So you are thinking about an older small block and want to know what to buy or what to look for. There is a lot of misinformation about the small block V-twin Guzzi. Time and vague memories have conjured demons and rumours from both truth and gossip. There are quite a number of texts already out there so this piece isn’t designed to replace them, just supplement them with age related details.

This piece is a compilation of personal experience and information that I have been given or I read on various forums. It isn’t intended as a definitive text but a guide to assist the prospective owner. Just remember, these bikes are getting old and have had years under different owners. Who knows what history they really have and what faults lay hidden. Always remember, “Buyer beware!”

Firstly I’ll deal with the twin valve models. I’ll deal with them generally as I simply don't have the time to go into all the minute detail. I'm not going to differentiate between the 3 marks of V50’s for example. That is well documented already in the references listed at the end of this article.

Which small block do I want?

I’ve only owned V65’s but I have ridden V50’s. Both models are able to maintain road legal speeds all day long whilst carrying your self, a pillion and gear. The V35 was very popular in Europe due to registration costs for bikes. All the big names had 350’s including Ducati’s famous 350 single and the less known but highly praised Morini 3 ½. If registration isn’t an issue for you then why would anyone pick a 350 when the 500’s and 650’s are the same weight, same frame and same handling? If one is for sale locally, at the right price and suits your needs then by all means consider it but if not my suggestion is to go for the larger capacity models. The power curve is very even on all of them and none of them could be described as “over powered.” To substantiate this, where I live, even the V65’s are classified as LAMS bikes. That basically means that due to their power/weight ratio and engine size are legally suitable for learner riders.

There are standard models, touring models, cruisers and sport models to choose from too. The V35 and V50 came in a sport model, the Imola and Monza respectively. There are claimed horsepower advantages but in reality there isn’t a lot. The style and seating is altered though and this style of bike may suit. The real difference why a V50 can’t just become a Monza look-alike are the rider’s pegs. On the standard bikes the lower frame rails have the peg bracket welded to it. On the Imola and Monza the pegs come from behind the lever pivot, from their own peg position near the meeting of the frame members.

The V65 didn’t have a sport model instead there was the V65SP, a fully faired touring model. This machine is vastly under rated as a tourer. The fairing works well as long as your legs aren’t too long otherwise the lowers can be a bit encroaching.

The C or Custom range was in the cruiser style. V35’s, V50's and also V65’s. The later V65 was referred to as the Florida and it was replaced by the 750 Nevada. I haven’t ridden one of these models but basically it is just a styling exercise using all the standard base components. If this style suits your taste or physique then there is really no major difference from the standard models.


There are off road versions too. Both the V35 and V65 came as a TT or NTX road trail machine. The TT was lighter with little in the way of fairings but the NTX came virtually fully faired with a fuel capacity of over 30 litres. It was updated later to a 750 but as per the custom series there is little in the way of major differences to the standard models.

Finally in the late 80’s the GT’s came along. Again it was just the V35’s and V65’s that came in this form. They were produced at the same time as the Mille GT (1000). The Trentacinque GT(V35) and the Sessantacinque GT(V65) were released in either black or red with gold striping. The V35 was mainly for the European market and the V65 for export. There are some differences and you will find a review of the Sessantacinque in the “Features” section of this site giving specifics. Sessantacinque Review.

What are small block specific points that I need to check?

The small blocks are quite a reliable machine. Many of them are still rolling down the road over 30 years after they were produced but like all machines they have components that tend to wear or fail before others. The small blocks are about 50kg lighter than the big blocks of their day so that amount of metal and material has to come from somewhere. The original model V35's and V50's came with chrome bores. This lining has had a tendency to flake over time causing other internal issues so if you are looking at one of these it is a point to check. V50 II's had Nikasil bores and all later versions came with Guzzi's patented Nigusil coating.


Steering head bearings:
These are similar to push bike technology, a ball race with loose ball bearings. If they are greased and tensioned properly then it is unlikely that there will be an issue.
They do last for quite a while and I’ve never had an issue with mine but some owners insist on replacing them with a tapered bearing kit available from some suppliers. Just check for any notchy feel or uneven movement when the steering is moved from side to side.

Oil leaks around barrels:
There are only 5 bolts holding the barrels and heads on a small block where there a 6 on a big block. Because of this they are logically more susceptible to leaking around the join. I’ve heard this, I’ve read this but I’ve never experienced this. From what I can ascertain it is just a few bikes that this seems to afflict. Maybe its just when the 2 matching faces are at opposite ends of their machining tolerance or if someone hasn’t torqued them down evenly in the correct sequence. Most times if I find an oil leak it is one of 2 things. The rocker cover hasn’t been torqued down properly or the gasket is damaged and been re-used anyway or the breather hose on the inside of the rocker cover is leaking.

