Oil Filter

[LaceyDucati]

George

I like your realistic explanation! Reminds me of a guy I know with a 250 Desmo who did 70 000 miles on the original engine. As evidence he showed me several Smiths speedos, many without attached needles! I suppose those restoring bikes to factory spec, can relive every aspect of the original Ducati experience

Regards Nigel

[marsheng]

fyi: http://motoscrubs.com/Ducati_Tech/oilfilter.pdf

..

That is where I got the idea. Cheers

[marsheng]

From the replies, there have been been many bikes with high mileage with the standard setup so it does work. I guess I am biased, as my 900 SSD died at 35000 from big end failure.

On stripping that and the 250, both had substantial buildup in the sludge traps. The 900 was full and the 250 probably around 80%.

I think the hole in the crank is a bad idea. Have to strip the motor and crank to clean it out. Honda had a better idea with the centrifugal filter on the end of the crank. Easy to access and clean out.

https://thumbs.ebaystatic.com/d/l225/m/mAxQ0P67Atv1rmw2B_ZnDgA.jpg

Now that I have plumed into the oil, I can add an oil pressure switch which would be handy. On that line, the Honda's oil pressure went over 60PSI when cold and then settled to around 8 when warmed up. PS my race Honda CB150 died when the oil got low. Crank seized.

Here is a very old clip. I do hope I sound more Kiwi now than South African.
https://www.youtube.com/watch?v=PsEFKYULNDc

PS this forum would not exist if we didn't tinker with bikes !!! Besides, that is what workshops are for.

[Jordan]

I think the hole in the crank is a bad idea. Have to strip the motor and crank to clean it out. Honda had a better idea with the centrifugal filter on the end of the crank. Easy to access and clean out.

https://thumbs.ebaystatic.com/d/l225/m/mAxQ0P67Atv1rmw2B_ZnDgA.jpg

I've seen it on Russian bikes too, maybe copied from pre-WW2 BMWs?
It's a nice way to do it, but kills a nice little earner for the spare parts department, selling disposable filters.

Russian-oil-fliter2.png

Sludge traps were commonly used on British parallel twins. Nobody seemed to have a problem with them.
I could stand corrected, but if the crank filter on Ducatis becomes full up with debris, does it not just let the oil pass, without any filtering effect?
That is, no clogging of the passage and oil starvation?

My theory about Ducati twins of over 750cc is that the roller big ends are not capable of the engines' high torque output. So, at low revs they get a hammering to destruction, not common on 750s that need to be revved more.

[marsheng]

I could stand corrected, but if the crank filter on Ducatis becomes full up with debris, does it not just let the oil pass, without any filtering effect?
That is, no clogging of the passage and oil starvation?

If it gets clogged, there is a serious problem somewhere else. If it did, then by that time, the sludge trap would probably also be fairly full as well. This filter does have an internal bypass valve just in case there is a serious problem.

One advantage is that in doing an oil and filter change, it is easy to spot foreign debris in the filter. Hopefully avert a more serious future disaster.

A local friend added a similar paper filter to his Guzzie that had the usual centrifugal filter. Last seen at 70000 km and still going strong. Apparently non of the others are still running.

Bypass valve. If I have the correct original spring in the oil pump, it takes 1.2 kg to open it. The hole is 4 mm and according to my calcs, that is 135 psi. That is a lot.

[graeme]

Hello Wallace,

I do commend you for trying to improve things on an old design that was built to a dollar 50 odd years ago.
They are tough little engines as long as the oil is changed regularly and they are ridden remembering that they are an old design.
I’ve never had a single engine fail from lack of oil. Or a blocked sludge trap.
I change oil at least every 1000 ks. Use good quality oil and don’t “slug” an engine at low revs and lots of throttle.
I have had them shit themselves for other reasons, mostly me trying to get more from them than was intended.
I think it’s more important to get good oil flow to the cam and rockers that to the big end.
From my experience. (Personal experience only)

Regards
Graeme

[Duccout]

I don't know about the filtration issue, but I asked a Silkolene oil technician whether I should be using no-detergent or detergent oil in my bevel 750 and he told me that medium detergent oil was correct even though the 750 has only the gauze filter; he asserted that there was very little difference between the Ducati gauze and a paper filter, and the gauze was very efficient!

As for big-end bearings, I go back to Harry Westlake's statement that revs is the killer, due to loadings on the rollers flexing the hardening. The reason that 900 Ducatis wear big-ends faster is because they have heavier pistons (which Taglioni tried to counteract by reducing the small end size) and shorter con-rods which run at a greater angle, plus Ducati got the radial clearance wrong,which needed to be greater. I don't think that running at low revs hurts big ends; AFAIK, Harleys and Panthers do not have a reputation for destroying big-ends and they run at very low revs.

I talked to two racers with 900 bevels at Brands Hatch a while back - one told me he gets one season out of a big-end, but the other told me that he gets two seasons; when I asked him why the discrepancy? He told me: "Ask him what revs he takes it to."

[Jordan]

My theory could be wrong but I'm not convinced otherwise yet.
450s have the same bore & stroke as 860/900s, but they are light bikes and generally get some revving to move them along.
No fair to compare big end performance and longevity with other makers'. They might have many differences, including engine power output.
For example my own Panther single uses a crowded roller big end for improved low speed longevity, and has very modest power for its 600cc.

[Duccout]

I forgot to mention that CR Axtell, the famous Harley tuner, discovered the reason for Ducati big-end failure in the bevel twins was due to the oil not returning to the sump quickly enough at high revs - the oil becoming trapped in the heads and above the sump, allowing the big-ends to run dry and overheat. This would probably apply to a bevel twin that was used for high speed motorway cruising, and I'm assuming that this is why the Singles have direct drains from the cambox when racing?

[ducwiz]

George, thank you very much for this elaborate cuuriculum vitae of your 350! So, >40000mls with the same big end is really impressing.
Might be twice of my mileage, which is ~38000km, presently. My 350 is a '73 Desmo with a Grimeca DSLS front brake, put together from bits and pieces in boxes I purchased around 1982. One of the previous owners fitted a Ceriani GP fork instead of the Marzocchi, which was probably destroyed in an accident. The engine is also of the late type, with 32mm bigend dia., but seems to be italian, as it came with a Ducati CDI, not Motoplat. Among other parts, I purchased a new crankshaft, also from Italy, and changed the oil every ~1500-2000km. I confess: up to now, I did not open the sludge trap ...
It has now the second piston, and the second set of valve guides. I got the seats on both valves reground, so reused them. Every 6-8000km I check/adjust the valve clearances. I remember that I got the rockers re-chromed once, at an unknown mileage.
As speedo and tach (and some other parts) were missing, I bought a white Veglia competizione (it was below 100 DM in 1982). And the german VDO company made me a special speedo of 60mm diameter. This one never failed to this day, but I heard from other german Ductisti that neither CEV, Veglia nor Smiths instruments usually lasted longer than a year.
The 6 Volt headlamp bulb broke roughly every 500km, i. e. failure due to the vibrations, not overvoltage. I always had on or two in a pocket of my Belstaff jacket (later a Barbour), when I was on the road at night. After converting the electrics to 12 Volt, the bulb lasted much longer.

Cheers, Hans