I've written this ages ago and finally decided to stick it on the website in case somebody would actually want to read it...
One word of warning straight away: these bikes are - in the words of Donna Versace 'high maintenance but not expensive'. While not in the same TLC league as an older Ducati (also hailing from Bologna), negligence that Japanese bikes tolerate would slowly but surely kill a Morini.
The information here is only really applicable to the V-twin Morinis (3 1/2 and derivates). Older Morinis, while sometimes available in the UK, are much rarer and spare parts are generally not available as easily as for the later Models. All Morinis however provide their users with enjoyable handling that is at least on par, if not better than their contemporarys. This mainly results from a well-designed and very stiff frame. If the frame seems bent, walk away...
The good news are that these bike are very robust compared to their Italian peers. This does not mean that they are as unburstable as some Japanese or German bikes but they tend to rack up mileages that can make Ducati owners weep. Also, most parts (save for some body parts on the later models, especially the Enduro models, Kanguro and Camel) are readily obtainable and Morini wrenching does not require a degree in mechanical engineering. But Morinis require the user's willingness to forget about some learned wisdom and learn to think 'the Morini way'. More about this later.
I originally wrote that Morini engines are working well on super unleaded fuel. However, with more long term experience in running these engines on super unleaded it has been noticed that while these engines run well on super unleaded for a while they'll eventually suffer. The consensus now has changed to run them on super unleaded with an appropriate lead substitute. Personally, I've had good experiences with Castrol Valvemaster which is available both with and without an octane booster.
Oil changes are extremely important to the health of the engine. These engines do not have paper element filters; they have a nylon(?) mesh filter that is just about good enough to stop conrods from floating about in the oil stream. The workshop manual advises that oil changes should be carried out every 4000km/2500mls or every 10,000km/6000mls when using Castrol RS synthetic. As I heavily use my Morinis in town I usually change the oil every 2500km/1500mls. It is not important to use the more expensive bike oils as Morinis have dry clutches; I tend to use a high-quality car oil, usually semi-synthetic. Opinions on the correct viscosity are divided but as Morini specified 20W50 for summer use and 10W40 for Winter use, most UK owners I have spoken to tend to use a good 15W50 or 10W40 oil in our colder climate.
Apart from very regular oil changes, the long-term health of the engine depends on the owner's right hand. Careful warming up the oil (2.5 litres on the smaller engines, 3 litres for the 500cc engine) is the key to a long life. Once the oil is hot, there is no problem with revving them up to the red line (and keeping them there) but don't try this with the engine cold.
Fortunately there aren't many. The usual suspects (i.e. the electrics) are responsible for most of the problems. Given a choice, try to avoid bike with wiring harnesses that seem to be modified with lots of pre-insulated connectors. The electrics always look like a bowl of spaghetti but 'helpful' owners can make it a lot worse and the only long-term solution then is a rewire of the whole bike. Connectors that are burnt out from oxidation should be replaced by the proper non-insulated variety and as many contacts as possible/accessible should be cleaned on a regular basis.
The electronic ignition system is usually reliable. However it is very much different from other systems of this type and does not suffer unknowing owners or AA/RAC patrol men without wiring diagrams gladly. Keep in mind that the system does not use battery power; it takes it power off a separate system on the flywheel. The beauty of this system is that you can start and run the bike with a totally flat battery. The only problem that seems to be getting more widespread is that the system's transducers (coil modules) are suffering from drying out and subsequent breakdown of their insulation. As there are several types of transducers available and front and back cylinder transducers are not interchangeable, it is important that they are replaced by the correct type. The good news is that several people are able to either supply new transducers or repair the old ones.
With the exception of the Dart, the electric starters are a bit fragile and are often broken on bikes in the budget price range. To ensure longer start life, use the kick start when cold (all models but the Dart have a kick start) and only use it in short burst to minimize the risk of burning out the motor or starter clutches. As a well-maintained Morini should start on the first or second kick anyway this should not be too much of a problem.
