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I reckon poor materials is a big part of the problem with the cam (12 and 14mm) not so much the design.
I've seen some big block camshafts that have the oil feed modded so it comes out on the lobes themselves....maybe this could also be done one the small block ones ????
Maybe Larios need to be "rollerized".
Staring at bits in front of me, not so much.
As Super Chicken says:You knew the job was dangerous when you took it..
I agree with much of what's been said.I reckon poor materials is a big part of the problem with the cam (12 and 14mm) not so much the design. What are the cam and followers made of? If poor quality steel is the problem has anyone thought about having a cam and followers made? This is what I'm thinking - pull the stock 12mm cam and followers as a pattern and have a chilled iron (or other durable material) cam and followers made by a specialist. Add to my existing one piece stainless valves w/lash caps.My machine has stainless steel one piece valves with machine matched guides and Suzuki GN250 springs. Might change the springs if I upgraded the cam and followers. Would this work or would it trash the pushrods or some other component?Whadya think Cheers
not sure you need the stiff original valve springs , the valves are lighter, the rockers heavier but there are two sets of springs operating one rocker. the original lario valves were made from some steel , and were magnetic current guzzi valves are stainless, only the hardened tip at the top is magnetic
Oe valves i have here are 2 piece, stainless head with ferro shaftMagnetic right the way to headCan you tell me where ss valves with hard ferro tips came from ? I would use these
stein dinse: bought a couple of weeks ago.https://www.stein-dinse.biz/Moto-Guzzi/Engine/Valves-guides-springs/Exhaust-valve-24-0mm-V65-Lario::8677.html
i was going to change the exhaust valves as a precaution , so did not order inlet valves. never seen those fail anyway. i already run these valves in the lario, the current exhaust valves have no real wear on the tops , and are run without lash caps i might try elefant foot adjusters to reduce side loads on the valvesthe vespa scooter adjusters look promising, just not sure the threads match the lario rockers. the valve train of the lario and V75 is pretty identical, they had the same issue's
8V's use similar adjusters. They come with two different thread pitches, not sure offhand what they are but they simetimes cause consternation if the correct pitch isn't chosen. Check the pitch on the Lario.
I'll have a dig. Early adjusters have a lot in the top for adjustment. Later ones a 3mm Allen hex. As mentioned they have different threads.WRT the roller tappets I'd be very, very surprised if they use a different tappet, at least dimensionally, in the V85. It simply wouldn't make sense. Somewhere in Michael's shed there is a cracked cambox off the 1400 that's going in my Stelvio I'll send the entire cambox down as it's easier to see how the whole tappet is aligned with a guide roller if you have the cambox to examine with everything in-situ.I have early adjusters I think. Not sure about later ones although the 1400 rockers are later type. Be patient please as since Michael's crash I'm not only busy but as far as his workshop is concerned I'm flying pretty much blind so the bits will take a bit of digging out.
You know that flat and roller tappets require completely different profiles? If I just send down a cambox complete you could start with the current 8Vprofile as a starter if you graph it or take it to a grinder with the ability to custom form a master.It's not probably the best profile for anything but mapped up, (Or jetted for you Luddite!) correctly it can and does deliver a very nice midrange punch. Scale up or down to suit.My guess is that the V85 will essentially follow this trend although I expect it to be an interim motor if Guzzi continues to follow precedent and I can't see the spivs in charge of the current project moving far outside the box.Pete
I am watching this tread with interest.I have a Lario that I saved from a wrecker due to dropped valve.I took the heads to a Brisbane based cylinder head guru and he was not impressed with the design.He reckons there were lots of issues with the design.Spark plug placement and lots of alloy shrouding it and shit porting on both intake and exhaust.Closing pressure on the valves was over the top with the standard springs.Anyhow I put it back together using a set of IceBlue's valves, Lash Caps, Yamaha Adjusters, Nevada Springs.We did a quick clean up of the ports to suit the standard 30mm Dellortos and manifolds.It runs standard Lario pushrods and a 14mm cam. It also has a Dyna S ignition system and Enduralast charging system.I have done about 5,000 klm on it since the rebuild and so far so good.Its a great bike to ride. I have not exceeded 8,500 rpm so far.I am in the process of building up a PX750 motor to go into a modified Lario frame.For this motor I have used ceramic thermal dispersant coatings.I have two sets of heads for it. One set is much modified by the Bribane cylinder head guru with bigger valves, better springs, much porting and 34mm carbies.The second set of heads are set up for the Stein Dinse valves, lash caps, Yamaha adjusters etc.This motor also has a 14mm cam and I will be running a Ignitech ignition and Enduralast charging system.Both motors run a 2 into 1 exhaust.I am very keen to share my findings and learn of others discoveries on these PT and PX motors.CheersBruce K
The fun is in doing it first, please do send cambox complete, have man very close who knows more about cams than most, developed all for modern cars, loads of race stuffHe can make master from bb one, modify as needed or go proper mental, give me 12k peak !Not sure if you have latest details, pm sent address etc
Only issue I can see is getting the pushrod located on the top of the tappet in the block. The 8V's use a hemispherical 'Pad' on top of the tappet shaft that engages in the rocker. The top of the tappet tower is flat. This will obviously be a non-starter with a pushrod arrangement. I'm imagining the V85 will have some sort of 'cup' on top of the tappet for pushrod engagement?If you're hoping to see 12K out of it you'll be needing to beef up the rods big time or they'll snap like rotten carrots! What will the MEPS be at 12?PS. Found a cambox off the 1400 and am waiting for info from Michael on the whereabouts of a set of earlier rockers. I have a later adjuster, can't find my thread gauge but it looks like it might be 0.5mm. Earlier ones are coarser so might be 0.75. As soon as it's all together I'll post it off. Please don't loose any of the bits.
I followed up with him last year and the bike was reliable and fast for (IIRC 30 000) miles and still is (with a different owner)HTHCheers
So here's some stuff from Moto Guzzi Club GB magazine 1990, written by Simon Howers. He bought a 4 valve V75 brand new in 1986 and sorted it out with help from Raceco (UK); the aim being to make it reliable up to 10 000RPM. Not sure the overrevving/coil bound spring issue has been raised here before?- On strip down the cam and followers were stuffed after 3000 miles with serious damage to the lobes- Guzzi fitted a single coil spring that which at full valve lift is within 1mm of being coil bound- ...not only that but each spring requires about 50kg to depress it- the springs have two effects, they place incredible strains on the cam lobes and secondly a slight overrevving of the engine would cause them to slam open, and break the head off the valves- Larios have the same problem and show alarming signs of wear after about 20000 miles.A new standard cam was fitted with Kawasaki 500/4 springs. His view is either cam is fine and the springs are the problem, the later 14mm cam is a Guzzi bodge.I followed up with him last year and the bike was reliable and fast for (IIRC 30 000) miles and still is (with a different owner)HTHCheers
expert fixed syptom, ignored cause.
This is not the first expert that has done that. And that is strictly *not* inclusive to motorcycles.. <shrug>
amazingly my lario survived 40.000 miles with the stock valvetrain, after the first engine dropped a valve i fitted a spare engine ( with soft springs and stainless valves. )that one is going fine too ( probably close to 40,000 miles on it too, but so was the original engine )