Valve stretch:
You may have heard horror stories about valve failure in the small blocks. I’ll deal with that a bit later in the 4-valve section but basically the 2 valve models can suffer from valve stretch. If the valves and spring tensions haven’t been set up right or wear on the valve seats has allowed hot gases to escape and cause a hot spot on the stems then the valves are on limited tenure. This isn’t an acute problem. I’ve heard of figures of 60,000km – 80,000km on a set of valves but I do know of one Monza that got 195,000km on a single set of valves. Many other makes of bikes don’t even get close to this mileage. From 1991 the double set of springs on the Nevada was replaced by a single outer progressive spring. As this spring is the same size as the earlier outer spring it is a recommended fix for all earlier models also but, like the 4 valve models, there isn't total agreement on this either.

Initially the valve gaps recommended for the small blocks were 0.10mm inlet and 0.15mm exhaust but both of these were later increased by 0.05mm to 0.15mm inlet and 0.20mm exhaust. Valve gaps (rocker clearances) are there to allow for heat expansion so that when the engine is hot the valves can still shut fully. It can therefore be guessed that this increase in valve gap was introduced to stop any potential flow of hot gases over the stem thus increasing the service life.

The 2 valve bikes generally give lots of notice that the valves are stretching. The valve gaps start to close between service intervals indicating that the stems are stretching. These should be set and checked on a cold engine at TDC on the compression stroke.

Gearbox noise:
The small block 5-speed gearbox is a joy to use in comparison to its big block counterpart. One of its strengths is that it is comprised of straight cut gears but the disadvantage of this is that straight cut gears tend to whine. After a while, when the hardening is a bit worn the box can develop a whine at around 4-5000rpm. I was told by a very experienced, small block mechanic that some bikes whine and others don’t. He has pulled noisy gearboxes apart at the insistence of their owners only to re-assemble them again with no changes.

The main issue with the noise is that it can mask other noises that may indicate a faulty bearing or other potential problem. I have one bike that whines and another that doesn’t. I find that about 30% oil stabiliser helps to quieten the whine down considerably.

Oil Through Gearbox Breather:
Initially 1 litre of 80W90 was recommended for the gearbox but it was found that the oil would escape through the breather at high speeds. To remedy this Guzzi reduced the volume of oil recommended to 0.9 litres. The perceived problem with this is that the box needs a full litre to help lubricate the higher gears and it is thought that this issue may contribute to the gear whine. Evidently later gearboxes had a deflector plate to assist in oil reaching the higher working surfaces but I have never dealt with one of these. I can't see it being a great advantage though, from the number of later fuel injected small block owners also reporting the gear whine.

There is a simple fix to the oil escaping by extending the breather so that there is a hose that is run higher. Any oil then returns via gravity. The only catch is that the original breather valve holds the selector detent spring so any modification needs to be the same depth in the threaded hole.

Universal joint:
The small block u-joint is a single cross affair but it is integrated with the drive shaft. Because of this it is expensive to replace as a whole. Replacement crosses are available as long as the splines are in good order. Regular greasing of the splines assists in a long service life.

The U-joint rotates enclosed by the gearbox casting around the output shaft. If a U-joint ever fails it can cause carnage in the cast alloy. These can be repaired by a good alloy welder but look for damage in this area. There is a mild steel bush that can be inserted there to help protect the casting.

Breather system:
Many of the bikes have had their original filter boxes removed and pod filters fitted to replace them. What a lot of owners don’t understand is the breather system that is connected to the filter box.

The purpose of the breather system is to return oil condensate to the sump. Without this a Guzzi engine would eventually pump itself dry of oil. The engine has a shared journal crank so even though the pistons are 90 degrees apart there is still a constantly changing volume under the pistons in the crank case as the engine turns. The volume under the pistons changes by about 70% of the engines displacement every revolution.

Early bikes only had a very small oil dowel feeding oil to the valve gear. The rest was supplied by the breather system. Oil vapour was carried up via the push rod ports to condensate on the inside of the rocker covers. This would then drain down to a ridge in the casting and there are 2 fangs that sit directly above the valves and direct the oil to fall on them. Later bikes the oil dowel was increased and the main oil feed is via that but the vapour system still works as long as the breather system is intact enough. Morinis of the same era used this system solely to lubricate the valve gear.

