This is
Richard Elder’s 900ss
Richard decided to restore his 900 superlight and I was given the task, on recommendation of building a smoother more powerful engine in a
cost effective way making the most of all the standard engine
components.
I
decided a full engine blueprint would be in order with a fine balanced
crank and flywheel assembly matched to its new high compression JE
pistons. I don’t normally recommend the use of off the shelf JE pistons in a Ducati
and this has nothing to do with quality reasons. The 900ss piston being an exception
fitting the chamber , small end and piston pockets correctly .
The
fine balanced crank reduces stress on the main bearings and allows a
safer higher rpm limit.
The
cylinder heads received a full flow bench work over making the port a
more efficient shape without enlarging the ports main cross section
which if improperly sized can kill power. The standard valves were
kept but modified , polished and the valve seat angles were changed .
These cylinder heads now flow strong air above 9mm of valve lift which
is approximately the cut off point of the standard heads with a much
improved airspeed.
Ports before
Ports after
After
the heads were fitted and squish adjusted by using thinner base
gaskets the standard cams were degree'd to specs.
Richard had Tim at Motovation fit the engine and restore the bike.
The bike was run in and taken to Race Developments for a dyno tune
. It delivered a healthy 88 BHP which peaked on one run at 89.5hp
I'm
pleased with the result seeing that the bike is still only a 900 with
standard valves and long manifolds. This leads me to guestimate a
proper porting job on standard valves is worth 6 plus hp on a long
manifold carby engine. Easily
more (see bennos project ) if the powerband could be extended with short Malossi manifolds
and cams.
So far the result is a very strong , well balanced and cost
effective engine with an added 13 hp over stock ! .
I
thank Richard for giving me the opportunity to work on this bike and
make this article possible.
