Why did Larios drop valves ?

[Chuck in Indiana]

I reckon poor materials is a big part of the problem with the cam (12 and 14mm) not so much the design.

I'm not so sure of that. Back in the day, MegaCycle made cams for the Lario, and they failed, too. I still don't think anyone has the definitive answer. 

[Frenchfrog]

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 ????

[Chuck in Indiana]

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 ????

My understanding is that MegaCycle did that..

[Antietam Classic Cycle]

Maybe Larios need to be "rollerized". 

[Chuck in Indiana]

Maybe Larios need to be "rollerized". 

I've heard of worse ideas. <shrug>

[jacksonracingcomau]

Maybe Larios need to be "rollerized". 

Should only be a few weeks to see roller tappets in new v85, possibly worth waiting for, would cost a lot to make one offs. Of course, case may be radically different and not fit anyway.
Other possibilities include modding oil feed to camshaft.
However it goes afaik camshaft/ valve tip etc wear is intrinsically linked to valve dropping issue.
Fix main issue first, if I can, proper head scratching going on in oz.

If anyone in world has a high mileage, used hard sb4v, I'd love to see pics of tappets.
Used hard important, treated like heron head v7 they will last same.
Think I got sucked in a few years ago, esp Mike Wrenn's late v7 with 4v heads, all made sense at time.
Staring at bits in front of me, not so much.

[Chuck in Indiana]

Staring at bits in front of me, not so much.

As Super Chicken says:
You knew the job was dangerous when you took it.. 

[jacksonracingcomau]

As Super Chicken says:
You knew the job was dangerous when you took it.. 

Even  super chickens know flying is the easy part, it's staying up that bothers them and me

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

 

First, measure the lift you have with cam now, dial gauge on rocker over pushrod
Report back also pics of your lash caps/ adjusters
Where did valves come from ?
If they were uk made g & s, all i ever bought from them were nitrided, as they should be
But interested in yours anyway, hope they are 21/4N, do you know ?

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 shaft
Magnetic right the way to head
Can you tell me where ss valves with hard ferro tips came from ? I would use these

[huub]

Oe valves i have here are 2 piece, stainless head with ferro shaft
Magnetic right the way to head
Can 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

[jacksonracingcomau]

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

Thx, look to be nitrided too, will get this week
Are inlets same, just ferrous tip ?

Don't suppose you've had them long enough to see if tip shows any wear ?
Valves in CiI engine worst wear I have ever seen, valve tips, adjusters and lash caps. all toast
But cam worn to nothing prob explains, super chicken before egg or somesuch.
Keeping the cam egg shaped is the big ask,
 tell me story of v75, all I have ever heard is they dropped valves immediately, one apparently straight from pdi / handover. That goes against what I see in these Lario engines, cam is first man out the door, valves follow like sheep.

[huub]

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 valves
the 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

[jacksonracingcomau]

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 valves
the 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

I'm onto the ktm elephants feet, should see one this week
250/400/450/520 etc etc all use same thread
Wil post part number when I know, also how much room, may need rocker pedastial lifting ?
Post if you find vespa ones too, may even be same part diffrent price

But did v75 wear cam to nothing quicker than v65 ?
More important, did they drop valves without wearing cam ?
As I'm studying bits, it's the camwear that drives all the other issues.
Light valve springs in mine & chuck's did nothing to save

[huub]

i was looking at these
https://ves-parts.com/02-klepstelbout-vespa-etlxlxvs-p-2232.htm

[pete roper]

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.

[jacksonracingcomau]

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.

Lifesaver Pete, thanks don't know how I missed that from all photos of 8v rocker gear you've posted
6mm x 0.75
If they survive follower failure on BB, they have proven worth. In sickness and in health !
If you have please post me some to check
Even if thread different, rocker arm may be modifiable
Repaid in beer on maiden run to spag, will detour extra few hundred miles to go via bungendore if you're not going. Doesn't hurt my detruction test either. Thing will sink or swim, never ever float around in some mediocre fashion.. fly or crash

[jacksonracingcomau]

Pete
One more thing to measure if you have a chance
Roller tappets, just occurred to me v85 may not have reinvented itself without a little help from bb 8v

Might be way off but if there is room to fit between centres, these could be the answer
Have cases/ barrels on bench, magicians not far away i

Thanks

[pete roper]

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.

[jacksonracingcomau]

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.

Mucho grarcias
Agree, why reinvent, guide should be doddle
Fingers crossed this is the answer to all, no need to nitride or dlc cam, if fact if it works I reckon I can get fkd 12mm cams buit up with stellite, grind a proper grind, let some ponies free
Rollers can deal with big bumps, swhy queen sits in one on potholed London roads !
Elephant's feet will cure the valve drop, I think, scars on valves and adjusters are telling me a story.

Feel like a kid waiting for xmas

[pete roper]

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

[jacksonracingcomau]

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

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 stuff
He 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

[650TT]

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.

Cheers
Bruce K

[jacksonracingcomau]

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.

Cheers
Bruce K

Hey Bruce, best feedback I have seen since all builds of 5 years ago.
Definitely keep comparing notes, all I have is worn bits, be first time I actually built one.
What I don't know is how long it take cam/followers to start breaking dowm, or even if it is just an oil thread, no zinc on flat tappets blah blah.
Rollets, if I can make them fit, should take that part out.
As you say, many other things to do to make them work but I am doing first gently to prove, also have two engines, second will be more, but I'd like 10k km looksee on #1 before actually testing #2
Very interested in your headman, did he measure spring pressure ?
My engine with Nevada springs has caps/collets I could not use, collets stick out a mile
Do you know which caps you used ?
Also installed height, I will need a bit more pressure with weight of rollers but also trying to get rockers to spin freerer so may not be far off.
Same for your springs with big valve, pressures, at installed height and full lift
Caps with them ? Availability from your man ?
My best help in this is cam genius, if we can be certain we have solved cam wear and valve dropping I'll go with his ideas, he has done this a lofetime, now sold business and retired but can't stop getting his hand's dirty, loves a problem.
I can see a sb4v aus owners group meeting coming up, hope both of us make it there !

