We were Ducati/Norton Dealers in the 60's. When we uncrated 2 Mk3 350 Desmos. I was anxious to take the Rocker Arm Cover (5 allen Screws) off one of them to see if the upper/lower Rocker assembly was like the F3 Racing Desmo Head which uses a small helper spring attached to the Lower Rocker arm. This small spring just insures positive valve seating when the Closing Cam lobe lowers the Valve to the seat.Even with this small Spring you can open and close the Valves (head off) with your thumb and finger rotating the Cam Nut below the Triangular Cover on the right side of the head. I was shocked to see a set of Hairpin Springs just like the Non Desmo Models. I called Berliner Motors in N.J and talked with a Parts Man that I knew pretty well for years and asked why are they still using Valve Springs on a Desmodromic head. He said the factory did this to avoid any warranty issues with the Valve train and the Spring Pressure was what a 160 Head used. That still didn't make sense to me, because your defeating the whole purpose of Desmodromic Valve Actuation by still use Valve Springs which robs HP by the pressure needed to open valves. The most power robbing feature of a 4 stroke engine is opening the intake and exhaust valves and depending on Different Applications can be hundreds of lbs opening pressure. Long Story Short, We left the Street Desmos as from the Factory but on my own Street and Race Engines I did the heads like the F3 Race Engines and had no problems at all. Even running 10 grand + on my DT Race Engines, there was no problems at all. The Engine acceleration off a Corner was so noticable compared to a Non Desmo based Mk3 Engine. If you have an OEM MK3D 250/350 I without hesitation say get rid of those Hairpin VS's put the Helper Spring on the lower Rocker and see the difference in your Engine's Performance (BTW: This was using the Black MK3 Long Megaphone)
@nicksmith7552
Жыл бұрын
Thanks for the advice Steve.. I have a 1971 450 Mk3 non Desmo.
@martinburke362
Жыл бұрын
For its time the best little single ever made!! Back in the day a kid in our neighbourhood had i think it was a 175 Ducati single it had a square headlight, nobody on the 250s we all rode could get anywhere near him, he was off like a shot!!
@claudiomagi5375
Жыл бұрын
Bella moto!!!👏👏👏
@tonnyboer1332
7 жыл бұрын
My first bike was a 1970 Ducati Mark 3D. My first love. I wish I had one.
@earboy1
14 жыл бұрын
Great job.
@benignomartinez4583
Жыл бұрын
madre mía de este modelo solo conozco dos motos
@hawaiisidecar
4 жыл бұрын
Delicious!
@ianfluker5379
10 жыл бұрын
I had a 250 MkIII in 1971. I rode it to watch the Easter bike races at Bathurst. There, a suspicious knock developed in the engine so the Ducati came home in a trailer. I sold it for (I seem to remember) $100-00.
@jonesmike53
3 жыл бұрын
My tears are with you, brother. I rode my 500 Pantah up to Bathurst many times, but never the little Mk 3 - which I was forced to sell by my then girlfriend who funded the purchase and then renegged. In my case it was for maybe $300-$400. I really miss the little Duke, but I retained the 1981 Pantah and she's on historic plates now.
@helliottjr1
13 жыл бұрын
@veloce192 compession release lever operates a small plunger in the combustion chamber.
@johnburns3703
2 жыл бұрын
right leg!
@mervynjones1759
7 жыл бұрын
Always wanted a Ducati , as a pre -teen i used to salivate over the Ducati's in the ducati shop window @the top of Capel St , Dublin
@drucatic
10 жыл бұрын
Just like my first Ducati 350 Mark 3 Desmo.
@dorailzamacedo264
2 жыл бұрын
P
@pepindebielle227
10 жыл бұрын
" compession release lever operates a small plunger in the combustion chamber." Systeme similar and original on the 450 RT desmo.
@skiraf
11 жыл бұрын
how can the bike start without compression? (if the compression release is engaged?)
@jonesmike53
3 жыл бұрын
You release the compression, gently push the kick start till the piston reaches top dead centre (TDC), close the valve ... and kick.
@johnburns3703
2 жыл бұрын
I used to use my left leg to start my 350..and 250 and 200.
@johnburns3703
2 жыл бұрын
yes right leg is correct. jameas allan brogues were my footwear.
@veloce192
14 жыл бұрын
Nice, how does the compression release work if it is a desmo?
@frankoducati
6 жыл бұрын
Works on a different principle to the standard VALVE compressor which lets the air out .Its a decompression lever that is drilled and tapped into the combustion chamber wich lets the air out through a tube with a small valve in it ,the hand lever pulls the cable wich is attached to the tube and opens the valve in the combustion chamber and lets the air out.Have a look at a photo of a RT 450 and boule see the decompression fitting coming out the right hand side of the cylinder head,the racing boys would take the decompression fitting out and put a 10mm spark plug in and have a twin plug head!
@jonesmike53
3 жыл бұрын
@@frankoducati I had a 1968 Mk III 250 for a few months only - loved it and still would if I could afford one now. I didn't even know it had a decompression valve. But a 250 is a lot easier to kick than the notorious 450 Shotgun !
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