Wanted Ducati 250 Clutch

[DewCatTea-Bob]

[quote= Nick ... "
" Here's one, "

____ Isn't that the very-same "one" you posted before, (in your "Diana" thread) ?
To help make it a more-worthy difference, I'll add another version for you (showing the main-difference between it & a w-c.version).



" Strange that Dr. T. should have been worried about the cases- "

____ It wasn't so much the n-c.type cases them-SELVES, but rather more-so their capability of supporting larger main-bearings (for a beefier crankshaft), etc.


Dukaddy-DUKEs,
-Bob

[graeme]

Hi Nick, thanks for the picture. What's written on the tank? (edit, I read your post again sorry )
Looks very comfortable, but like a lot of bikes from the time, ugly as a hat full of arseholes.
I don't mean to condemn the Sebring as I would be proud to own one.

Bob, by using a shorter rod in a 450 will make more torque?
If so the vibrations may become worse?
Longer the rod the less vibrations? (according to Phil Irving)

Graeme

[DewCatTea-Bob]

[quote= graeme ...
" ugly as a hat full of arseholes. "

____ I must say that I don't agree... as that later-Monza/Sebring-tank is my 2nd.favorite Duke-tank, (and the only part I don't much care-for is the squarish-headlamp). _ And the rest of the Sebring seems to appear as nice as any other Duke-model.
After being used-to the appearance of pre-1966 models,, when I first saw the new 1966-models, I was then impressed with them appearing as 'MODERN' ! - (Pretty-much the same as when I was first-impressed by the 1964 Ford fastback-Mustang's modern-appearance.)



" by using a shorter rod in a 450 will make more torque? "

____ I wouldn't go so far as to claim that more total torque would become created,, but rather, simply more-concentrated & closer to being fully-peaked.
__ It's sort-of akin-to the situation of an L-twin with it's camshafts not being closely synchronized* for obtaining it's optimum 'max.torque', (* such as when both cylinders are both producing their peak-torque nearer-to the same-RPM, rather than spread-apart at different points) !
Longer con.rods spread further-apart the points in time when peak combustion-pressure & max.leverage occur. _ And that's also akin-to quickly-exhausting most-all of your might when attempting-to break-loose a seized-bolt BEFORE your grasp has reached the furthest-end of your breaker-bar,, when by-then, your already exhausted peak-strength has become too significantly reduced to do any better. _ So it's of-course MOST-advantageous to use all your might not before your hand-grasp has slid-down to reach the very tip-end of your breaker-bar.
Sorry that's the best common-example I've come-up with to analogize the 'timing' of matching-up the combustion peak-pressure & optimum-leverage points, (that varies depending-on con.rod-length).
In similar like-kind... at the very-beginning of the power-stroke (at TDC), the building pressure in the combustion-chamber is then trying to force the con.rod DIRECTLY-against the crank-pin which is then at zer0-degrees,, which while at THAT particular point, the combustion-pressure then CAN'T contribute ANY torque what-so-ever, since the 'leverage' is then at absolute-ZER0 (regardless of rod-length) ! _ FORTUNATELY however, THAT particular-point of the power-stroke is-not also the very-same point when MAXimum cyl.combustion-pressure occurs,, (but still undesirably,, the max.pressure-point unfortunately still occurs TOO-soon, for ANY rod-length to most- OPTIMALLY take advantage-of). _ As just as having the con.rod attempting to push-against the crank-pin whilst at 0-degrees, is totally-unproductive (at converting the pressure into torque),, conversely, having the rod pushing-against the pin whilst at a 'right-angle', MAXIMIZES the leverage-advantage ! _ And-so it's thus better for producing 'maximized-torque' by having that best possible leverage occur as soon as possible after cyl.combustion-pressure has peaked ! _ But unfortunately the longer the con.rod is, the later in time it thus takes for the rod to reach the optimum/right-angle against the pin, (when combustion-pressure has further fallen-off from peak),, thus-then 'max.leverage' is left to be combined-with reduced power-stroke pressure (compared to that which a shorter-rod gets combined-with) !
__ Hopefully at-least some-of the above explanation-attempt, helps-to clear-up how 'MAX.torque' is brought closer to 'peak', with a SHORTER-rod. ...
(Perhaps another pic.diagram will help !?)



" If so the vibrations may become worse?
Longer the rod the less vibrations? "

____ The n-c.350 does vibrate harder than the w-c.350, but I figure that's mostly because the ratio of reciprocating-mass to motor-mass is greater with the n-c.350.
I suppose the piston (along-with the rod's small-end) is forced to stop & start harder with the shorter-rod, thus cause more notable vibration,, but I'd also figure that a fair amount of the vibration trade-off would be partially-canceled because a shorter-rod is lighter (and-thus lesson the reciprocating-weight).
__ I've long had a 'short-rod' 450-project, which I haven't yet given-up on. _ But I haven't ever yet made a firm-decision on how-much to mill-off from the 450-cylinder's height.


