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For those who have a perverse interest in engine oil, there is an interesting article by Brook Henry about the subject on the Vee Two web site. Interestingly, Brook wonders why Laverda big-ends are bullet-proof and Ducati ones are not? I have often mused upon the fact that Kawasaki Z1 -Z1000 big-ends were known to be dead reliable, even though they had 250cc cylinders.

Brook does not recommend high-output oil pumps, and opines that they could actually harm the big-end. I have never understood the need to use higher output pumps, as all a roller bearing needs is a supply of oil, after-all, ball and roller bearings usually survive perfectly well with just a coating of grease. I suppose that it could be argued that pushing more oil through the bearing helps cooling. I would like to ask Brook about legendary Harley tuner C. R. Axtell's discovery that Ducati big-ends fail because the oil does not return to the sump fast enough.

Colin

Duccout wrote: Interestingly, Brook wonders why Laverda big-ends are bullet-proof and Ducati ones are not?

Quality of assembly was certainly one issue, Colin ...

Duccout wrote:I would like to ask Brook about legendary Harley tuner C. R. Axtell's discovery that Ducati big-ends fail because the oil does not return to the sump fast enough.

Indeed ... (even if Axtell's observation was to do with Kevin Bracken's racing engine, not road bikes). I've never heard it talked about by anyone else or in another context, so Brook's thoughts would be interesting.

P.s Never heard that thing about synthetics and gears. Hmmm. Nonetheless, I think I'll stick with fully synthetic as the factory recommended. Did you notice how he too has apparently failed to recognise the importance of "SINT" in 'Agip SINT 2000'?

Hi Craig,

Yes, the stuff about synthetics was interesting, and I wouldn't dare to question someone as knowledgeable as Brook, but I have seen a demonstration of how way, way, superior synthetics are in stopping seizures, which is demonstrated I suppose, in the way they do not allow piston rings to run in. Maybe it is to do with load-carrying abilities - I remember our tractor mechanic at work telling me that he would never use any lubricant in a gearbox without specific gearbox additives. Also, I do not see how a 20/50 multi can be superior to sae50 in a HOT climate - multigrades were designed to overcome high viscosity during cold starts, but this is not a problem in a hot climate as sae50 has a low viscosity when hot......

Colin

20/50 has the same viscosity as SAE50 when hot. But has significantly less when cold, which might improve coldstart lubrication and kickstarting.
If it were really important to run any gearbox with oil containing gearbox additives, all our Ducatis and millions of japanese bikes would be run illegally, or break down immediately when operated?
Interesting: since at least 25 years, multigrade oils for japanese high power bikes with their wet clutches are manufactured according to the JASO MA specifications. Reason: these oils contain additives which improve the friction coefficient of the clutch plates. And they lubricate gearboxes which transfer power of 200HP and more.
I run 20-50 multigrade for more than 2 decades in my 350, without any significance of problems.

cheers Hans

Like Hans I have run my 350 mk3 on 20/50 oil from new .....castrol, duchams, silkolene, whatever, with no issues at all, however about 10 years ago I experimented with semi synthetic for a while and the engine burnt a little oil? I then changed to Nigels recommended silkoline fully synthetic 20/50 for air cooled high performance engines and no oil burning? Regardless of this my bikes engine has never been stripped from new and is still on the original big end the only things that have worn out are the steel clutch plates which eventually became almost razor thin and cupped distorted, I have not been particularly kind to the engine other than regular maintenance and frankly have been reving the brains out of it for years . I probably shouldn't be saying this ......the bloody thing may well blow up the next time out
Cheers,
George

I'm with Hans on this one regarding SAE50!

However a good engine will run okay on it, but I don't think it's ideal.

Regarding Ducati Bevel twins being different from most other makes using roller bigends (which there are many!) and their unusual fragility:

1) The bevel twin has very heavy rods compared to most similar size engines/cylinders.
2) Invariably poorly balanced cranks
3) Invariably poorly manufactured and toleranced components
4) Invariably poor hardening
5) Poor filtration
6) Either 3mm rollers- no other manufacturer as far as I know uses anything smaller than 3.5mm, mostly 4 or 5mm rollers.
7) Or double row 5mm rollers- that tip and wear/tear in the middle. It line with Singles replacing double row rollers with longer single rollers improves things.

A few clues there

Having built Ducati Twin and Single cranks for 30+ years for road and race I've a fair imagination about why they fail and some of the reasons go beyond the cranks

I will add I've just finished two bevel twin cranks this morning (I know it's Sunday, but it's raining here), so I'm still at it and this is not just reminiscing from days gone by

Regarding High output (volume) pumps, they are not entirely necessary and "too much" oil in a roller bigend is certainly not desirable. However there are other major limitations in the original single pumps due to design and tolerancing, which I have touched on before in another post. The "High output pumps I sell are only about 25% extra and have many other benefits which are more important than the High output element. You must also remember the pump feeds the top end as well where a little more oil is a benefit for the cam and rockers and potentially for cooling. As I've said before I never fit the oil seals to the timing cover as they invariably fall out and as has been said roller bigends don't need loads of oil so a little loss here is not important. I would also add that in the past I have used the normal Italian 50% extra output pumps and not experienced any issues after many years of racing.....so even 50% obviously isn't a major issue, even if I don't think it's ideal.

