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I haven't had heads on the bench for comparison but the later pistons have a different crown design. They may also be completely different weights which produces a whole host of different problems.I'd also guess it would be very pricey. I just bought a pair of piston assemblies for a 1400 Cali for another project I'm working on and didn't get any change out of $800AU.A sump extension and checking your oil frequently is a far cheaper option.Pete
I think part of the problem is that though we've heard/seen a few occurrences over the years no one knows for sure what happened/why and therefore how to be sure to prevent it.I seem to recall Pete mentioning a customer who lent his fine running, seemingly non-oil burning bike to his daughter who took it on a higway run and burnt up the motor in a couple hundred kms.Ironically this is why I ordered and installed a sump extender on my first year 1TB V7 only to later discover I probably didn't need it. But then again it makes me feel warm and fuzzy to this day.If I had an older model I don't see it worth it to chase the issue another way.
On the engines I've seen, (4 or 5.) that have done this the rings and groves were all well within tolerance. It's very weird, the air boxes are usually dry and the engines don't smoke. Even the plugs look OK.As I said I'm baffled by what might cause it but it happened!
I agree with your thinking. The sump extension is more peace of mind, simply because it increases the margin of time you have available from the start of problem to huge, expensive damage.I am completely ignorant of this event in the Moto Guzzi world. All I know is what is in this thread. From Pete's original description, rapid change from no problem to burning lots of oil, it sounds like one or more stuck rings. If it ever happened to me, I'd switch from educated engineer, back to my redneck, farmer roots and treat it like a old farm tractor. Perform a compression test and/or a leak down test. Remove both spark plugs, rotate the engine until the pistons are mid stroke, and fill the cylinders with motor oil or kerosene and check often to see if one is draining quicker than the other. Then perhaps fill both cylinders with penetrating oil, and refill often for about a week. Drain the crankcase, refill with motor oil and start it up and check oil consumption.If that didn't help, it might be revealing to pull the pistons and check for stuck or broken rings, measure ring end gap, and piston cylinder clearance.It would also be interesting to know if this primarily happens in bikes that are not ridden or started often. Or only to owners who use cheap gasoline or cheap oil. A rare problem? But with expensive consequences. And little diagnostics performed when it occurred.
Please define cheap oil and gasoline.
I suspect it may also relate to how they were run in; I spent considerable time going up and down our Port Hills two up loading the rings up but not lugging the donk.
E 85 basically isn't gasoline. And it doesn't matter where the oil is purchased.If the oil meets spec its good oil.And I don't know of any motorcycle that can run on E85.How about E100? Is that cheap stuff?
I've recently acquired a 2011 V7C that suffered this vanishing oil syndrome. 127,000km on the clock, the owner said the oil would vanish in a few hundred kms, no smoke, no leaks, no oily plugs, just gone. The final straw - the dipstick blew out with a truck on his tail. By the time he could pull over, it was too late. I bought the gearbox, and he threw in the rest of the bike. Other than some of bits he pilfered for his Stone, it's pretty well complete. And as I have a low km Breva motor sitting on the shelf ......My 2010 V7C has always used some oil between changes, in spite of a careful running in (oil change at 35km - lots of metal swarf - running in oil for 500km, another oil change then, 1000km of mostly tight & hilly twisties & the dealer first service at 1000km, 6 days after I bought it). Still going strong at 210,000km, although there are no some rattles that I'm keeping an eye and ear on. The 2014 Special, on the other hand, doesn't appear to use much oil at all between changes (at each 10,000km).
very interesting, thanks for sharing. Are the 2010 and 2011 both the twin TB models? Was 2012 the year of the switch from twin to single TB's?Dip stick blowing out seems like a crankcase venting issue. Maybe related?.........
The thing is it's not a constant consumption problem overlooked by owners. It's a sudden, inexplicable, loss of large volumes, (As in all of it!) of oil. Bikes that won't use a drop for tens of thousands of km will suddenly do it! It's not easy to point at a 'Smoking Gun' when there isn't one.The one thing that can be said is that whatever the cause it seems to have been fixed with the piston and ring changes on the later models.That's all I can tell you and I've stripped two motors that have done this trick and could find no reason. That doesn't mean I didn't miss something but I'm no dummy and was looking for any hint of an explanation.Pete
As for identifying the different motors here are some visual aids.Jay's first Guzzi (2TB V7C, maybe 2010 or 2011 IIRC) parked to the right of my first smallblock 1TB 2013 V7 Stone (first one delivered to FBF that wasn't the "demo" bike):And here is our 2013 MKI V7 Stone again next to our 2018 V7III (Hemi head):As you can see the visual cues at the jugs/heads are striking enough to catch your eye once you know for what to look.
Kev, any significant performance differences between a twin TB 750 and a single TB 750? If you close your eyes while riding, can you tell which bike you are on?
Well technically I'm from Manhattan, but I lived most my life in PA till my darling wife, fresh off 28 years of school decided to get a job and upended us. We landed in South Jersey, just miles from a 100,000 acres of pines. Not what most people think of when they think NJ.But I'm starting to think maybe that's cause the locals want it that way.
