It was too good a deal to pass up.......

[luhbo]

Sorry for the affront then. It doesn't offense my enthusiasm, that would be too silly, I see such talk as an offense against my profession.

 

I have a buddy riding his Stelvio with the standard warranty replacement parts inside, built in after the standard warranty procedure from Guzzi,without any issues since another 100.000 km (comuting 100km per day from March mostly 'till December). That's correctly hardened flat tappets, correctly hardened cams, oil only flushed once to get the biggest debris out. Same design as before, works obviously fine now.

 

I believe that most often quality problems are mixed up with bad design work. Just take 'The Spring' as an example. Early builds work perfectly, next generation completely fails, last generation works again. Is that a design flaw then?

 

BTW, I consider roller tappets not being a clever solution. Never understood how they work on standard flat-tapped-cam profiles. Any suggestions?

[GuzziMoto]

Sorry for the affront then. It doesn't offense my enthusiasm, that would be too silly, I see such talk as an offense against my profession.

 

I have a buddy riding his Stelvio with the standard warranty replacement parts inside, built in after the standard warranty procedure from Guzzi,without any issues since another 100.000 km (comuting 100km per day from March mostly 'till December). That's correctly hardened flat tappets, correctly hardened cams, oil only flushed once to get the biggest debris out. Same design as before, works obviously fine now.

 

I believe that most often quality problems are mixed up with bad design work. Just take 'The Spring' as an example. Early builds work perfectly, next generation completely fails, last generation works again. Is that a design flaw then?

 

BTW, I consider roller tappets not being a clever solution. Never understood how they work on standard flat-tapped-cam profiles. Any suggestions?

I agree, roller tappets are not a clever solution. The roller tappets use a different cam. If they don't use a different cam the valve timing will be very different. Cams, as it sounds like you know, are either made for roller tappets or flat tappets. 

As to all flat tappet motors failing, I am only repeating what Pete Roper says. I thought the switch to roller tappets was a step backwards and I don't understand why they didn't just properly fix the flat tappet motor. But they don't listen to me.

[Lucky Phil]

 

Sorry for the affront then. It doesn't offense my enthusiasm, that would be too silly, I see such talk as an offense against my profession.

 

I have a buddy riding his Stelvio with the standard warranty replacement parts inside, built in after the standard warranty procedure from Guzzi,without any issues since another 100.000 km (comuting 100km per day from March mostly 'till December). That's correctly hardened flat tappets, correctly hardened cams, oil only flushed once to get the biggest debris out. Same design as before, works obviously fine now.

 

I believe that most often quality problems are mixed up with bad design work. Just take 'The Spring' as an example. Early builds work perfectly, next generation completely fails, last generation works again. Is that a design flaw then?

 

BTW, I consider roller tappets not being a clever solution. Never understood how they work on standard flat-tapped-cam profiles. Any suggestions?

I agree, roller tappets are not a clever solution. The roller tappets use a different cam. If they don't use a different cam the valve timing will be very different. Cams, as it sounds like you know, are either made for roller tappets or flat tappets. 

As to all flat tappet motors failing, I am only repeating what Pete Roper says. I thought the switch to roller tappets was a step backwards and I don't understand why they didn't just properly fix the flat tappet motor. But they don't listen to me.

 

Not a lot wrong with roller lifters really. Chevrolet have been using them for years on their later generation of V8 engines. Little friction, totally reliable,ability to use more aggressive cam profiles, no real need for cam/tappet breakin,turn hi revs reliably, smaller package size overall. Downside...a little more weight and complexity.  

Over the years working on what you might call hi performance engines its valve train wear/failure on the highly loaded sliding/rubbing surfaces that is the common high wear/failure point. 

Not saying its necessarily a weakness in all cases but its where you go looking first. Roller lifters arent elegant but they do work. I like them.

As it happens I just fitted the V11 with a new set of rocker arms yesterday while doing the Grisso valve cover conversion. At 42,000klms the old rocker arms had the typical wear on the valve stem foot that makes clearance setting harder than it should be. They would have gone more miles but I had a new set so threw them in. If the engine had a set of roller rockers wear at this point wouldnt have been an issue. Might look at getting this conversion done on the old rocker arms. 

 

Ciao

[LowRyter]

my 94 Camaro had rollers.  So does my 08 'vette.

 

(my car has roller tappets, not rockers)

[Lucky Phil]

my 94 Camaro had rollers.  So does my 08 'vette.

Yea they have been around for years but in the early days serious engine builders used to go for the flat solid lifters. Now its the other way around and rollers are used in high performance engines.

Some US car race series still mandate the use of flat tappet cams and its a limiting factor to higher outputs.

 

Ciao

[pete roper]

Sorry for the affront then. It doesn't offense my enthusiasm, that would be too silly, I see such talk as an offense against my profession.I have a buddy riding his Stelvio with the standard warranty replacement parts inside, built in after the standard warranty procedure from Guzzi,without any issues since another 100.000 km (comuting 100km per day from March mostly 'till December). That's correctly hardened flat tappets, correctly hardened cams, oil only flushed once to get the biggest debris out. Same design as before, works obviously fine now.I believe that most often quality problems are mixed up with bad design work. Just take 'The Spring' as an example. Early builds work perfectly, next generation completely fails, last generation works again. Is that a design flaw then?BTW, I consider roller tappets not being a clever solution. Never understood how they work on standard flat-tapped-cam profiles. Any suggestions?

All the flat tappets fail, it's not a material issue per-se, well it is but why it fails is not down to the reasons most people think they fail.