Regarding clearance in the bigend assembly, yes Ducati twins and singles are a bit tight as original and I always given them a bit more clearance. "Strangely" much in line with bearing manufacturers specification and most other manufacturers! However I don't subscribe to some of the really large clearances recommended by other Bevel twin experts as another solution to the woes. I've never used more than 0.04mm in a twin and as yet not had any reports of issues. I think a lot depends on the stability of the rods. Most singles will run okay with anything from 0.015 to 0.035mm clearance. For me 0.025 to 0.030mm is the sweet spot for all applications. Leaving the slightly less clearance for the road bikes and slightly more for the race bikes.

I've always taken Ducati Folklore with a large pinch of salt and it's worked for me over the years. Repeating the same will only get you the same.

Regards Nigel

Thanks Nigel. AFAIK, it was Steve Wynne who convinced Taglioni to change to the 3mm rollers ( I don't know who advised him in this respect) and he was adamant that it was a big improvement. I always thought that it was strange that Smith Shoukai in Japan used 5mm rollers in their big-end assemblies and stated that they lasted longer. I'm wondering after what you said, that the improvement in twin cranks with the 3mm rollers was simply due to them spanning the whole width of the con-rod eye? I wonder if Ducati ever tried long 5mm rollers?

Colin

Colin

Apart from the double row rollers in the early assemblies and other ducati issues, i think for road use the dimensions are better for longevity. The Original straight plain alloy cages don't wear the rods like the 3mm steel cages, which soon reduces the effective length of the roller. I've seen and fitted one piece rollers to early assemblies and I'm sure it helps from what I've seen.

I think Laverda uses 5mm rollers as also does Yamaha for the latest versions of there big 660 singles like the MT03 etc. Yamaha went from 3.5mm to 4mm and then to 5mm with their big singles over the years. In road use maybe they are not doing the revs as a bevel twin being raced, but Yamaha singles have been raced very successfully using those larger rollers. Most Bevel twins never get ragged on the road and I would think they would last longer with a larger rollers suitably applied. I use a 37/45/22 Yamaha bearing in my 36mm pin twin kits with 4mm rollers which seems to work well. Phil Hickcock used Honda bearings with 4mm rollers as a repair for early bevel twins and as you say Smith Shoukai also used larger rollers (I thought 4mm, but it is a long time since I fitted one of those).

Unfortunately there is little choice other than the Ducati 38/44/22 bearing for the 38mm kits. There are no other 38mm I/D bearings and any 40mm bearings have large rollers leaving little available thrust face. The INA cage and odd length rollers used by Ducati are long obsolete, however Damien Birch in Australia does produce a plain (PTFE coated) alloy cage using 1mm longer rollers. So far so good with those, hopefully being superior to the other black wasted alloy cages available from Italy. I did have a few batches of Silver plated steel cages similar to the INA cages manufactured in the UK, but it became cost prohibitive years ago.

Enough of bevel twins, nice to ride, full of charisma and charm, but probably best appreciated in engineering ignorance, double the trouble, Singles rule

Regards Nigel

Enough of twins, nice to ride, full of charisma and charm, but probably best appreciated in engineering ignorance, double the trouble, Singles rule

Never tried a Ducati twin , my wife has a Honda Bros 400 v-twin that now has 100,000+ miles under its wheels, a 5 speed box that is like a knife through butter and tops the "ton". Bit top heavy and the tyres are too wide. Had a Morini K2, heavy, clunky gear change, with false neutrals, agricultural starter motor and like sitting atop a scaffolding board, handled OK, but hard work to maintain. Sound familiar?! Yamaha SRX 600 twin shock and a monoshock, the 5th gear pinion will loose teeth (poor hardening and too much torque) and spares are now getting scarce and expensive, if the later 660 engine doesn't use it. Lovely machines to ride though. Used 10/40w semi-synthetic motorcycle oil in them all and change it at the manufacturers recommended mileage along with the paper element filters, except the Morini that use Norah Batty stockings.

Proper oil filtration on Ducati engines, rather than a coarse weave pair of Norah Batty's stockings might help. I used to run a Royce Creasey, Renault 4 filter conversion made for me by Kirby Rowbotham, on the timing case of the 450 and it certainly made a difference in the appearance of the oil and inside of the motor, cleaner. But I was advised to remove it as it might affect oil flow to the top end, this was not by anybody on this forum. Maybe for debate on another thread? The benifits of having switched to a 15/50w multi-grade synthetic oil in the 450, in place of a monograde 40w mineral, mean that I shall be sticking with the multi-grade additives, rather than the old school goop.

Singles rule! Make sure you wear them out!

Good health, Bill

Velocette singles used 3/16" x 9/16" big end rollers on road bikes and racers since the mid-1930s at least.
That's close to 5 x 14mm - copied by many!