If the breather system is blocked off or restricted then the crankcase builds up pressure. This may cause the engine to leak from any of its joins and seals. At low speeds the breather will suck air in too as the pistons rise so it is a god idea to have the breather vent filtered. It originally vented into the clean, negative pressure side of the filter box. It makes me wonder if the removal or modification of the original systems and the subsequent reduction in oil condensate flow to the top end contributed to a shorter service life for the valves.

Sump Spacer:
There is a train of thought that because the small blocks only have 2 litres of oil in the sump and the big blocks have 3 that the small blocks need more. Firstly to assist cooling and secondly to hold more oil so low oil level won't cause an engine seizure. There are after market spacers that allow an additional 1 litre of oil. Neither of my bikes have one and I have no intention of getting one.

My bikes have never exhibited symptoms of over heating and I live in Australia. I also think that if I didn’t notice the first 2 litres of oil leaking out then what makes me think another litre will save me?

If it helps you to sleep at night then spend your hard earned money, but my 28 and 21year old bikes have coped so far without one. If one is fitted I don't know of any negatives besides a reduction in ground clearance, just make sure the dipstick has been calibrated correctly.

What’s better about small blocks?

Lino Tonti was the chief designer when the small blocks were designed. They came after the big block and incorporated some important improvements in design.

The small blocks are much lighter than their big block counterparts as I have already written but there are some other advantages too. The timing chain is virtually trouble free, the oil filter can be changed without removing the sump and the ignition pick-ups are directly on the end of the camshaft giving more accurate ignition timing.

The 4 valvers!

I’m not going to write about the Imola II or the Monza II. They had similar issues to the V65 Lario but were never imported to Australia in numbers. In fact I have never seen one in the flesh or known anyone who has owned one. The closest I have been is that a single Imola II was advertised for sale in Australia on ebay and it re-appears every so often. There are some 750/4's about but from what I can tell they are in bits too. I'll leave them alone also.

A friend of mine in the Army bought a Lario new. He really liked my white MK III LeMans so he bought a white Lario. It lasted 16,000km before the camshaft failed. There was a general recall and that issue was fixed. A hollow cam with increased oil flow replaced the solid unit. All the bikes should have had this modification done but they still have a reputation for “grenade” heads. The fact is the 4-valve system apparently self-destructs without warning unlike the 2 valve models that give ample notice. The valve heads fall off at high revs!

I’ve read lots of theories about how to fix them but I’ve become a bit jaded. On some forums a new “expert” occasionally arrives with theories and fixes. What I have gleamed is that many of the bikes have been hidden away in sheds for a lot of years with the owners too afraid to ride them. Some of these bikes seem to be appearing on the market now and then. Many of those writing fixes haven't actually ridden the bikes far enough to test their theories. One real problem is that there have been so many failures that certain replacement parts have become scarce. In Australia some parts are virtually unobtainable but the situation may be better in your part of the world.

Evidently the original valves were 2 piece, welded together and to attain the revolutions the valve springs were very strong. This caused the heads to eventually part from the stem with drastic consequences. Funnily when talking to race engine builders if I mention this problem they immediately say ”the springs are too weak, the valves aren’t closing quickly enough and so they are getting too hot.”

What I find amusing is that when I have mentioned the breather system oil distribution flow, it has been laughed at by Lario owners. They claim that it isn't necessary as the designers removed that feature so it was obviously unnecessary. There are no drip fangs on the inside of the 4V rocker cover. unlike the 2V covers. I have replied by asking "are these the same designers who designed the solid camshaft and valve train that keeps failing?" In my opinion, if ever there was a model in need of more lubrication and cooling to the top end, by any means, this is it.

Valves from a Suzuki 250N evidently fit the Lario. One fix I have read, from a small block fan, is that the newer Nevada progressive valve springs are used with the Suzuki valves and engine redline is reduced by 1000rpm. This is a similar fix to the 2 valve modification but with the use of different valves. The main advantage of the 4 valve bike is more performance due to higher revs being achievable. Remove this advantage due to fear of catastrophic failure and the question is raised, what's the point?

I have been informed that the original springs were so stiff that they would have been stable up to 12,000rpm and the Nevada modification should be fine up to 9,000rpm, well above the redline set on the bike's tachometer.

Here is a selection of other comments that I have cut and paste to illustrate the situation:

From a Lario owner:

!) I have had a Lario for 5.5 years - I didn't ride it for the last 3 years but
put 11,000 km on in the time I did. The speedo showed 47,000 km when I bought
it but wear in various areas suggests that it has been around the clock at least
once.