 

Tell yer Stelvio owning mate to drop a cam box off and check the DLC. It will be failing. Then look at the cams and see the signs of damage on them. If you're half as much of an engineer as you are a smug bastard it will be obvious to you why the system shits the bed.

 

Pete

[docc]

I had to look this up. New term for me. Always learning here . . .

 

"DLC Coating stands for diamond-like carbon coating, and is a nanocomposite coating that has unique properties of natural diamond low friction, high hardness, and high corrosion resistance."

 

 

(To my novice mind, this sounds like a very hard, but thin, brittle layer.)

[Chuck]

I had to look this up. New term for me. Always learning here . . .

 

"DLC Coating stands for diamond-like carbon coating, and is a nanocomposite coating that has unique properties of natural diamond low friction, high hardness, and high corrosion resistance."

 

 

(To my novice mind, this sounds like a very hard, but thin, brittle layer.)

I know enough to know what I don't know about DLC, Docc.   Yes it is hard. I *think* it is deposited by plasma spray. 

[GuzziMoto]

I have front forks with a DLC coating, and at some point I need to get DLC buckets for my Aprilia XV motor. They also use DLC on shock shafts, but I don't have that as far as I know. It is cool stuff, but it seems to be debatable as to whether it is suited to lifters. As I mentioned, it is the hot ticket for XV buckets. The non-DLC buckets fail.

[pete roper]

The original tappets used on the 2008/9 8V's were chilled cast iron. These were of dubious quality due to heat treatment issues and a lot failed, (Mine didn't. I was an 'Early Adopter' of the 8V) because of this. The first factory 'Fix' was a swap to forged steel tappets with a DLC coating on it. All very clever but it missed the target due to other components in the valvetrain and the fact that the 8V's run so very cool.

 

After a few months it became apparent that the fix didn't work as the failures continued, not generally as rapidly but they still occurred. By the middle of 2010 the factory knew, categorically, that the flat tappets weren't going to work. They also realised the solution was to go to rollers, or if my belief is right, return to rollers which I believe the engine was originally designed for before some bean-counting wonk over-ruled the engineers.

 

How did I deduce this? Simple really. From that point in mid 2010 there was another *Update* to the flat tappets, they gained a B0 part number with the suffix 'Final' but not only that but during assembly of the motors the cylinder heads started to be marked with a drill mark in the paint which indicated that some of the important componentry of the change to roller tappets had already been installed! Why would they do such a thing unless they KNEW they were all doomed and wanted to save themselves money as inserting those parts requires removing the heads. This probably needs a bit of further explanation.

 

There are four 'Kits' available for conversion of flat tappet engines to rollers. Early, pre mid 2010 models without the drill Mark in the paint require the more expensive 'C' kit. This requires the heads to be removed to insert shims under the inlet valve Spring seats, presumably to increase the seating poundage of the valves to avoid float due to the slightly more massive nature of the roller tappets.

 

Models from mid 2010 through to late 2011 require the 'B' kit. This does not require removal of the heads as the shims are already in there.

 

From late 2011 through to the change over point in early-mid 2012 there is a third kit, the 'A' kit required but this is because of changes to the spark plug tube arrangement and rocker cover sealing, nothing to do with the valves.

 

The final kit, the 'D' kit, is specifically finally for later model 1200 Sports which had the later rocker covers etc. but none were ever manufactured with the shims under the valves so, like 'C' kit bikes, the heads have to come off.

 

Getting back to business though one has to ask why, since they knew that all the flat tappet engines were going to fail and knew that the fix was rollerisation, they didn't just start building them with rollers? Well my belief is that at that time there were no rollers available but when they did have a sub-contractor up and running they were gearing up for production and launch of the Cali 1400. With the reputation of the 1200 motor already in the toilet a decision was made to stick all available roller top ends into the Calis and in an act of incredibly cynical bastardry just continue selling 1200's KNOWING they were going to fail.

 

When sufficient roller top ends were available they started puting them in the 1200's, (Presumably after the rush of new model purchasers had slowed and Cali production could be eased off.) and finally, rather than issuing a recall with a 'Mea Culpa' they issued a 'Technical Update' where, if certain extremely stringent conditions were met, when the flat tappets failed, Piaggio would supply a kit for nothing but you'd still have to pay for installation! If you couldn't meet those conditions you got hung out to dry. It was unconscionable!

 

As it is I've done a lot of rollerisations now. I stopped counting at about a hundred. I defended the flat tappet design for years because I wasn't seeing evidence of failure, (You don't until it is very far advanced.) but they were failing. As soon as I started seeing failures though I instituted a strict policy. Any flat tappet bike that came into my shop, whether it was displaying any symptoms or not, I pulled a cambox on to check the tappets. If the customer said 'No' my tools stayed in the box. Why, because it became immediately apparent that the failure rate is 100%! Some may take a bit longer than others but they will all fail. By 20,000km there is always visible damage to a tappet. By 30,000 they will all be 'Bullseyed'. I have also seen tappets hollowed and concave at under 11,000km!

 

I'm pretty sure I know the reason for the failure too. It's a combination of factors, not just one, that kills them. Make no mistake though. They will all die.

[68C]

To ease my paranoia, please confirm this flat/roller tappet debacle only concerns the 8 valve motors.

[pete roper]

Yes, only 8V's manufactured between 2007 and the middle of 2012.

[Chuck]

Thanks, Pete.. 

[LowRyter]

wow.

 

Why not just go with a 1400 kit then?

 

[pete roper]

Single sparking a 1400 is a much bigger job than simply swapping the barrels and pistons over Jon. As you know, we've bin there and done that.

 

Behold, a Griso 1400 in the wild!