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Vincatii


Chris Launders

Well Known and Active Website User
VOC Member
The problem explained to me by Steve Wynne well known Ducati specialist (he built the ones Mike Hailwood rode in his comeback) was the oil recommended by Ducati, which was if I remember Duckham's 20w/50w which was (then) a modern oil for watercooled plain bearing engines and contained "long chain polymers" which wrapped around bearing surfaces, the Ducati being full of roller bearings and especially the helical cut bevels just cut these to nothing, resulting in stuff like water in a very short time and you would be lucky to get 15,000 miles out of a big end, whereas a monograde oil was more suitable and Castrol R about as good as you could get. I can't remember what mileage was on mine when I got it (1991) but it was stripped and changed to R40 as soon as I got it and I think now has around 50,000 miles on it
 
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Chrish

Well Known and Active Website User
VOC Member
The problem explained to me by Steve Wynne well known Ducati specialist (he built the ones Mike Hailwood rode in his comeback) was the oil recommended by Ducati, which was if I remember was Duckham's 20w/50w which was (then) a modern oil for watercooled plain bearing engines and contained "long chain polymers" which wrapped around bearing surfaces, the Ducati being full of roller bearings and especially the helical cut bevels just cut these to nothing, resulting in stuff like water in a very short time and you would be lucky to get 15,000 miles out of a big end, whereas a monograde oil was more suitable and Castrol R about as good as you could get. I can't remember what mileage was on mine when I got it (1991) but it was stripped and changed to R40 as soon as I got it and I think now has around 50,000 miles on it

If you are really interested i have a Vincati for sale in touring trim, and the way our Aussie Peso is going it could be cheap. PM me if interested.
 

Pushrod Twin

Well Known and Active Website User
VOC Member
Are you suggesting that I am not of sound mind?
The Honda donor frame was shaft drive. Thankfully it never crossed my mind to stuff the Comet motor in there sideways. That might have resulted in a VOC fatwa.
Yea, that's up there with me suggesting I fix my spare Auto Guzzi converter & 2 speed trans to the back of my other chopped Vincent motor, it did raise a comment or two.:D
 

Pushrod Twin

Well Known and Active Website User
VOC Member
Sadly, the horror stories above vindicate my thoughts regarding these bikes. While several of you have enjoyed riding them, the overriding message is still that they are unreliable. I expected by now to have a staunch supporter telling us how many they knew of that had 100 million miles, but no. I have been told by several owners that theirs had done an honest 100,000Km, or in one case miles, but there is only one 750 GT to which I give any credence to. That was a member of our VOCNZ section, recently passed away, but when I first got to know him in the Italian Motorcycle Owners Club in the '70s he rode his GT two up a lot, clocking up the the 100k until a Vauxhall Viva U turned in front of him & the Ducati tipped the Viva over. At that point John stripped the engine, and broke the lead seal on the crank case, while straightening the front end. He had run it on Shell high detergent multigrade diesel engine oil which debunks the international myth started by Steve Wynne about the absolute necessity for straight grade 50 weight.
The real problem with the cranks was pointed out to me by someone with a knowledge of metallurgy & is well demonstrated by Oexing's pic of the rod. In case you hadnt noticed, there is no sleeve inside the rod eye, the rod is hardened & ground like a two stroke rod. At the confluence of the shank & the eye is the largest mass of material. When that is quenched from red hot it is the area slowest to cool, hence slowest to harden. The hardening is likely to be be both softer & thinner. It is also the area of greatest load. It all goes down hill from there.
I have also been shown several of these power plants with failed gear shaft bearing areas. They run crowded rollers straight on the shafts, the rollers pick up the shaft hardening, simply overloaded bearing area. I have also experienced two with failed gearbox main shafts. One was brought to me for opinion prior to purchase. I only rode it long enough to drop it into top gear, at which point the concrete mixer noises started, I handed it back quickly & recommended a trailer! We had another do the same thing a couple of years ago at a National VOC Rally in Central Otago.
So that is enough of the bad news stories, the solution to getting these nice handling bikes back on the road is to track them down & fit Vincent motors. :D
 

Vincent Brake

Well Known and Active Website User
VOC Member
Are you suggesting that I am not of sound mind?
The Honda donor frame was shaft drive. Thankfully it never crossed my mind to stuff the Comet motor in there sideways. That might have resulted in a VOC fatwa.
And all you motorcycles obligatory end up in a raffle
 

Albervin

Well Known and Active Website User
VOC Member
Chris,
Well, there's an opportunity for you - probably the first person to be in a position to build a Ducvin or Ducent!
Simply(!) put the 860 Duke engine in a Vincent rolling chassis; probably paint the engine gloss-black first for even greater appeal. :cool:
Peter B
I have seen that done and it was not pretty.
 

