How Much is to Much?

dbenson

Top to bottom rebuild. 1994 888 LTD. Powder Coated Frame, Bucket, Sub, Wheels and Hoop. Ohlins R/T (built by Brad Miller to preserve the original triples) with Radial master/slaves, Toby damper, SP lower brake mount with support (not a monster unit). Top down Engine (851 Core as to preserve the original motor), millenium bored and coated 94MM==>, 12.5:1 Ferracci Pistsons, No Flywheel, Corello Rods, Close ration tranny, 996 Oil cooler, DP 6RAMP BB slipper, Termi italian dinner 50MM system. Carbon Front panels sans blinkers. Corse Carbon rearsets. She spins to 11,5K without any complaints and handles like a redheaded stepchild. Hope you enjoy them! Questions welcomed (I am the wrench not the owner). //db

dbenson

Last

dbenson

Pre-Spaghetti system.

dbenson

Pre-Spaghetti system.

marvin

Beautiful!!

glenn Twite

Hmm

Simply,

Sex on wheels.

Fatirossi

Great job, the bike looks awesome 😁

RWG

Well done

O yes, even today its hard to imagine a better bike.
Congrats
RWG

Mr.R

Hi,
The bike looks lovely, you should be proud of putting that one together.
But then how many 851/888's don't?

You say that its running without a flywheel, what ingnition system/ecu is it running?
Is it a 1.6m unit?
If it's still running a P7 or P8 how is the motor triggering the sparks etc, as these units pick up 1/2 of the info' needed from the 4 poles on the flywheel?

It's an 851 opened out to 888, Carillo rods, 12.5-1 comp' pistons and a spaghetti system* which nows revs to 11.5K.
What other tuning have you done to the motor, camshafts/valve timing, porting, valve seat angles, valve sizes, crankshaft lightening/balancing etc?

Did you know that if you skim the heads by 1mm and set the squish at 0.9mm it would have a comp' ratio possibly greater than 12.5-1, with a better combustion chamber shape?

If the bikes still running P7-P8 what chip have you fitted, custom map, PC111 usb?

Have you had it on a dyno?
If so what power/torque is it now making and at what revs?

What revs will it pull on the road/track in top gear and with what gearing, 15/36 15/37 etc?

How long do you think it'll last if regulary revved to 11.5K before the crankcases break?

The 851/888 crankcases are prone to crack around the main bearings and between the V if subjected to high revs too often.
Raymond Roche is rumoured to have got through 30 (yes 30) sets of cases in his championship winning year.
There's also lots of cases where SP851/888's have broken in this way due to the rev ceiling being over 10K, funnily enough I think they redline at 11K.

Which's why a lot of lads use cases from the ST4's when building a hot motor as these cases are way stronger, as they incoporated all of the leasons learnt from the 851/888/926 racing days...

Or tune the motor to produce it's power lower down the rev range.
This's the route that I favour as I have to pay for the repairs if my motor lets go. 😯
I've got all the parts together to build a longstroke 984cc with a set of new ST4 cases, which should hit/make a reliable 130 rwbhp@9.5K.
*I've got 96mm Pistal Hi comp' pistons, 900 2 valve crank,(+4mm stroke over a 851/888 crank) Carillo rods, carbon Corse airbox/X shaped runners, full 50mm spaghetti system, close ratio tranny etc.

My 'Mildly' self tuned/built '92 851/916cc hit 116 rwbhp@9.5K using completely standard (unskimmed) 916 heads, valves, pistons etc and some cams better suited to bigger valves.
It's now covered over 8,000 miles in this state of tune apart from a main bearing swap, when the Corse roller mains developed some alarming vibes.

It's quite easy to get big power from a 851/888 as they're basically the same motor as the last of the Desmoquatro motors, like the 996SPS or the 748R both big valved high revving motors and the RS versions of these motors, if you fit race cams like the 431/G combination and bigger valves.

The trouble is that high powered high revving 851/888's won't last very long and the service life of the internals and the C/cases will be dramatically shortened.
So the real challange (or closely kept secrets?) is to build a motor that will kick out decent power/torque and stay together.
I've heard of tuners getting good results using 748R inlet and 996SPS inlets as Exhaust cams, using 36 or 37/31mm valves with peak power coming in at below 10K.
I quite fancy trying these, but lack of cash and the fact that I've already got a set of V-Two 604 cams (996SPS rip offs) and some 916SP heads fitted with 35/31 valves means that it probably won't happen.

What are your thoughts on these points?
I'd love to hear what you've done to this motor in greater depth and how you managed to get it to spin happily to 11.5 rpm.

You did say that you'd welcome questions.

Steve R

P.S. I do all of my own wrenching.

