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I don't understand why I am getting "we have discussed this before" in response to my specific questions about these specific incidents that you have been experiencing of late, Pete, but I have been following this issue with great interest, and I believe these are important questions that have not been previously answered. (How could they? They pertain to incidents that you first disclosed in this thread one day ago.) Of course, it is your prerogative to ignore them, but I really wish you wouldn't.
Am I courting disaster by running my 09 griso 8v in cold weather?
Is it advisable to let it warm up at idle?
Should I periodically pull the cam boxes to inspect for wear or is close monitoring of valve lash adjustment adequate to catch this early?
Love this bike, but wont have a bike I cant ride because its cold or damp. Enough questions for now , thanks Dave. ps I realize there is probably no simple answer to these questions.
The above photo of the tappets with the DLC missing in the centers interests me. Since DLC is a non-wearing very thin coating I'd think the tappets would be ground absolutely flat and would run on a cam lobe that was also flat (rather than the conventional very slight crowned tappet and tapered cam lobe). No matching "break-in" wear would occur with DLC coatings. SO...my question is: Are the DLC coated tappets and matching cams ground flat or has Guzzi coated tapered parts and caused localized overloading of the tappet resulting in lost DLC in the centers? Once that coating chips it'll be like a lathe cutting the cam lobe down. Might be I'm all wet here but that's what crept into my feeble mind this afternoon as I attempt to thaw from this hellish cold spell! Terry
I was absolutely anal about stuff like valve clearances during break in and yes, they do close up appreciably Pete
Initially the seats will settle in the heads, there is also stuff like assembly lube that will was out allowing clearances to change, freshly cut seats bed as the valves settle into the margins. Almost all valves will close their gaps in the first few hundred Km/hours of use, some more than others. I would of thought you'd of known that?Pete
This, AFAIK there is only one place to lose valve clearance, find it and you have problem solved. If not the valve recessing, where is the clearance going ?
Sorry, but the reason I say it's been discussed before is because it has, almost endlessly, in a multitude of threads. Those who are interested will either of seen these ramblings or, if they wish, can do a search here or on any one of a number of boards and get the skinny on how and why I developed my theory as to why the damage occurs and why geographical location is relevant.It is neither necessary or useful for me to completely re-state every step I have undertaken to analyse and rule out different causes for the failures....
The reason for the slight dome on the lifter face along with the lifter bore being slightly off centre with the cam lobe centre line and a slight taper on the cam lobe is to cause the lifter to rotate and present a fresh surface to the cam and promote oil renewal between the surfaces.There are 2 ways a lifter fails, one is due to oil film loss and the subsequent micro welding pulling the hardening off the face and the other is fatigue.All of that loading and unloading of the coated or hardened face eventually causes fatigue below the surface and the surface breaks away. Hence the need to still have the lifters rotate to distribute the fatigue evenly.The same applies to roller bearings, even properly lubricated and protected a roller bearing still has a "life" due to fatigue issues.Ciao
One of my early thoughts was non-rotation of the tappets but if that was the case I would of expected different wear patterns. With your far greater experience of failures of this type I'd be interested in your opinions. I'll drag out a selection of tappets tomorrow and take some pics.Non rotation wouldn't explain the geographic and climatic pattern to the failures though.Pete
If there is some other reason why you don't want to answer, well... again, your prerogative to tell me to "bugger off."
This is true, and I understand it. However, I work daily with a number of diesel engines from a variety of manufacturers and those using tappets with hard coatings or inserts (like the 500 series JD diesel with Carbide disc inserts in the tappets) have no crown and no taper. Only the offset from center to promote rotation. My thoughts are based on these facts as the physics involved seem to fit the pattern of failures seen in some 8V Guzzis. Terry
No, why should I tell you to bugger off? I'm not going to spoon feed you either. All of those questions have been covered extensively over the last few years....
So, to be clear, FOR THE 8V FAILURES THAT YOU FIRST REPORTED HERE THREE DAYS AGO (and ONLY in regard to those bikes):How many of these have you seen?Can any of the failures be attributed to poor break-in, lack of proper maintenance, or abuse? Or is it happening despite the owner doing everything "by the book?"Is there any pattern as far as model, year, or date of manufacture?Are these engines still under warranty? For bikes either within or outside of the warranty period, what has been the factory's response as far as parts, repairs, and financial responsibility?What does fixing this entail, and what is the cost? Are the failed engines getting upgraded to roller tappets?Have any of the failures occurred among the engines with roller tappets? If not, from the damage that you have inspected, do you anticipate that the roller engines will not have these failures?FWIW, I am not asking out of idle curiosity, but to inform future purchasing decisions.
How many of these have you seen?Can any of the failures be attributed to poor break-in, lack of proper maintenance, or abuse? Or is it happening despite the owner doing everything "by the book?"Is there any pattern as far as model, year, or date of manufacture?Are these engines still under warranty? For bikes either within or outside of the warranty period, what has been the factory's response as far as parts, repairs, and financial responsibility?What does fixing this entail, and what is the cost? Are the failed engines getting upgraded to roller tappets?Have any of the failures occurred among the engines with roller tappets? If not, from the damage that you have inspected, do you anticipate that the roller engines will not have these failures?FWIW, I am not asking out of idle curiosity, but to inform future purchasing decisions.