Dukaddy-DUKEs,
Dct-Bob

[DanM]

Here's a picture of my 1965 Sebring 350 round tank.

[Nick]

Dan, very nice! That's beautiful. How could the same company get it so right (yours) and so wrong (mine)? Maybe like the British with their first Triples they brought in some 'experts' from the automotive world....

[DewCatTea-Bob]

[quote= Nick ...
" How could the same company get it so right (yours) and so wrong (mine)? "

____ Here's a link to a related thread on the topic... viewtopic.php?f=3&t=1066&p=7245&hilit=Honda+Dream#p7242
It seems it took too-long for Ducati to get-into production an Italian-designer's (cheapened)- version of a rather popular American 'Dream'.


Duke-Cheers,
-Bob

[Nick]

The Dream/Sebring connection is quite interesting. This is the first I've heard of it. Most people are unaware that the Dream's unique styling was Mr. Honda's attempt to create a motorcycle design based on traditional Japanese architecture. This was called the jinja-Bukkaku style. A Jinja is a shinto shrine (Japan's traditional religion) whereas Buddhism is the imported religion (from China). This influence can be seen in not only the square headlight nacelle, but in the sweeping front and rear fenders, the curves of which mimic the curves found on Shinto shrines and the roofs of Buddhist temples. Prior to the Dream, the styling of most Japanese motorcycles was highly derivitive, so Mr. Honda deserves kudos for attempting to create a uniquely Japanese style. How well he succeeded is open to debate..... as is the question about how well the Sebring competes....

As it happens I also own a 305 Dream (found in a junkyard) which I ride regularly. What I find most interesting are the many young people who comment on its stylishness, having no knowledge (or prejudice) regarding its origin, year model, etc. When the Dreams first appeared in the U.S., none of us would have been seen dead on one!

The Japanese / Chinese character on the side cover means 'dream'.

[DewCatTea-Bob]

[quote= Nick ... The Dream/Sebring connection is quite interesting. This is the first I've heard of it. "

____ Well even now Nick, I really don't think you've actually "heard of it"... as any such connection is pretty-much too distant to be given much serious consideration as a certain-connection (from the Dream to the Sebring).
What IS known is that after the 250/305 Dream-models became established as good sellers within the USA (between 1958 & 62),, Berliner was well aware, and by 1962 asked Ducati to design a model that would appeal to the same segment of the American-market (and hopefully hit-the-spot even more-so with still better-yet appealing-styling).
So a 300GT with such styling was hoped-for by 1963, but nothing the-like came-out until late-1965.
I'd say that for-sure it's MORE than likely that the style-designer of the 1966-GT/Monza/Sebring-models had certainly realized that his expected task was to come-up with a motorcycle-design that would 'out-appeal' the Honda-Dream, (but of-course would also likely never admit-to trying to 'copy' it at-all, in any way).
Back in 1966, there were at least two cycle-mags (one being CycleWorld) which had included comments about this possible connection.


" is open to debate..... as is the question about how well the Sebring competes.... "

____ I for-one, believe that Ducati had missed-the-mark and-thus mostly failed to compete for the target-market (for 1966).
However Honda chanced-upon a market of scooter-riders that wanted to 'graduate' towards REAL-motorcycles (with such scooter-hybrids).



" As it happens I also own a 305 Dream
What I find most interesting are the many young people who comment on its stylishness, "

____ I wonder what wording Graeme would come-up with to state HIS particular opinion of it ?



" When the Dreams first appeared in the U.S., none of us would have been seen dead on one! "

____ By: "us", I assume you must mean 'motorcyclists' !? _ As back-then real-motorcyclists thought of those HONDAs as 'scooters' (with larger motors too-big to hide).
Back at the time, I was a mere 'cyclist' -(bicycle-rider), and thusly saw those Dream-models as (funny-looking)- 'motorcycles' * (which were rather-obviously certainly intended mostly for female cycle-riders).
(* Which I had reasoned as being fully fair, because-of the obvious-difference in motor-location.)


Enlightening-Cheers,
-Bob

[graeme]

" As it happens I also own a 305 Dream
What I find most interesting are the many young people who comment on its stylishness, "

____ I wonder what wording Graeme would come-up with to state HIS particular opinion of it ?

Honda people have always been stylish,,,,,

[graeme]

Nick, I do like your Honda. And you should be proud of it and its styling.
I apologise for hanging shit on 2 of your bikes,
It was in jest. ( in case you think I am serious)
Any motorcycle is interesting to me, what ever brand or model.

Graeme