tbs... but may use the stock 851 units. Got a P8 so each cylinder can be tuned. Also some lightened parts such as clutch basket/drum... and in the future flywheel and adj pulleys. Then I bought some 748 heads because of the bigger valves 33/29 as opposed to the early 851's 32/28. They will have the combustion chamber modified by a skilled craftsman as well as a three angle valve job. Then I got the news... I need to replace or refinish many rockers from the 748 heads.😯 That sucks as some of you know. Now, if I am going to do the rockers then I should probably go with the MBP collets. Except..they are expensive. So, my project is on hold until my money tree starts to produce.

Sorry to string you along but here comes the surprise.😁 While taking a closer look at my stock (I thought) heads, I decided to measure the valves. What's this? 33mm? 29mm? Now, I better measure the jugs... 94mm???😄 Damn, I have... I bought an 851 that is really an 888!!! The guy who sold it to me didn't even know. What a dork! Well, that's good news and bad. Good news because I have an 888 but bad news since i spent all my money trying to build an 888. I have however decided to go ahead with my project... and use the new parts to create my project engine. That way I will have a rebuild hot motor along with spares. Someday.... Maybe next year I'll get to ride it... It's already been one year.

Robert
never been kissed by an 851...

jr60

Quite a common upgrade that may have been carried out in the life span of the bike (yours came from the UK Robert?). The last of the 851's (92) came with the bigger valved heads as standard but still 851. There should be a date stamp on the top of the head (91 etc) that should tell if it is a later 888 or earlier SP setup.

Have even heard of strada's having SP engine bits or full engines fitted at the factory - ie no more strada heads/engines at the end of the month, stick in one of those SP ones in it sitting over there!

got2dv8

jr60 wroteHave even heard of strada's having SP engine bits or full engines fitted at the factory - ie no more strada heads/engines at the end of the month, stick in one of those SP ones in it sitting over there!

I just checked... my heads are stamped '90. That's pretty cool, SP heads and cylinders. Too bad they didn't throw in tb's w/ dual inj.😁 Thanks for the info!

Robert

Mr.R

Hi Robert,

The early SP's would have had twin Reds, the '90 Strada's probably had single reds at the time??
Not very good!
Single Greens are good for 65bhp each according to Weber UK, so unless your bikes making over 130rwbhp you should be OK with the single Green injectors per cylinder set up.

On another note the Sp2,3 and 4 heads are exactly the same part as the 916 Strada's, I've seen heads boxed and labelled with the part number saying they're for both bikes.
Apart from the cc of the combustion chambers these heads are the same as those fitted to the '92 851 Strada.
After that it's the SP cams and the bigger headers that make the difference in performance of the heads.

Steve R

got2dv8

Mr.R wroteHi Robert, The early SP's would have had twin Reds, the '90 Strada's probably had single reds at the time?? Steve R

I've got the single greens w/ the red tps (but will use black). Yeah, I know they're(single) all I will need. One thing to note is the tb's are cast to be used for single or doubles whereas the newer tb's (S4) don't have these castings.

Robert

Mr.R

Yes Robert the early type TB's had the casting ready for machining for the extra injectors.
However IME it's far cheaper to buy a complete set of twin injectors per cylinder TB's from a 996 etc from E-Bay, than to get these original bodies modified.
I picked up a complete 'Low Milage' set of sidefeed Green twin inj' per cylinder TB's from a 916SP for under £100.
I also bought the complete topend of the motor.

The red bodied TPS's are exactly the same as the black ones apart from the colour and the age of the unit.
As I pointed out in my 'Which PC III usb?' thread, new TPS's intended for the Ford Cosworth 4x4's can be bought new for well under 1/2 the price that Ducati want, I've got one on my bike at the moment and she's been running for the last almost 10 min's quite happily.
I'd have taken her out for a test ride this evening as the sun's shining, but Mrs R's gone out 'Keep Fitting' and I'm in charge of the little 'uns tonight.

Earlier this evening I removed the heads from a friends Roundcase '74 750Sport.
I've busied myself stripping/decoking the heads, I'm going to give them my personal touch for him. 😉
Blueprint the topend,clean up the porting etc...

Steve R

Claire4dukes

If you check the engine number stamping either 851 or 888 will appear in the number on the casting, that may tell you if it was originally an 851 or 888 motor or a kit upgrade.

got2dv8

My engine no. is 851 so by definition it is an 851. However, seeing as the heads are of the same year as my bike... I would surmise that it's not an afterthought upgrade... and more likely a factory hybrid.. otherwise, why no just install cylinders and heads from a newer year? It's kind of cool. But like I said, I kick myself for not checking initially. But, how many of you would have thought to do so?

Robert

Claire4dukes

We have an 1991 851 with a single injector 888 motor fitted, there was a factory run of 500 done for the Italian home market in 91/92. The castings are stamped 888. Ian Fallon does a book on all the Ducati models with the relevant numbers.

91/92 was a bit of a cross over year for the 851 model, some with M1Rs fitted and others with Showa USD front and Ohlins rear, both with 851 motors; the Italians also got an 851 "parts bin special" with the 888 single injector motors; this was a forerunner to the full on 888s

Cheers
Claire & Nigel