The
following compilation of technical material is provided as a supplement to the
resources still available to the Ducati single cylinder motorcycle owner.
The material presented here is specific to Ducati single-cylinder motorcycles.
The information covers both narrow-case and wide case Ducati engines, and hopes
to cover many single-cylinder Ducati models.
Motoscrubs.com and its contributors make efforts to ensure the accuracy of the
information published on this website. However, the documents and web pages on
this site may contain technical inaccuracies or typographical errors. All such
documents and web pages are provided "as is.” Motoscrubs.com and its
contributors do not warrant the accuracy or reliability of the information
presented within, and will not be liable for any errors, omissions, or any
losses, injuries, or damages arising from its display or use.
Any information about products, services or merchants is provided for
informational purposes only.
Ducati ® is a registered trademark and is owned by Ducati Motor Holding S.p.A.
Motoscrubs.com is not affiliated with Ducati S.p.A.
Parts Books and
Manuals...
Thanks to a valued Forum member who digitized
all the following books for this website.

The parts books and manuals are presented
using the Cooliris©
media browser.
In order to achieve the full benefit of
the Cooliris© Wall, right-click your mouse and choose "Full Screen" to facilitate
parts book navigation.
A large screen helps...
450 Owner's Manual
...in PDF format
350 Scrambler Owner's
manual ...in PDF Format
Scrambler 250
Monza 250 Owner's manual ...in PDF Format
Diana Brochure
Ducati Singles Engines...

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Blueprint for Power
Herb Hitch and Jim Hayes Junior's performance modifications for the 250 narrowcase engine. |
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Narrowcase 250
Engine housing bearings chart |
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Instructions for Use and Maintenance of the [Ducati] 250cc OHC Racing
Motorcycles
Presumably written for the 250SC (narrowcase) racing engine, but of unknown
origin. |
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How to Build a Vintage Ducati Racing
Single
Engine, carbs, frame + more. Outstanding reference site - build-you-own rear sets, brake stays, etc.
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How to Repair a Slipping Narrowcase Kick Start Lever
Been there, done it... |
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Crank End float comments from Bevel Head DSM:
I've been working on the Mach 1 engine. I managed to find
FAG German made 'old stock' bearings (except for one) by shopping around. The
old bearings came out at about 250 deg F in the convection oven save one which
needed some persuasion. After cooling, I cleaned the bearing bores
carefully & reheated. The frozen bearings dropped in easily, but I found the
difficult one to come out did not spin easily when cool. It appears the
greater 'interference fit' on this one was also compressing the bearing and
pushing the outer and inner races closer. When the case was hot it spun
freely, but when cold it was binding. I had another bearing which worked. It
is possible the bore was not as clean as it should of been.
I made a case mounted bracket for my dial gauge for the end float measurement,
then put some rubber fuel line on my big screwdriver and was able to gently
lever the crank via the cylinder hole (the rubber bearing on the aluminum
case). The calculation did not work the first time, and I had to increase shim
thickness a few times. The gasket measures about .010" I've got some worries
that when I torque all the screws down to spec, it will compress a bit. So
far, I have just snugged down the screws. The crank turns freely but zero
float.
It did occur to me that since Ducati specs the end float at .001" to .002"
(the standard main bearings are not made for axial loads). the end float will
be taken out when the lower bevel gears are shimmed and meshed...which may not
be too good for them! Any backlash at all in the gears (there has to be a
little) will allow crank axial movement. I'm wondering if an improvement could
be made by using 15 degree angular bearings like the twin motors. Then end
float will never exist if the proper preload is applied...or at least not
until a lot of bearing wear.
Frank Scurria added this:
--- On Thu, 1/7/10, dsm wrote:
The calculation did not work the first time, and I had to increase shim
thickness a few times. The gasket measures about .010" I've got some worries
that when I torque all the screws down to spec, it will compress a bit. So
far, I have just snugged down the screws. The crank turns freely but zero
float.
*************
That's what I prefer---zero end float, but with the gasket compressed (which
it will do). Put a light smear of oil on the cases so the gasket won't stick
and tighten the fasteners the way they will be when the engine is running.
Please don't use any silicone sealer. In my opinion, it has no place on a
Ducati. If a "hatchet mechanic" has previously levered the cases apart with a
screwdriver, and marked the cases and some type of sealer is needed, I
recommend Hylomar, or Wurth (Hylomar made in Germany).
*************************************
It did occur to me that since Ducati specs the end float at .001" to .002"
(the standard main bearings are not made for axial loads). the end float will
be taken out when the lower bevel gears are shimmed and meshed...which may not
be too good for them!
**************
Definitely do not use bevel gear shimming to take out crankshaft end float.
Set crank end float first. That must be done separately. Then the bevels.
****************************************
Any backlash at all in the gears (there has to be a little) will allow
crank axial movement. I'm wondering if an improvement could be made by using
15 degree angular bearings like the twin motors. Then end float will never
exist if the proper preload is applied...or at least not until a lot of
bearing wear.
**************
I never tried that. I don't see the advantage.
Frank
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Ducati Engine torque
values from Master Mechanic/Author Tom Bailey: |
Torque
specification is described in the workshop manual as --"Tight".. (Smile) I
note that in attending 4 Berliner Ducati schools, all of which were about as
half ass as the one described in the book, at no point were torque
specifications ever discussed. Further in observing mechanics both at our shop
and at the races, I never saw anyone using a torque wrench in the assembly of
a Ducati engine, nor did I ever use one...
Interesting in that torque wrenches were religiously used in the assembly of
English engines...
I do not think the stretch factor ( which is the reason torque specs are
usually given) is critical with regards to joining Ducati cases. The 2 M8
bolts are there to stabilize the case for the cylinder head bolts and the M6
allen heads are there to provide oil tightness. You would think the cylinder
head bolts would be somewhat critical and have a torque rating but they are
likewise specified as "Tight". Perhaps the aluminum construction of all the
pieces (save the cylinder) provides enough expansion that it is not a
problem...
Torque ratings on M8 8.0 bolts (as used on the 160 - 350 narrow cases) are in
the area of 17 to 18 ft. pounds. I would think 10 percent less would be
adequate... Torque ratings on M8 10.0 bolts ( Widecase engines) are in the
area of 25 ft. lbs. - Again at least 10 percent less if I were doing it with a
torque wrench...
Stainless steel bolts (often used in modern restos) are weaker than high
carbon steel and available in a wide variety of different alloys of different
strengths. To find a torque spec for those you weed need to know the alloy...
As far as the M6 allen heads -- use a two inch long allen wrench and do not
overdo it. Strip the treads on the bottom of the oil pan and oil will leak out
the screw hole! We always coated the center gasket with olive oil. When beads
of oil oozed out of the center seam we figured it was tight.
One thing you do NOT want to do is use the screws and bolts to bring the cases
together - this will warp the cases. With a wood mallet and a soft wood rod
tap the cases until they are in contact, then put the screws in... Use an X
pattern for tightening the allen heads. Put the M8's in last.
In other words -- I don't know...and I continue learning that I don't know
more everyday.
Ducati Service Bulletin
The following service bulletins are
thanks to Ventodue:
And some more service bulletins donated:
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