Sigma Performance — Ducati 748-853

2 Май 2015 | Author: | Комментарии к записи Sigma Performance — Ducati 748-853 отключены
Ducati 1000 S 2

Ducati 853 Bip — The best Ducati never made?

The Desmo Quattro was a 748, it was an 4 valve racer used at the B ol in 1986 and the 4 valve heads built onto the then top of the 750 F1 Pantah crankcases.

Ducati had given the budget to take on the by the company’s new owners the Castiglioni’s. help from Cosworth, Bordi updated the 4V Desmodromic he had prepared as a student at Bologna and set to work.

The valves were small and, to get the Desmodromic in between the valves, the valve was not as flat as Cosworth would liked (an included angle of 40 rather than a sub 30-degree that could have achieved with valve Ducati wanted to stick their preferred Desmo and decided the sacrifice was worth it. The and … were the same as the F1 engine; 88mm bore and mm ….

During the road development stronger crankcases designed and the engine grew the 851 (92 x 64 mm) being the first engine The valves were unchanged the prototype and were still to fit over an 88mm bore As the road bike range got the engines grew in size, to 888, (with 94mm then 916cc, by taking the up to 66 mm.

Apart from increased sizes, the head remained (as say in the song) the same.

Once the 916 was established Ducati wanted a sports bike; not as one would just to compete in another category, but also to allow a experience to the owners, this was to be an that thrived on revs, and radical compared to the 916’s like torque. The bike with slightly lighter and a closer ratio gearbox same one found in the 996SPS

The market dictated that it be sold for less than a and although I have taken many of both models I have not worked out why it is any cheaper to a 748 than a 916 (or a 996 for that matter) as from bore and … are identical. This leaves us in the position of having many out on the street that can be best upon as shrunken 916’s, overbuilt in terms of strength.

The 748 has historically had several different The basic is the 748 Biposto, then was the 748 SP and SPS. Since 2000 the replaced the SPS (if you want more in info on these bikes a look at our articles on the 748SPS and 748R here ). The same engine also comes in the 748 (in the States) and the economy 748S and 748 models.

The engine has a wonderful free quality and makes superb both from under the and through the pipes because of the

If there is a problem it is that the is very near to the long reliability limit for the desmo operating the valves. Most owners do not get any problems, but by the time you the redline of 11500 rpm being hit regularly (you will do this by going flat out on a or blitzing round racetrack) will need servicing than every 6000 to keep them reliable.

All of our is designed to maximise (optimise is the right word) the power potential of the parts that built in the first place. We try to that an average owner is not in the 200 mile valve jobs keeping a full on racer a 748 RS ‘on track and competitive’

The 748 Biposto makes our job easier; as we pointed out above there is no difference between a 748 and a 916 apart the bits that are affected by the and … changes. In a perfect you would want to keep the effervescent, nature most wanted when they the bike, you would also to give it a bit more grunt out of the and allow the usual speeds a little less stress on the gear. If you could do this any compromise in reliability you would the best bike Ducati built.

The Best Bike Ducati built.

Steve Bennett into us at a track day at Silverstone. He had a 748 Bip at but was getting a bit annoyed at how hard he had to to keep up with his friends new 1000 four’ toys and he to do something about it, his bike was ready for its next service.

We the alternatives, a new 748R looked but the trade in would be punishing. a hand 748SPS would be but the power delivery would be a bit too for the road use he had in mind. Very he did not want the chuggy nature of a 996 he really wanted to keep the revving nature of the 748.

We that we could do our normal Monty service and while we at it we could do a little work on the and fit some special 94mm we had sitting around, this bring the capacity up to 853cc. The 748 is very receptive to this mod as the are the same as those used on the right down to the cylinder spacing and the size of the holes in the for the cylinder spigots; indeed the OD of a on a 748 and a 916 is the same.

The 94mm pistons we use have sealing Japanese rings like the latest 996R) and exactly the same as the standard 88mm pistons, this that we can go up to 853cc without any in reciprocating weight and therefore we need to lower the redline. To this in perspective the standard weigh 462 grams, including (piston) pin, rings and The GioCaMoto piston sold as a Performance accessory weighs 520grams.

Ducati 1000 S 2

Using these would cause a major in vibration unless the crank was to suit, even then anything like the standard would greatly increase the of a connecting rod breaking, and believe me you wouldn’t want to see what does to your engine!

The benefits of the increase in bore is the unmasking of the valves (same valves are in the 748 as the 916), these their flow restricted by the wall on the smaller 88mm engine. Our head modifications the head does not interfere low lift flow either. The 748 chamber is slightly smaller a 916’s and although we remove to ease the inlet valves ability we end up with a slightly compression ratio.

Engine building is a balancing of the effects working on the engine, compression equals good mid engine acceleration, too much the top end power, Squish is the same, as is timing. You have to build in the amount of each ingredient but not to overdo any of them. The nice about this engine and cam is the way the power hangs on once it just like the combination in a

This is very different to the high peak built a 748SPS.

We believe the compression to be 12 to 1; up from the 11.5 to 1 claimed by the for the standard engine. Obviously to get the power we use a revised Eprom relevant mapping to suit the capacity.

Once the engine is you therefore have a 94mm by 61.5mm … engine 853cc this gives an perfect 1.53:1 bore to ratio and a similarly perfect rod to ratio of 2.01:1. Compare figures to the new 996R Testastretta 1.57 to 1 bore to … and to 1 rod to …. The engine can breathe efficiently and the reciprocating weight is the as the standard 748.

None of the modifications are obvious the outside, the only clue a slightly more basso to the exhaust note.

The attached tell the story (click on the for a big version), Dyno run .004 is the run 85.4 hp at 9000 rpm and a peak of hp at 10800 rpm. R382RNL.010 is a 748 Biposto on which we had just a Full Monty service. run .008 is Steve Bennett’s 853 it had completed a 700 mile break in.

hp at 9000 rpm but with only a 2 hp in the next 2000 rpm, is really useable effective

The torque curves show an impressive increase with an of over 20% all the way through the range.

Ducati 1000 S 2
Ducati 1000 S 2
Ducati 1000 S 2


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