Duc threating to leave AMA Superbike

So do you think we should have stayed with 2-strokes in MGP?
They don't even have a valvetrain.

 

As a matter of fact yes but with more advanced technology (cleaning
burning & 400HP+ per liter). How? Direct High, not low pressure direct
in-cylinder fuel injection. Also, more revs can be gotten from a two
stroke by separating the crankcase input rotary port from the
crankcase at large. I've read articles of two strokes running up to
40K RPM. Also, a better baffling system to filter the crankcase oil
injection from up into the combustion chamber. Even Suzuki used
pressure feed main bearings back in the 70's on their 750 water
buffalo". Evenrude currently has a line of two strokes with lower
emissions than ANY 4 stroke. They have a very efficient system of oil
injection without compromising durability.

Hell you can even do various versions of closed crankcase two strokes.
One old example is the GM designed Detroit Diesel with a pressure feed
intake. Hint: that's where all those old dragster blowers originally
came from.

If you watch "Saving Private Ryan", you can hear the old 2 strokes
6/71 Diesels as they approach the beaches. Those engines were designed
in 1938 but there are many, many variations of two stoke (closed
crankcase engines). Look it up if you doubt.

BYW, ANYTIME you want to discuss engine designs in detail, don't
hesitate

Bob Nixon, Chandler AZ
01 Sprint ST "RED" 54K miles
http://bigrex.net/pictures

 

I think this is more than offset by the reduced friction in the valve
train. You can spin a Duc four valve cam by hand; try that with a
conventional springed head.

It's funny how Ducati critics are quick to point out the 6K valve check
interval, while BMW motorcycles enjoy this reputation for bulletproof
reliability. Valve maintenace interval on an oilhead? 6K.

In the Duc's case, the clearances on the closers are about .002 (+-
..001). The concern seems to be that if something does cause the
clearances to go out, it's not far until you get into negative
clearances, which would be very bad on a closer. This, by the way,
strikes me as a more significant disadvantage to the design than the
reciprocating mass of the extra rockers.

On the belts, I mostly agree. It's not so much that they're using
belts, it's that they can't make 'em last more than 11K miles. There
are plenty of reliable auto engines using belts and thoise belts are
under quite a bit more strain. The Duc's belts take such a convoluted
path that they wear much faster than they need to.

ab

 

Big Twin... big power... big mistake... what's Ducati thinking??? the
bigger the Twin the longer the cylinders and that means the heavy
crankshaft will rest further aft than it does now in the 999... mercy at
some point front end feel is going to suffer a rear weight bias...

Ducati has raced every new bike they have produce... it's in their
blood... so what's stopping them from marketing the Desmosedici V4 as
the next homologated WSB racer??? anyone???

I believe the Desmosedici V4's crankshaft rest 2.5 inches further forward
than the 999's V2 crankshaft... and a forward crank is paramount for
good front end feel... and a 1200 V2 is the wrong direction...

Larry L
94 RC45 #2
Have a wheelie NICE day...
Lean & Mean it in every corner of your life...
If it wasn't for us the fast lane would rust...
V4'S are music to the seat of my pants...
1952 De Havilland Chipmunk...
Yank and bank your brains loose...
http://members.ebay.com/aboutme/-xlax-/
http://home.comcast.net/~netters2/
http://www.fox302.com/index.pl?s=vg&user=netters2
http://www.reeky.org/gallery/xlax

 

This engineer realizes there are a 100 year history of Desmodromic valve
patenting in 6 different countries including the US... and according to
my 1910 Encyclopedia of Engineering the first patent was awarded to F.H.
Arnott on a English JAP motorcycle...

Ducati adopted the Desmodromic valve in 1957 so they could rev their 125 beyond
the 8,000 mark without worry of valve float... something the Japanese figured
how to with springs and broke the 8K barrier ultimately reaching the 20,000
rpms without worry of valve float...

Ducati is mired in tradition just like HD is mired in tradition... that's fine
but tradition is largely lost on the new generation of buyers...

Larry L
94 RC45 #2
Have a wheelie NICE day...
Lean & Mean it in every corner of your life...
If it wasn't for us the fast lane would rust...
V4'S are music to the seat of my pants...
1952 De Havilland Chipmunk...
Yank and bank your brains loose...
http://members.ebay.com/aboutme/-xlax-/
http://home.comcast.net/~netters2/
http://www.fox302.com/index.pl?s=vg&user=netters2
http://www.reeky.org/gallery/xlax

 

Actually, I usually get around to service at 12k intervals and EVERY
time I've had the things returned their condition was such that you
couldn't tell them apart from a brand new belt. Again, IMO more
commissionary reward for those dealers willing to carry their low
volume product.

 

Andy, you're being fooled by spring action. Valve springs give back
98+ % of what in takes to compress them minus the heating of the
spring steel. Same thing with an open throttle piston except there is
more loss of both heating of the air/fuel mixture or just air and
greater friction than a simple poppet valve. Believe me, the mass of
the vavle train is the most importiant thing at high RPM. Valve float
of springs these days is good for =>18,000RPM.


[...]
Bob Nixon, Chandler AZ
01 Sprint ST "RED" 54K miles
http://bigrex.net/pictures

 

Technical data please?. Just the numbers. The big valves and cam gear
on a twins only exacerbates the problem. Quote the RPM of a "works"
WSB 999 Ducati.

Narrow valve angles BS. Sprockets, smockets- Ever heard of putting a
chain around a single cam then drive the other cam with a gear to the
other, up top?

Aprilia 60 degree 1 liter engines used in WSB have NEVER been able to
eek out as much HP of the other thee twins (Duc, SuK & RC-51).

Twins are fast becoming an anachronism these days. They try too hard
to make them rev like a four and end up with other compromises like
huge bores and valves. Meanwhile the I4s are getting longer strokes
and getting away with it. Look the bore to stroke ratio of the
GSXR1000 compared to the RC-51, Rotax or Duc 1 liter engines.

Twins are dead. Triples and of course fours are the future. The inline
3 and 4's are much simpler and cheaper to mfg and can make more power
(smaller. lighter valve gear but relatively larger high RPM breathing
capacity). And the longer strokes null out the former advantage of
low-end grunt. Also big bang firing order nulls out the twins
advantages pulling out of turns. One last thing 3/4s also have greater
exhaust scavenging potential. And with power valves on most now they
don't have to sacrifice low-end grunt.


Bob Nixon, Chandler AZ
01 Sprint ST "RED" 54K miles
http://bigrex.net/pictures

 

Funny how my Duc is slowest in its class, lowest in BHP, slowest
top speed, slowest acceleration, and manages to have the lowest
elapsed time around the circuit (at places like Sears Point and
Laguna Seca).

No, I don't credit the weird valve train -- it's the chassis,
suspension, and grunt out of corners.