2) The valve springs are dual coils, and quite stiff as well. This is not the
original factory setup - I believe it was a factory approved mod flowing over
from the 350 4-valve motor. I had decided to stop riding the bike fairly soon,
since I was reaching the "magical" 100,000 mile mark.

3) Mario from Thunderbikes in WA (Oz) used to race one in the 80s after sorting
out the valve issues. He found that the factory springs were way too strong -
with smaller valves they had something like twice the valve spring pressure!

He use Suzuki GN250 valve springs with original collets and replacement valve
retainers at the top or bottom - now I am hazy. He regularly saw 9,000 rpm on
his Lario while racing.

4) Deciding I needed a "spare" I bought another Lario in September, which had
suffered a major blowup in the right head.

Both exhaust valves had lost their heads, the head itself was destroyed but
fixable if you are desperate (I am told).

What worries me now is this engine has had the soft valve spring mod yet still
popped at around 65,000km, maybe a little more since I believe the speedo drive
was faulty for a while.

5) There are stainless valves around which are supposedly better. I have one
and will get the rest of 2 sets, because I am keen to do both bikes. I have
stopped riding my Lario (which appears to have standard issue valves) because I
believe it could pop at any time. While I have a spare set of heads it is not
worth the risk

And a Guzzi mechanic:

Early ones had cam and follower issues but the biggest issue with them was that the factory simply doubled up on the valve springs used on the 2VPC models and the spring pressures along with the very thin stemmed and not very cleverly made valves coupled with the under-finning and therefore heat build up in the heads leads them to shed exhaust valve heads like confetti.

There are a number of suggested remedies, probably the most successful I know of is using Suzuki GN 250 outer valve springs and caps with the Guzzi collets. No inner springs.

Thing is that tyres for them are hard to get, (Although this is improving again due to the number of big scooters with 16 inch wheels!) and many engine parts are now as rare as rocking horse **** so keeping 'em on the road can be a hassle.

And an ex Lario owner:

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 original Lario ones. This was overcome in the following manner. I obtained spring retainers 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.

With these mods, there was never a problem with the bike, I even re-purchased the bike in the late 90's with the mods still in place. The bike is still going strong - in the hands of yet another owner.

As shown there are a few ideas on this issue and I'm not getting too involved with the differences but the Suzuki 250N features quite a bit despite the variance of which parts should be incorporated. I'm just illustrating that the problem hasn't come to a definitive conclusion as far as everyone is concerned and opinions vary.

Lario Wheels and Tyres:

The Lario and some other models run 16” wheels both front and back. The problem now is getting tyres, of the correct profile, especially for the rear. Some owners are buying front tyres and mounting them on the rear backwards. With a lot of smaller wheel scooters this may not be so much of an issue as it has been but it is something you may want to investigate before purchase.

A friend of mine, an engine re-conditioner, was repainting a Lario so he got the 16” wheels sent off for sandblasting. When he got them back he noticed hairline cracks at the spoke/rim join. His eyes were used to spotting cracks in cylinder heads so he saw them straight away. They were virtually invisible to the untrained eye though. He purchased another set of two wheels and sent them off. When he got them back it was the same thing, more cracks. Whilst this is a very small sample group I would like to point out it is a 100% failure rate for the wheels. Why they crack I don’t know but it is something to consider. Maybe there isn’t enough flex in the spokes of a 16” straight spoke wheel?

Finally and a disclaimer:

I hope I haven’t put you off purchasing a small block Guzzi. Remember I am focusing on “what to look for after 30 years of service” rather than “what’s usually good.” A very individual friend of mine owns an amazing Monza. Anybody who thinks that small blocks aren’t robust just doesn’t know of this machine. It is “used” beyond belief and it is often seen at a rally leaning up against a tree with empty Guinness cans surrounding it. It doesn’t have a stand, any leaning post will do but it just keeps running and running and running.

I really like both of mine and intend to keep them forever. These models are now over or nearing 30 years old so they have probably been through several, if not dozens of owners and have done unknown miles with unknown maintenance. I can only pass on known trends to you but a complete and thorough inspection of the machine can’t be recommended highly enough.

This article will never be complete. As I discover and learn more on these models I will edit the information accordingly.

Useful References:

Guzziology. Dave Richardson
Workshop Manual. Moto Guzzi
Owners Manual. Moto Guzzi
Parts Manual. Moto Guzzi
Illustrated Moto Guzzi Buyers Guide. Mick Walker


A special thanks to 'iceblue Dk' for proof reading and input on models I've not had direct contact with.

Further reading

V65 GT Sessantacinque / Nevada 350 / Touring on a Breva 750 / V7 Classic owner report / More featured bikes / Resources for Guzzisti /