Cyborg

Well Known and Active Website User
VOC Member
Yea, that's up there with me suggesting I fix my spare Auto Guzzi converter & 2 speed trans to the back of my other chopped Vincent motor, it did raise a comment or two.:D
Couldn’t think of a better way to neuter a Vincent twin. You should just do a mock-up and take a few photos. It would surely cause the rivet counters to foam at the mouth.
Probably said this before somewhere...I had both 750 GT and 750 S (round cases). Both very low k and only glitch was the S flung half of the tail light assembly into the ditch. I managed to part company with them both before any of the horrors manifested themselves. I worked at a Ducati dealership until I finally came to my senses. Some of the images are still burned into my memory banks. Have to say I did love how those bikes handled which seems weird to me now. Maybe it was just relative to other bikes of the day. They had a long wheelbase by today’s sport bike standards. Gives me hope for the Comet as it ended up longer than planned.
 

oexing

Well Known and Active Website User
VOC Member
Basically this is no Ducati forum but even so I´d like to share my feelings about some problem spots: Oil quality is most likely not the biggest factor in roller big ends, though high viscosity helps a bit, in gear boxes too. But then warming up the engine is critical and no high speeds while cold are recommended, with single grade even more so.
Hardness of Duc conrod and crank pin are to specs , most Japanese singles got same type of conrods case hardened, be it SR 500, Honda radial four valve types etc. . A pressed in bearing race does nothing for ruggedness of the big end so I made my own conrods from chrome-nickel case hardening steel like these too. BUT big factor seems to be the bypass oil filter with the 860 and 900 cc Ducs so when dirt goes through the roller bearings in there all faces in conrod and crank pin will develop tiny surface defects that get worse in use and fail in 30 000km intervals . Later types had pins from 36 mm go to 38 mm and I believe the oil filter was changed to full flow, cannot tell. Even later types and all belt types got plain bearing cranks to cure this trouble spot - but got other worries - well, Ducati all the way.
Don´t know about crowded needle bearing in Duc gearboxes, basically this is a very high load design and used in many car gearboxes too. I was thinking the stuck 4th gear my friend Max had in Finland was due to running a steel gear on a steel shaft direct, no bushes there. But then, same type in Vincent gearboxes, needs decent clearance I suppose ? A good idea is to fit drain plugs with neodym magnets in all suitable places, takes out amazing wear deposits at no cost - and is a diagnose feature as well.

Vic
home made Vincent conrods with INA 40-48-20 mm bearing
P1050474.JPG
 

Pushrod Twin

Well Known and Active Website User
VOC Member
If you are really interested i have a Vincati for sale in touring trim, and the way our Aussie Peso is going it could be cheap. PM me if interested.
Nice offer Chris, do you have to remove all of the asbestos components to export it as you would if you imported it? We feel it's only fair that under the International Asbestos Trading Agreement that Australia keeps it's share of the asbestos which it mined and kept in country seeing as it no longer accepts returns on asbestos it exported around the world for so many years. :p
Now, political pith taking aside, how would you like to give us some technical detail, please?
I would like to know how the rear of the engine fits into the frame, has the swing arm been connected to the rear of the crankcases?
 

Pushrod Twin

Well Known and Active Website User
VOC Member
They had a long wheelbase by today’s sport bike standards. Gives me hope for the Comet as it ended up longer than planned.
Comet ended up longer that planned; Longer in the wheel base, or longer to build?

One of he likable traits of the Bevel Ducatis, I feel, was their ability to be ridden with relative comfort on a gravel road. My mate Roger, & I rode around the East Cape together, he on an Australian export 860GTE, & I on the 850GT Guzzi I had bought off Roger a year earlier. When we turned into the gravel road leading to the light house, he took off, leaving me wallowing literally in his dust. Both Loop & short Tonti Frame Guzzi have always un-nerved me in the gravel. I guess I was spoiled learning to ride on AMC Jampot frames.
 

Oldhaven

Well Known and Active Website User
VOC Member
I really agree with that about off road capability with a bevel Duc. This is a picture of me 10 miles off the main road on a weekend fly fishing trip with my wife and another couple on the Dead River in Maine. The road in was used by a lumber company working in there at the time and was not your average gravel road. It was like a trials course. At the end of the trip the result was a slight crack in the bottom of the crankcase from hitting a rock. A bit of Seal All smeared on and it never leaked again for years. You can find Dead River Maine on Google Earth and see that they are still cutting trees all these years later

Ducati.jpg
 

Little Honda

Well Known and Active Website User
VOC Member
Who mentioned Comet, it looks wide enough for a twin !! and what person of sound mind would ride a Vincent anyway. That certainly doesn't describe me.
That Monster frame would do to put my spare bevel drive engine in, but the shipping is probably more than the frame's worth.
What about yr spare bevel engine? Wld swap it for a couple of nos Black Lightning valve springs plus spark
plugs! Free postage.
 

peter holmes

Well Known and Active Website User
VOC Member
In a moment of madness I purchased a Ducati 750S, it was advertised locally to me, and the chap was also selling a BSA Gold Star, at the time (approx 20 years ago) both bikes were similar money, a road test was out of the question, but I was allowed to ride it up and down his not inconsiderable driveway a couple of times, I loved it, especially its looks, and it ran really well, so I parted with my money and made arrangements to ride it home, Fawley to Bourne End, not that far at all, after a short distance I knew I had made a dreadful mistake, very uncomfortable riding position, wrists killing me, certainly would not want to do more than 50 miles on one, at that time 250 miles on the Vincent was easy, in fact a pleasure, and still is.
I kept it for a few years, my Son loved riding it in between riding various Kawasaki ZXR bikes that he owned, he reckoned that it went very well and of course always drew a crowd, but it had to go, it was no good to me, I sold it on for what I paid for it, maybe a little more, I forget now, but since then the values have rocketed, as a financial investment I really should have kept it in mothballs, or purchased the Gold Star instead,
c'est la vie.
 