[pete roper]

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 stuff
He 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.

[jacksonracingcomau]

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.

Ta
Will show all to cleverer man than I, nothing is impossible only cost thereof might outweight value
12 is for nuther day, maybe, for now safe 8500 forever would be sweet.
Just trying to put the pin back is all
If pad that works rocker not in  it, just send me pic or link to on here , bet you've posted it altready

[Simmoto]

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)

HTH
Cheers

[huub]

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)

HTH
Cheers

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 )

[jacksonracingcomau]

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)

HTH
Cheers

Thanks, actually sent Amadeo an email recently when I was in uk, asking if he had ss lario valves but no reply. He used to buy ss valves for bb from/with me, together we bought enough to get price right. I never wanted to play Lario then, 30 years have changed me.
Still don't know if had lario ones made, vague memerry says yes.
Agree with all, valve spring pressure tester on my horizon but first I want roller tappets.
Part number for these springs would be handy
My lario has 80k km on clock but know it blew once before, I think cam never changed, expert fixed cause maybe but ignored major symptom
Maybe catch up uk next summer ? Would like to see this v75 but picture of valve gear would tell all, if no wear on valve tips/adjusters we have to say this one was fixed.
Assuming it has been given berries for 30 years of course, 10k rpm is working

[Chuck in Indiana]

expert fixed syptom, ignored cause.

This is not the first expert that has done that. And that is strictly *not* inclusive to motorcycles.. <shrug>

[jacksonracingcomau]

This is not the first expert that has done that. And that is strictly *not* inclusive to motorcycles.. <shrug>

Sorry chuck I modified that as you were replying, he may have fixed cause but not one of symptoms
There are a few symptoms here, valve dropping the one in title, but cam is up there.
Mud is clearing, a plan is forming, when I get Pete's rollers I will know more
Might paint it tartan
Bye bye baby baby bye bye................ ..

[IceBlue]

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 )

Read most of this string. I think what huub here relates is very descriptive of the Lario "issue". Having read a lot of report on when Lario drops valves point to more than one culprit IMHO. Some PX and PT mills only did a few thousind miles/KM before destroying cam lobes and dropping valves. Others did like 40-60.000.

The jury is still out, but a few pointers seems certain.

The PX and PT - or any other SB design was never intended for 8V operation. So the design is certainly not in favour of the valve train design of the 8V's. To make sure the mills would sustain hefty over revving, very stiff springs were used. About the same strength as the double spring of the early 4V SB's. NOW - some SB's with these double springs also occasionally dropped valves. The cam lobe here only had to lift ONE such stiff spring. Imagine - in the PX and PT engines the cam lobe had to lift TWO such springs initially on a 12mm lobe. In the late 80's Guzzi started using the progressive spring, and recommended all double springs replaced with this new spring at the same time Guzzi introduced the 14mm lobe CAM with that spring on all subsequent SB's. To my knowledge valve drops on 4V SB's totally vanished after that. I think they'll have a similar effect on the PX and PT 8V mills, although the lobes on the 8V's will have to lift TWO progressive springs.

I do not think this makes the PX and PT's bullet proof!! ...but I think it helps. IMHO, the following facts has a say in the problem.

- Quality of the material used to produce the camshaft and followers. (The huge variation in millage in when cam lobes are flattened - even on the same cam shaft - one seemed almost untouched - another basically flattened)
- Quality of the valves
- The VERY stiff stock spring - I swear by the V7/Nevada progressive spring - but this will limit the RPM to the red line - NO over revving
- The overall design of the modified valve train to accommodate 4 valve heads instead of two valve heads
- Oil used - make sure it has the ZDDP needed for flat tappet mills
- Cooling design of the heads - I'm not convinced though…

If you want to secure the PT and PX mills to the maximum level - wearing both belt and suspenders - but staying with the stock geometry of the train and still throw in the bucks it takes, I'd assume the following:

- Progressive V7 Classic/750 Nevada spring assembly
- One piece valves - pricy but needed
- Yamaha clearance screws - larger "face" hitting the valve stem/cap
- The later 14 mm lobe cam shaft
- Possibly DLC coated tappets and CAM - I don't know much about this procedure - some are not happy about the risk of diamond wear dust in the oil
- Good quality stem caps if required by the valve quality/design, to avoid mushrooming the stems
- Oil with adequate ZDDP for flat tappet mills
- Oil bush between cylinder and head - drilled to 2mm - stock 1mm - controls oil flow to the head and valve rockers. Oil also helps cool the head

The PT and PX will likely still not be bullet proof - but from what I learn "around the block" it helps a lot.
The adaptive design of the 8V valve train in the PX and PT mills will always leave one nail in its coffin.

One of my Lario's now has 18.000km on the clock with the progressive V7 spring and the 14mm cam.
Pulled one cylinder this summer to check the cam lobes, clearance screws and stem caps.
It all looked like the day I upgraded the mill - only just visible wear on the caps and clearance screws. 

The Lario is one fun bike! - makes it acceptable with a slightly earlier expiration date on the mill if its number is up 

Ciao