Food for thought

creative words or images - your own or by others - that express for you the feeling of motorcycling
Post Reply
User avatar
higgy
paso grand pooh-bah
Posts: 3327
Joined: Tue Jul 29, 2008 9:50 pm
model: 907 I.E.
year: 1992
Location: Hilltown,Pennsylvania
Contact:

Food for thought

Post by higgy »

Maybe off the wall but I had to ask
Anyone know what is involved mechanically in fitting 851 heads on a 906/907 lower end ?
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
User avatar
Derek
paso grand pooh-bah
Posts: 768
Joined: Thu Nov 03, 2011 10:13 am
model: 907 I.E.
year: 1994
Location: Scotland

Re: Food for thought

Post by Derek »

Apart from the 2mm longer stroke on the 906/907 it should go straight on. It would need 2mm thick plates under the barrels to stop the pistons hitting the heads.
1994 907ie
2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL (now sold)


Scotland
User avatar
paso750
paso grand pooh-bah
Posts: 5558
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: Food for thought

Post by paso750 »

I doubt it`ll work. The 851 piston is 94 vs 92mm on the 907ie. The heads as the cylinders of a 851 are square shaped, the cylinder is flat with no projecting cylinder wall and uses a head gasket. While the stud hole distance should be the same also the oil and water channels have different shape & size.

G.
Speedmade
Posts: 50
Joined: Sun Jul 12, 2009 1:56 am
model: 906 Paso
year: 1989
Location: Minnesota, USA

Re: Food for thought

Post by Speedmade »

You would need the 851 (92x64) cylinders, pistons, and heads. As mentioned above, you would need 2mm spacers beneath the cylinders to deal with the 68mm stroke. One problem with using spacers that thick is the 4V belts get very tight.

In the past I have used 916 pistons (94mm) with 888 (or 916) cylinders (94mm), but the 916 pistons have the pin height moved to accommodate a 66mm stroke. Then I only had to use a 1mm base gasket to achieve the same goal. But less stress on the belts. And you can buy those base gaskets from Ducati, no special plate required.
User avatar
paso750
paso grand pooh-bah
Posts: 5558
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: Food for thought

Post by paso750 »

Right, the 94mm are the 851SP/888 models not the Strada. :zip:
User avatar
higgy
paso grand pooh-bah
Posts: 3327
Joined: Tue Jul 29, 2008 9:50 pm
model: 907 I.E.
year: 1992
Location: Hilltown,Pennsylvania
Contact:

Re: Food for thought

Post by higgy »

What about the frame fit, they look to be much larger than the stock heads
Reason I'm asking I ran across a great deal on a complete set of heads from a low mileage bike
Might pick them up any way just to add them to my stock for the future
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
User avatar
paso750
paso grand pooh-bah
Posts: 5558
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: Food for thought

Post by paso750 »

this is a complete 888 engine. (I wonder if the lower side of the tank had to be modified)
Image
Image
Image
Image
Image
User avatar
JoKing
Posts: 362
Joined: Mon Jun 20, 2005 12:00 am
model: 750 Paso
year: 1992
Location: Northern Germany / Kiel

Re: Food for thought

Post by JoKing »

Definately. And with 17 inch wheels, there would be a clash between the front wheel & the oil cooler/cylinder head when the fork is fully compressed. (At least with the 996-Engine)
92` Ducati 907 i.e. - ST3-Conversion --> Burned down with my barn
78` Ducati 900 SS - Bevel --> Sved her by risking my life
90` Cagiva Freccia C12R - Paso`s smaller sister --> Burned down with my barn
86` Ducati 750 Paso
96` Cagiva 750 AC Elefant
Post Reply