is my engine a 900SS or SD ?

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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wizzythecat
Cucciolo - the Lil Pup
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is my engine a 900SS or SD ?

Post by wizzythecat »

Can anyone help with an ID on this motor, Bit new to old Ducatis and this is for a new project, I have a 1980 (ish) 900 square case motor, 86mm bore, bosch ign, 40mm inlet, 32mm ex with PHM40 carbs, cyl head stud spacing is 52mm, no elec start, engine No is 902742DM860. Bit stuck on this as i have been given conflicting info. Any help would be greatly appreciated, Thanks
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Craig in France
Paso 906
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SS or SD engine

Post by Craig in France »

According to Ian Falloon, the DM860 90**** series is the designation for the electric start engine that was first used in the Darmah SD and later in the electric start S2s and MHRs. Kickstart only SSs & MHRs use a sequence that starts with a 0 (including 090**** which is where the confusion may have crept in).

You can see confirmation of this by looking at the database of numbers on Steve's site http://www.bevelheaven.com/index2.html > Technical info> Data index. Yours fits in as a SD engine from 78 (I know the owner of 902721, and his is a 78 ).

I suspect that was has happened is that a previous owner has replaced the original left side cover with a non-electric start one, probably after the sprag clutch failed.

Btw, 40mm carbs on the 52mm stud head is something that happened with some UK Darmahs in '78. Unfortunately, the inlet tracts weren't enlarged at the same time in order to deliver the greatest benefit :)

Ciao

Craig in UK
'79 SSD
wizzythecat
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Post by wizzythecat »

Thanks for that Craig, just checked out the numbers link you sent, all makes sense now. I don't suppose you know what else is required to bring the engine up to ss spec and the output as standard?
Thanks again, Chris :-D
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Craig in France
Paso 906
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Joined: Tue Mar 23, 2004 3:58 pm
Location: Montpellier, France

Post by Craig in France »

Hi Chris

I suggest it'd be worth you getting a copy of Ian Falloon's Ducati Twins Restoration Guide which gives a lot of detail about the various engine modifications. In general, the Darmah engine was an improvement on the SS engine, particularly as regards the big-end bearings and ignition, and all SS engines had the 'Darmah' improvements from 1978 onwards. So the performance difference between a standard Darmah engine and a standard SS one isn't perhaps all that legend might have you believe (particularly without the weight of the electric starter mechanism!)

Of course, the standard upgrade was fitting 40mm carbs (with the inlet tracts opened up!) and Contis. But the factory also did a range of racing kits including over-size valves, high lift cams and an oil cooler - all detailed in Ian's book.

And of course people like V2 have been developing and selling their own performance parts for years. Guess it's a question of how far do you want to go, remembering the age of these engines and the fact that any modern 600 is likely to blow you into the weeds anyways :-) (Woops! I know Steve Allen doesn't approve of me saying this!)

Ciao

Craig in UK
wizzythecat
Cucciolo - the Lil Pup
Posts: 3
Joined: Mon Feb 20, 2006 11:08 am
Location: bedfordshire

Post by wizzythecat »

Many thanks Craig, will do :-D
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