Another common fault is a reluctance to start, If your Morini suffers from this, remove the carb's float bowls and check if the O-ring gasket on the choke jet (the one jet sitting in a corner and fitting into a hole at the bottom of the float bowl) has been squashed, hardened or is in general bad condition. Replacing the O-rings on both carbs usually improves starting to no end.
Nearly as important for the health of the engine as regular oil changes, the cambelt should be changed every 20,000km or 3 years, whichever comes first. Failure to do sure can/will result in interesting and expensive noises from the cylinder head area of the engine when the belt breaks and the pistons close the valves. Changing the cambelt itself is not a big task, but somebody decided to hide the belt behind the alternator flywheel. As this also controls the ignition and has the timing marks on it, careful disassembly and reassembly a very much the order of the day.
The last (widespread) problem is related to the clutch. As mentioned above the clutch on these engines is a dry clutch. Once the seal on the gearbox output shaft packs up (usually due to old age), the dry clutch turns into a wet clutch with predictable results. This shows up as a stuck clutch. The health of the clutch is easily assessed by pulling in the clutch lever on an idling engine. A distinct clatter should be audible in the clutch (lhs) area of the engine. Before you suspect a contamined clutch, though, check that the clutch actuation lever on the rhs of the engine has the proper play. It not, the result is a dragging clutch.
The clutch plates can usually be cleaned with paraffin unless badly soaked but the leak needs to be sorted. Of course the long-term cure is to replace the seal, but some owners have been going for years by keeping the oil level in the middle of the two markers of the dipstick and never, ever using the side stand. OB dipstick: make sure that your bike has the proper dipstick to avoid overfilling.
This is a minefield that I will try to cross as quickly and safely as possible. Keep in mind that the 350cc engines are in a fairly high state of tune already (Sport engines up to 42 hp at the crank) so tuning them further without turning them into high-revving time bombs requires a fair amount of skill and even more knowledge about Morini engines. The easiest way to more power at the expense of bottom-end power spread is putting in a hotter cam. Morini produced a range of competition cams with the 2+2 and L5 types being the most sought after these days.
Several kits are available to increase engine displacement. The most popular mod is to stick 400cc Dart pistons and cylinders on the 350cc engine (same bottom end). These parts are getting scarce, but NLM has a 375cc conversion that simply requires boring out the existing barrels.
The 'holy grail' of Morini tuning usually involves sticking the next size up engine into the smaller frame. Chicken Ranch Racing in the US used to put 350cc engines into the 250cc V-twin's frame. The frame being a lot lighter and physically smaller but as well handling as it's bigger sister's. The same goes for 500cc engines in 350cc frames. The bike that at least used to be the fastest Morini in the UK until a year or so ago has a highly tuned 500cc engine kicking out in excess of 55bhp at the back wheel in a 3 1/2 frame, finished off with some tasty Valentini parts. It now seems that another 3 1/2-500cc hybrid with a lightened frame has taken the crown.
In contrast to its more legendary Bologna competitor, Morini has never attracted as many authors. The best easily available English language book about the marque is Mick Walker's 'Morini'.
In the UK, spares and workshop manuals can usually be provided by North Leicester Motorcycles and some smaller specialists. All of them advertise in the Morini Riders club magazine 'A tutto gas'. You can occasionally find spares and bikes on the famous 'an Internet auction house', otherwise known as ebay.
The above mentioned club is also a good source of information; the membership cost can also be offset by the discount on parts that NLM offers to club members.
On the Internet, the most important resource for the enthusiast would be the Morini mailing list. The Dutch Morini club also has a very good and comprehensive website and a very useful technical section on the site. Fortunately for those of us who don't speak Dutch, the site is bi-lingual (English and Dutch). Their webmaster Tony Kersbergen also pointed out that my information regarding the use of unleaded fuel in Morinis was somewhat out of date.