Bjor Posted February 9, 2012 Share Posted February 9, 2012 I'm installing my new Mike Rich pistons, and give the cylinder heads an overhaul while being at it. I noticed that the tappet of the right hand exhaust valve is slightly pitted, and consequently will be replaced. As I understand, it is quite normal that just this tappet gets it, due to a not perfect oiling system in our Italian beauties. However I don't think it has gone as far as to damage the camshaft... But the rocker of the the right hand intake valve does not look nice. Is this part hardened, so that once wear has gone through the hardened part it will accelerate? What's the reason for this wear? The bike has less than 50' km, and all the other rockers are fine... Anything to do with it, or should it be replaced with a new one? Link to comment Share on other sites More sharing options...
Gio Posted February 11, 2012 Share Posted February 11, 2012 I will leave for more experienced members to answer your question, but there have been a few cases of wear reported recently which has prompted me to include a look at the valvetrain on my '00 as part of the adjust/head torque work this weekend. Lex Stockton did a very good write-up on this procedure in the FAQ section - but perhaps adding an inspection of these items would be a good idea whilst the rocker arms are removed ... Gio Link to comment Share on other sites More sharing options...
luhbo Posted February 11, 2012 Share Posted February 11, 2012 Mine would make another 50.000 with these, probably. You can regrind and polish the rockerarm using an oil stone. Pitting is not a matter of oiling and not uncommon at highly stressed parts (gears, reardrive e.a.). Hubert Link to comment Share on other sites More sharing options...
Bjor Posted February 11, 2012 Author Share Posted February 11, 2012 I will leave for more experienced members to answer your question, but there have been a few cases of wear reported recently which has prompted me to include a look at the valvetrain on my '00 as part of the adjust/head torque work this weekend. Lex Stockton did a very good write-up on this procedure in the FAQ section - but perhaps adding an inspection of these items would be a good idea whilst the rocker arms are removed ... Gio Thanks Hubert! The tappet still has the right curve, and will most probably function for a while. The question is whether the pitting will accelerate or not once it has started. And I don't know when I will dismantle the cylinder again... But why grind the rocker arm? Is it to prevent it from damaging the stem of the valve, or is it to get a more even surface and thus a more accurate valve clearance? How much should I eventually grind off, just the edges, or should I grind back the original curve (which would be quite a lot...!) Link to comment Share on other sites More sharing options...
thumper Posted February 11, 2012 Share Posted February 11, 2012 That rocker looks a lot like a Ducati 996 rocker that did and does have flaking problems. They are crome plated on the wear pads. EMS will grind and replate a Ducati rocker they may do a Guzzi as well. Loose valve clearances is one of the main causes for the Ducati wear, I am wondering if all of us going to the looser world spec. on the valve adjustments this is the reason we are seeing a lot more tapet, rocker and came wear. Just a observation. What valve clearances were you running? Link to comment Share on other sites More sharing options...
Gio Posted February 11, 2012 Share Posted February 11, 2012 Not wishing to hijack Bjor's thread, but I have made similar observations. The left side rocker arm pads were very smooth, but right side have some very small pits (detectable via fingernail) - particularly the exhaust (see attached pic - may not be obvious). Bike has just under 85,000 km and I was running 6 and 8 thou clearances (measured 7/9 before re-torque) but think I will back these down to 5/7 or even 4/6 again. So I guess I have the same question as Bjor - to try and grind / polish out the pits or will this do more damage than good ..? Link to comment Share on other sites More sharing options...
thumper Posted February 11, 2012 Share Posted February 11, 2012 If a Ducati rocker looked like that they would be recromed or replaced. Metal to untreated metal will wear quickly. I know the valve setup is very different between the bikes But it does seem odd that now the goose has somthing in common with the duck, FLAKING ROCKERS. I have a 2000 996 and had to have 4 rockers recromed.If others have just cleaned them up and reused please chime in and let us know how long they have gone and do the valves need more frequent adjustments. Link to comment Share on other sites More sharing options...
luhbo Posted February 12, 2012 Share Posted February 12, 2012 ...But why grind the rocker arm? Is it to prevent it from damaging the stem of the valve, or is it to get a more even surface and thus a more accurate valve clearance? ... I noticed that over the time the valve train became remarkably louder and I thought this particular point could be part of the emissions. It was not. Anyway a smooth surface there could take off some stress from the valves' endings, as you wrote already, otherwise the valve guides will go even quicker (bigger lateral forces). If you still have the heads off you could consider the Guzziology idea of arming (and enlarging) the valve ends by putting Ducati shims over them. Hubert Link to comment Share on other sites More sharing options...
Bjor Posted February 12, 2012 Author Share Posted February 12, 2012 If you still have the heads off you could consider the Guzziology idea of arming (and enlarging) the valve ends by putting Ducati shims over them. Hubert Good idea! I will order. Do you buy your stuff from Stein Dinse, since you are located in Germany, or do you have any better suggestions...? Link to comment Share on other sites More sharing options...