P.P.S. What clipons did you fit? I'm looking for some to fit to the 'Period' Ohlins FG9050 frontend that I bought earlier this year.

jr60

Beautiful work there, well done - nice mix of original with a bit of (but not too much) bling.

Steve;

I have a spare set of corse clip-ons that fit the ohlins forks if your interested, however they are shorter than the strada ones and you have to remove the switch gear.

I just cleaned up the inside of the strada ones, opened them up a bit and they do the job perfectly.

Jonathan

Henrik

Beautiful bike, I would also like to be capaple of making that finish!

If it's to much is a matter of personal opinions. Personally I thought that I would not go for radial calipers on such an old bike, but your pics have changed my opinion on that one. It looks stunning.

I would definitely not go for a gel seat on a sportsbike, it's kind of touring.. But thats only my personal view.

Brgds
Henrik

stafford

Really top looking bike there, now how did you fit the R and T forks in the standard yokes?

narcos

Very nice result, DB. A beauty...
I was wondering what type of wheels are those?😳

darkmonster

Very nice.
Please what is this fork ?
Thanks 😉

Mr.R

Henrik wroteBeautiful bike, I would also like to be capaple of making that finish! If it's to much is a matter of personal opinions. Personally I thought that I would not go for radial calipers on such an old bike, but your pics have changed my opinion on that one. It looks stunning. I would definitely not go for a gel seat on a sportsbike, it's kind of touring.. But thats only my personal view. Brgds Henrik

Hi Henrik,
I agree with you about the look of a gel seat on a sportsbike, however I use a 'Corbin' seat pad it might look 'Kind of Touring' but...
It's not unknown for me to cover 1,000+ miles over a weekend and I can tell you that the standard seat pad isn't that comfortable over those sort of miles. 😯
...and when I'm sat on it nobody can actually see it. 😉

It's not always about how a bike looks, rather it's about what it's like to ride.
I ride my '92 851/916cc everyday.
Well until I finally get my lazy arse into gear and finish my old 301 MZ's rebuild, when that's done I'll get back to rebuilding my '74 250 Desmo and get the 984 motor back up on the work bench.

Steve R

marvin

I bet those Corbin seats are really nice for "hangin off"! That edge would hold firmly in the crack of your arse!! 😁

Mr.R

marvin wroteI bet those Corbin seats are really nice for "hangin off"! That edge would hold firmly in the crack of your arse!! 😁

You're not wrong there Marvin! 😯
But these days on the road, hanging a knee out and shifting my weight forward to the inside when cornering is about as radical as I get.
Funny thing is that the Rice burning resin rocket riders who're climbing all over their machines don't actually seem to cornering any faster than me. 😏
I have got a full spare set of lightweight trackday plastics now and I'll probably fit just a foam rubber pad on that seat.
But as I've said on looonger trips the Corbin's very hard to beat in the comfort stakes.

On another subject Nessie's operations haven't turned out very well, the bones aren't fusing where they should, but are where they shouldn't!
She may need another 2 operations, the surgeon has said that it's probably going to meen that she'll never drive a manual car again.
If the next 2 ops' don't work it's probably going to meen amputation, not very good for a woman who's only going to be 39 on Sunday.
Fortunately it being her left foot, she'll still be able to ride the RH gearchange '74 250 Desmo, good job it's got a proper Brembo Disc front brake, although I'll probably change the caliper for a period AP Lockheed item using an adaptor plate.
So I better get my arse in gear.

Steve R

woodmanr

I'm the son of the owner of the bike (Walterr839, who just posted these pics again not realizing these were here). To answer a few of the questions. The forks are like DB said, custom built R&T's by Brad Miller of Motion Superbikes. We wanted to keep the 888 triples, so he combined a set of Suzuki upper and Ducati lower to make the forks. We had to then change the front axle and front fender for the 916 front wheel. The rear wheel is just a standard 5 spoke off a monster.

As for the seat, it was put on for a bit more comfort then the stock. My dad is no spring chicken any more, but still loves riding. Just had a bilateral knee replacement (both knees replaced) so he could get more comfortable on the bikes, and also not have pain when walking....

burtsp5

Rebuild...

Well done, it would be good to see what performance figures you get from the ol' girl without exploding the cases. Although mine will spin up the same mark, it very raley goes there, only having an odd ferrari chasing moment,(Stafford) so i'd careful there if i were you.
Its a shame you sliced off the rear mudguard, but i guess thats me being picky. As per Mr R, youre running no flywheel or are you using some sort of trigger disc arragment but then i guess she doesnt tick over too well?
Anyway, beautifully made Spaghetti system, who made that one? well done.
Enjoy riding it and a job well done.
Cheers.
Guy