Oil Filter

[Duccout]

Just an addition to Nigel's experiences: both Brook Henry and Don Godden have both increased the radial clearance on the big-ends that they produce for Ducati vee twins, which adds weight to the theory that the clearance is a bit tight from Ducati, and it is worth noting that the early 750 Super Sports used to throw rods, due to the aluminium cage seizing in the con-rod.

There is much difference of opinion about the bearings too: Steve Wynne said that failure rate of the 38mm big-ends was half the rate of the 36mm; Kevin Cameron has described how German aircraft engineers in WWII discovered that smaller diameter rollers increased the life of big-end bearings, due to the lower mass; but Smith Shoukai in Japan produce Ducati big-ends with 5mm rollers and claim that they give longer life than the 3mm rollers.

I think that it depends on how well the engine is assembled and if the engine is thrashed or not.

[marsheng]

Some interesting reading on big end rollers from INA FAG. Crank end guidance and piston end guidance

https://handel.pro/content/catalog/2ac63b76-f129-499c-81f8-2ff57d3f3ee8/EN/FAG_Needle%20roller_tpi94_de_en.pdf

Cheers Wallace.

[LaceyDucati]

Wallace

That's a good guide, I have a copy from the nineties that I used as a base line for my specifications. The guide specifies that the recommendations are for "general" conrod assemblies (compressors etc). That said it has some pretty tight tolerances and is in line with what I use. I will add at this point that some "Race" rods are wildly outside these tolerances and extremely unstable in use. This is probably more the reason many use larger clearances to try and compensate in some way. Most OEM Yamaha/Honda etc rods are far superior in accuracy. I used to use INA bearings which worked well, but I prefer to use Japanese bearings now due to cage design and numbers of rollers.

Regards Nigel

[marsheng]

I do a few crank rebuilds. Just did a Yamaha YZ450F and decided to remove the plug from the end of the pin to see how much debris was in there. Not much. Ok, it is a dirt bike from around 2003 so it may not have not had too much use.

I then looked at an Suzuki FXR150. This would be in the 20-40K range. Bear in mind that these don't have dedicated sludge traps but the big end pin would act in the same way. The debris would therefore be the full amount and not limited to what the sludge trap would have skimmed off.

Here is the photo. Only on one side and not even the full length of the pin.

PinBuildup.JPG

My bigend pin on the 250 was quite full.

Anyone want to buy a retrofit oil kit ?

Cheers Wallace

[Duccout]

You have a point, and no-one would argue that an oil filter is not a Good Thing, it is just whether the trouble of plumbing one in outweighs the trouble of dirty oil running round in the engine.

Condor obviously felt that a filter was necessary.

[Jordan]

Condor obviously felt that a filter was necessary.

I think it's likely that the makers of Condor were complying with army requirements.
Military vehicles may be called upon to perform under harsh conditions for extended periods of time.
That is in contrast to the careful, limited use and timely maintenance our personal bikes surely average.

[blethermaskite]

Many years ago I was a great fan of Fiat's 850 sport coupe, and owned several of them,most had terminal rust problems but also had really quite high mileages in and around the 80/90k mark, out of 4/5 engines I stripped for spares each one had a perfect std crankshaft with little or no wear on the journals or the shells.....these engines have a centrifugal oil filter fitted to the end of the crankshaft not unlike a 60s Honda twin, for me again proving how effective the centrifugal oil filter/sludge trap is in practice, add a magnetic sump bung and keep up a regime of relatively low mileage good quality oil changes and I think further complication is unneeded...... Other opinions are of course available
Cheers,
George

[marsheng]

Tthese engines have a centrifugal oil filter fitted to the end of the crankshaft not unlike a 60s Honda twin, for me again proving how effective the centrifugal oil filter/sludge trap is in practice, add a magnetic sump bung and keep up a regime of relatively low mileage good quality oil changes and I think further complication is unneeded...
Cheers,
George

I'm very happy with a centrifugal filter, its just where Ducati put it that it is a problem. Really only serviceable by a Ducati expert.

Just to give an idea on the difference between the Suzuki and Ducati here is a new photo.

Debris.JPG

If this bike had done 20k then, it is good for at least 100k and by that time it would need a new rod. On the other hand, my 250 had probably a tablespoon of buildup and was close to being fully blocked. I doubt it had done more than 30k.

Ok so what about the frequent oil change. This thread got me pondering on this. Say the oil pumps 1 cc per rotation. At 3000 rpm, that is 3 litres a minute. So, roughly every minute, the oil is pumped through the motor and the centrifugal filter. In a 10 minute ride, the oil has then circulated 10 times. If the oil is now changed, it really only has the debris from the last time it has been pumped through the motor which would be approximately 1/10 of the debris produced in the 10 minutes. So is it worth doing ?

Oil does break down so frequent changes insures all the additives etc are in prime condition, but I'm not sure that it has much to do with keeping the engine debris free ?

Happy to be corrected.

Cheers Wallace

[Jordan]

my 250 had probably a tablespoon of buildup and was close to being fully blocked.

If the sludge trap is full of debris, does this mean it blocks the oil feed to the big end?
Has anyone found a Ducati crankshaft that would not pass oil?
A test could be a syringe of oil applied to the end of a crankshaft.

I'm thinking that it might be that once the trap is full, unfiltered oil could continue flowing, because it's being pushed under pressure.
It would be as if the centrifugal filter was no longer there.

I also would be deliriously happy to be shown otherwise.

[Duccout]

That would be my understanding also; surely, once the trap is full, it would just be a normal oilway?