What bike did this engine come from?

If you need technical information or help with your BOSCH ignition squarecase Ducati 900SS - Darmah engine - post your FAQs, comments & questions here.
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Colin Linz
Diana
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What bike did this engine come from?

Post by Colin Linz » Tue Jun 22, 2004 2:16 pm

I have a square case 900 with Bosch ignition and desmo heads. I was going to use it as parts for my 900GTS, but have now been thinking of building a special based on it. One thing that I’m not sure about is the desmo heads with 30 mm Dellorto’s on them. I have heard of small port desmo heads and was wondering if this could be one of them? Does anyone know what model bike the engine could have come from?
Cheers
Colin Linz

Nico Georgeoglou
Cucciolo - the Lil Pup
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What bike did this engine come from?

Post by Nico Georgeoglou » Wed Jun 30, 2004 1:55 am

Hello Colin,

Bosch ingnition desmo engines with 32 mm Dell'Ortos (not 30 as you state) were go-slower versions of bikes produced with 40 mm Dell'Ortos. Ducati did this in order to pass ever stricter European noise and emission controls. Usually all these bikes were combined with quite (and ugly) Lafranconi silencers.
To my knowledge this "habbit" of using smaller carbs went on from 1978 to 1980, may be for longer period too.
Both my 1978 black/gold 900SS and metallic light blue 900 Darmah SSD are featuring this kind of small ports and 32 mm carbs, in combination with fully enclosed air filters and Lafranconi silencers. Lafranconis are scraped a long time ago, being replaced by loud Contis, but I have kept the 32mm carbs and filters in place for reasons of originality.
In this form bikes are lacking somewhat at top speed, but are much more willing and torquey at low rpm.
Darmah SD also used the same configuration, however for your info all versions of MHR (1978-1985) used only 40mm carbs.
Most people in Europe were porting these bikes immediately after purchase and were fitting 40mm carbs, thus making 32 mm carb bikes a rarity today.
I hope I have replied your question adequately.

Happy riding

Nico

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Colin Linz
Diana
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Post by Colin Linz » Wed Jun 30, 2004 4:03 am

Thanks for the reply Nico. I’m aware of the 32mm – 40mm options, as my bike has the 32mm Dellorto’s; however I have another engine that is a desmo headed 860/900 with bosh ignition that runs 30mm Dellorto’s. I’m now curious as to what engines, if any used the 30mm carburettors. Perhaps they have been replaced at one time, although I can’t think why you would do this.
Cheers
Colin Linz

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