Cyborg

Well Known and Active Website User
VOC Member
Comet ended up longer that planned; Longer in the wheel base, or longer to build?

One of he likable traits of the Bevel Ducatis, I feel, was their ability to be ridden with relative comfort on a gravel road.
Both.... it’s been a long time in the making. Not just adapting oddball parts, but also spending lots of time making parts and then... although happy with the way the part turned out, it looks out of place when installed.
Longer wheelbase than planned because the initial swingarm was shorter. It was made for eccentric adjusters and all was going well until I had a brain fart. Everything was strapped into the jig for a test fit and things lined up quite nicely so figured why not just go ahead and weld it. If I had been thinking, I would have welded it in stages. As one would expect the area that holds the eccentric adjusters warped slightly. That wouldn’t have been an issue if I had welded the arms separately. Then it would be a simple matter of bolting the arm into the mill and correcting the out of round. The welded assembly is to large to fit in the mill. I suppose it could be attached to the carriage of the lathe and bored that way. Things were dragging on so I grabbed a 650 BMW swingarm out of the dumpster and used that. It needed machining and welding, but was a quick fix. The Comet is still shorter than the V11, so should be fine.
The other thing I found with the GT and 750S is that they seemed to be very forgiving. You could screw up steaming into a corner and make corrections that would cause other bikes of the era to try and spit you off.
 

Pushrod Twin

Well Known and Active Website User
VOC Member
It was made for eccentric adjusters and all was going well until I had a brain fart. Everything was strapped into the jig for a test fit and things lined up quite nicely so figured why not just go ahead and weld it. If I had been thinking, I would have welded it in stages. As one would expect the area that holds the eccentric adjusters warped slightly. That wouldn’t have been an issue if I had welded the arms separately. Then it would be a simple matter of bolting the arm into the mill and correcting the out of round. The welded assembly is to large to fit in the mill. I suppose it could be attached to the carriage of the lathe and bored that way. Things were dragging on so I grabbed a 650 BMW swingarm out of the dumpster and used that. It needed machining and welding, but was a quick fix. The Comet is still shorter than the V11, so should be fine.
The other thing I found with the GT and 750S is that they seemed to be very forgiving. You could screw up steaming into a corner and make corrections that would cause other bikes of the era to try and spit you off.
Eccentric adjusters, I love them. Except on 860 & Darmah Ducatii where they are mounted at the front of the swing arm, what were they thinking?? I have a swing arm design drawn up with eccentric adjusters for my next Egli project. Good call regarding machining the bores before welding the legs, it is difficult to ensure alignment in a small mill unless you have a guaranteed method of maintaining squareness to the swing arm pivot. I have a right angle spindle adaptor for my Kondia, (Spanish Bridgeport copy) which allows me to set the boring head horizontal, could set the swing arm bore in clamped vee blocks and flip it between operations, maybe.
How is your V11 on gravel roads?
 

Cyborg

Well Known and Active Website User
VOC Member
Haven’t had very much exposure to gravel with the V11. I now live in an area where it’s very uncommon. That little bit of gravel riding tells me to avoid it. The V11 is a bit of a pig to pick up.
 

MartynG

Well Known and Active Website User
VOC Member
Haven’t had very much exposure to gravel with the V11. I now live in an area where it’s very uncommon. That little bit of gravel riding tells me to avoid it. The V11 is a bit of a pig to pick up.
Had a 'modern' V7 for a while. It was easy to pick up - good thing as the geometry was all over the place and in slow corners it would constantly be falling on its side .
 

Pushrod Twin

Well Known and Active Website User
VOC Member
Haven’t had very much exposure to gravel with the V11. I now live in an area where it’s very uncommon. That little bit of gravel riding tells me to avoid it. The V11 is a bit of a pig to pick up.
Yes, I had the use of a new V11 a while ago, stayed away from gravel. I also had a 4 valve Daytona Racing for a short time, they were both recipes for licence donation! I'm happier with my '72 V7 Sport and 2 Lemonverts. One started out as a MK IV Lemans, the Square engine now drives the torque converter & 2 speed in a Convert chassis registered as a LM II. Shortly that power plant will return to the 16" wheeled frame & become my sidecar tug. The "original" roundbarrel will be built as a 950 with LM II heads and return to it's LM registered Convert frame. Keeping up?
 

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