Gio Posted February 12, 2012 Share Posted February 12, 2012 ...But why grind the rocker arm? Is it to prevent it from damaging the stem of the valve, or is it to get a more even surface and thus a more accurate valve clearance? ... I noticed that over the time the valve train became remarkably louder and I thought this particular point could be part of the emissions. It was not. Anyway a smooth surface there could take off some stress from the valves' endings, as you wrote already, otherwise the valve guides will go even quicker (bigger lateral forces). If you still have the heads off you could consider the Guzziology idea of arming (and enlarging) the valve ends by putting Ducati shims over them. Hubert Not planning on removing the heads in my case, and so I guess my choices are 1) grind/polish to remove the pits (not sure how much material can safely be removed - Hubert?) 2) replace the rocker assy ($$$) or 3) re-install and keep an eye on clearance for any further wear ... very tempted to go this way! Based on the pics, it looks like Bjor's rockers have experienced greater wear than mine (and in significantly less km's) and so I would ask the same question as thumper re what clearances were used..? Of course this could just be a production/batch issue and not related to clearance. Link to comment Share on other sites More sharing options...
Bjor Posted February 12, 2012 Author Share Posted February 12, 2012 ...But why grind the rocker arm? Is it to prevent it from damaging the stem of the valve, or is it to get a more even surface and thus a more accurate valve clearance? ... I noticed that over the time the valve train became remarkably louder and I thought this particular point could be part of the emissions. It was not. Anyway a smooth surface there could take off some stress from the valves' endings, as you wrote already, otherwise the valve guides will go even quicker (bigger lateral forces). If you still have the heads off you could consider the Guzziology idea of arming (and enlarging) the valve ends by putting Ducati shims over them. Hubert Not planning on removing the heads in my case, and so I guess my choices are 1) grind/polish to remove the pits (not sure how much material can safely be removed - Hubert?) 2) replace the rocker assy ($$$) or 3) re-install and keep an eye on clearance for any further wear ... very tempted to go this way! Based on the pics, it looks like Bjor's rockers have experienced greater wear than mine (and in significantly less km's) and so I would ask the same question as thumper re what clearances were used..? Of course this could just be a production/batch issue and not related to clearance. I've always used the clearance given by the factory, 0,10 mm in and 0,15 mm out. However, the bike had around 40' km on the clock when I bought it, and I don't know the settings of the previous owner. The strange thing is that all the other rockers are OK... Link to comment Share on other sites More sharing options...
luhbo Posted February 12, 2012 Share Posted February 12, 2012 ... 1) grind/polish to remove the pits (not sure how much material can safely be removed - Hubert?) ... No idea, sorry. I thought it could hardly become worse as it was already, and as the 2.option with the $$$s was not an option I just did it. So far (25.000km) all is fine. I will make a picture next time I look after it. Actually I'll loose a finger or two should I touch anything 'frosted' outside ... 3) re-install and keep an eye on clearance for any further wear ... very tempted to go this way! ... Definitely. There is not very much movement between the mating surfaces, so nothing bad should just fall out of the blue. Just watch it, now as you're sensitised for it. Next time you pull the bearing pin you might want to mark its orientation and compare that with how the pin itself is wearing. My experience says that these rockers always look like that after 'some' time. I had 4 or 5 engines over the years, all with 100.000 at least (never bought a new one so far), so I don't think it's really a matter of batch. Hubert PS: this mug has done 125.000km. Would be nice if I had a picture of it at 50.000 Link to comment Share on other sites More sharing options...
luhbo Posted February 12, 2012 Share Posted February 12, 2012 ... Do you buy your stuff from Stein Dinse, since you are located in Germany, or do you have any better suggestions...? No, normally not. Their China stuff usually is crap, and OEM parts you can get for the same money at HMB for instance (Guzzi only). Anyway, there's not much what could go wrong with these Duc shims, so why not there. Keep us posted, so far I only could read about it. Consider also the possible need to shorten the valves a bit to keep the kinematics at least in range (tools at hand?). Don't know how thick these shims are. Hubert Link to comment Share on other sites More sharing options...
Gio Posted February 12, 2012 Share Posted February 12, 2012 ... 1) grind/polish to remove the pits (not sure how much material can safely be removed - Hubert?) ... No idea, sorry. I thought it could hardly become worse as it was already, and as the 2.option with the $$$s was not an option I just did it. So far (25.000km) all is fine. I will make a picture next time I look after it. Actually I'll loose a finger or two should I touch anything 'frosted' outside ... 3) re-install and keep an eye on clearance for any further wear ... very tempted to go this way! ... Definitely. There is not very much movement between the mating surfaces, so nothing bad should just fall out of the blue. Just watch it, now as you're sensitised for it. Next time you pull the bearing pin you might want to mark its orientation and compare that with how the pin itself is wearing. My experience says that these rockers always look like that after 'some' time. I had 4 or 5 engines over the years, all with 100.000 at least (never bought a new one so far), so I don't think it's really a matter of batch. Hubert PS: this mug has done 125.000km. Would be nice if I had a picture of it at 50.000 Thanks for the advice. As far as losing a finger or two, normally this would be the case here also as the bike usually lives in the barn (and forecast for tonight is -14) ... but I rode him into the porch which has become the winter workshop. Closer to coffee / beer etc ... Link to comment Share on other sites More sharing options...
thumper Posted February 12, 2012 Share Posted February 12, 2012 The shims come in different sizes that is how the valves are adjusted and I think it is the opening shims you will need. Each valve on a duck has a opening and a closing shim. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now