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specially if the original price is scrap value.
I found this post from a fellow in NZ:V65 Lario was my introduction to the world of Moto Guzzi some 20 years ago My understanding of the valve problem goes like this:- The relatively heavy valve springs coupled with a somewhat soft material used in the valve stems, resulted in the ends of the valve stems mushrooming with use. This resulted in the valve adjuster being unable to slide on the end of the valve stem, causing the valve stem to flex back and forwards, eventually fracturing. This of course resulted in the valve heads dropping onto the top of the piston, destroying that side of the motor. The factory fix for the problem was the issuing of a set of hard steel lash caps for the valve stems. I fitted the lash caps, and also softer valve springs (Suzuki GN250). The motor seemed to be much happier with the softer valve springs. Fitting these caused a small problem, as the GN250 springs are slightly larger in diameter than the oringinal Lario ones. This was overcome in the following maner. I obtained spring retainrs from 2 different Suzuki models. From memory these were the GN 250 and a GSX250. One retainer was a properly machined steel retainer, that fitted over the valve guides and provided a seat against the head that matched the increased spring diameter. The other retainer was a pressed steel one (like a bowler hat) that also matched the increased spring diameter, but significantly was exactly sized to fit over the Lario spring retainer without any play at all. This allowed me to use the standard Lario valves and collets, as the collets were still fitting into the Lario retainers.
Gentlemen,I decided to bring a Lario back on the roadI have no issues with (the costs of) modifying the valve trainBut what then is the preferred route ?I believe there are quite a few very knowledgeable people around,but unfortunately their proposals, their results and the reasoning behind themdo not converge(in my limited understanding)I have a feeling that what is lacking is a solid description of the variables with regards to how the engine has been operated, combined with the modificationThing like generally high / low RPM, yes / no red line RPM, yes or no frequent use,long / short distances, oil quality, additives, etc.This especially keeps me busy, because of the followingI accept that the design might be flawed, that (too) many engines destroyed themselves,that eventually all engines will destroy themselves, but ..... why is it that so many last so much longer ?Kind Regards,Evert
@Chuck, @Huub, @Jackson,Thank you very much for your repliesCombined with the very well documented efforts of IceBlueI can see the multifaceted aspects with regards to the valve trainI have already found the "bible", Tuning for Speed; thank you @jacksonMy formal training is Chemical Engineering, but I will try hard to familiarize myselfwith the contentI also realize that as a start, I have to appreciate that the Guzzi engineers wereknowledgeable, and phrasing questions keeping that in mindOne of them:Why did Guzzi specify 0.10 mm gap for the Intake and 0.13 mm for the Exhaust, whereasthey increased this to 0.15 mm respectively 0.20 mm for the 2V's ?Could it be that these gaps have become "super critical" for the Lario ?When the valve train is so much higher, mechanically stressed, could it be that the dynamic behavior does NOT allow for any free play, before engagement of the components DOES take place(For example, I take it that Followers are called just that because they should follow smoothly)I have "seen" this issue of uncontrolled engagement being discussed in the context of sprag clutches that weredestroyed in no timeThey are / were in MV Agusta's !Thank you for your patience; you are educating a Guzzi enthusiast who wants to get a Lario back on the road,and lastingKind Regards,Evert
Dont expect guzzi to have engineered that much on the lario it was rushed into production to keep up with the performance of the rest of the market. to save costs parts were sourced from other models, even when it made no sense for this application (like valve springs, carbs, camshaft) it was just buit for a couple of years and wont be remembered as their best product ever. so current knowlegde of the valve system is from amateur engine builders. the guzzi camshaft is pretty crude, has no quitening ramps so valves are basically smacked open. i dont think a extra 0.05 mm will change a lot about that situation. i prefer to keep the tappets on the loose side, but that is just my personal preference
Hello @jacksonracingcomau,If you are looking for a RH cylinder head I have seen there is a used one aroundBUT, they ask 300 Euro !!Regards,Evert
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