|
|
Paging Ducati experts
|
I'm not *quite* sure of the ST4 model history, I've seen a couple of
conflicting items.
In particular I'm probably thinking of an ST4S, am I right in thinking
this was always the 996 motor, with ohlins suspension, Marchenisi wheels
and brembo goldline brakes?
Did all "S" have ABS or was it optional.
Did the ST4 start out with the 916 engine then move up to the 996 around
(?) year 2000
My recollection is that doing the belts on the 996 engine was pretty
easy? making the only real service overhead the Desmo valve clearances.
|
Sorry to contradict Ant, who's rapidly becoming The Ducati Voice(tm)
here, but the original ST4 did indeed have the basic 916 engine. The S
got the 996.
As regards servicing, Ducati belts are easy to replace - tensioning
them properly is the crucial thing. As the engine gets hot it expands
and the belts tighten up. They've actually got to be set with the
recommended amount of slack, which can seem alarming on first
acquaintance.
This is why some people have had expensive blow-ups on Dukes. They
either set the belt tension too tight, so they strip the teeth or snap
as the engine warms up, or they set it correctly and hammer the thing
from cold, and the belt can jump a tooth on the pulley. Allegedly,
blipping the throttle heavily at cold (ie: to over 6k and then down
again) is the culprit here as the slack belt tension changes
dramatically power-on and power-off.
|
How is the tension set then? The setup on the Gilera bialbero motor is
|
There are a couple of ways to do it, but the best (IMO)
way is to use the correct guage. You simply clip this
at the correct point and depress the plunger. It reads
on a scale between too low and too high, so as long as
you're mid point then they are fine.
It really is easy to do - slacken off the tensioners
and off comes the belt. Put new belt on, tighten adjuster
slightly then tension adjust before doing everything up.
My mechanic did both in front of me in under 5 mins.
I've heard of people setting it by gap to a certain point
(which obviously depends on how hard you can push!)
and the official Ducati tool uses vibration measurement
to guage the tension.
I'm sure web-search will provide pretty pictures.
|
foolproof as long as it is done regularly. Just release the nut
holding the tensioner and a spring takes up the slack to the required
degree. Recommended to be done at a sensible (cold but not freezing)
temperature and give the tensioner a bit of a jiggle to make sure it
is moving freely though before nipping it up.
|
Inevitably, there's a Ducati special tool, although I understand
judicious use of a spring balance works, and exerienced mechanics can
do it by feel.
|
|
Best thing to do is just to let it warm up gently, and ride it gently
for at least 15 minutes before giving it stick.
|
Good advice on any rubber cam belt bike - particularly one not started
up for a while.
Fortunately the Gilera unit isn't quite as fussy or my hill climb warm
ups might have been a bit tricky.
Do they recommend a belt change on the basis of age as well as
|
Yes, they do. Most decent mechanics will check on the
yearly service for obvious signs of wear and will do
a feel to see if they are ok. Belts should be replaced
every 12k miles or 2 years, whichever is first.
We changed the belts on the 620 engine when it was
in for a quick check before the long race at Donington
in August last season, as it looked like a stone had
got into the belt housing and had worn about 1/3 of
the way across all of the teeth off and another lump
was sat inside a split in the belt. Mitch said they
were the worst belts he had ever seen on a running
bike.
The ones on the 748 sat in the same position from
Sept 2005 (Rockingham trackday) to October 06 (when
it finally got serviced) and they were well formed
into the shape of the belt run! Good job I took it
on the trailer. Mitch then updated his opinion that
these belts were the worst he had ever seen.
BTW, all Ducati belts are now made of kevlar.
|
mileage?
Some belts broke on Nordwests that had been stored in crates for two
or three years before being sold.
|
I dunno. IIRC, it's 12k miles for 4-valve and 8-valve engines, but
many people (including myself) change them at half that mileage, and I
think anyone who's smart changes them every two years irrespective of
mileage. They tend to harden a little bit if just left standing.
|
|
Valve clearances take quite a long time on the eight valve-twins.....
|
|
Dunno what's happened to the earlier web-search post, but Ant is wrong.
The original ST4 had the 916 engine and yes, the ST4S got the 996.
|
|
|