I purchased my first MK III new in '83 from Agostinis. I had pre-ordered the bike for a European delivery and I was going to ride it around for a couple of months before taking it back to Mandello where they would crate it up and ship it home for me.

The Mk III was a bike in transition. It was the middle of the true Tonti Lemans series, the last of the 850s but it was the first of the square fins yet it was immensely successful for Guzzi with 10,000 sold.

It had striking angular lines, a formidable heritage from the original and MK II, and the largest white tachometer dominating the dash that I had ever seen on a motorbike. It has been written that many of the sales were due to that tacho.

It’s a Tonti frame big block and shares many components with other models of that era. Frame, electrics, brake system, wheels, drive shaft were virtually the same as many of the naked touring (T) or faired (SP) bikes yet there is enough to stand it apart. Many of the comments in this piece are relevant to all Tontis, not just the MK III.

It differed from its predecessors in a number of ways besides looks. The square fin motor not only looked more modern but it had more fin area for cooling but more importantly it produced 5 more hp. There was no real change to internal design but Guzzi had just improved machining tolerances with the new engine. The swing arm was a bit longer giving it a bit more high-speed stability and the solid rubber seat didn’t fall apart even though it didn’t provide any more comfort.

The MK III engine is considered by some as one of the best engines ever to be produced by Guzzi. It’s a mid valver with good compression. The valves are big enough to breathe but not too big to cause excessive wear and the PHF 36 lean burn pumper carbs give the bike enough fuel when it’s needed. In fact care needs to be taken at lower revs not to twist the throttle too quickly providing too much fuel for the start of acceleration.

At 4000rpm the engine is as smooth as a multi. It has another harmonic at 6000rpm but red line at 7700 prevents the next one at 8000rpm. Other models that I have ridden don’t seem to have this level of balance within the mill.

The bike was originally fitted with twin points but most riders have fitted electronic ignition. I still have my original MK III with points but my second has electronic optical pick-ups.

The timing chain adjuster, like all big blocks of the time was basic to say the least. An aftermarket spring tensioner improves things dramatically. My original bike is fitted with steel timing gears from Agostinis. Beware of after market or alloy gears. They have a nasty habit of chewing themselves to pieces but the originals, like mine are virtually impossible to obtain.

There were 2 gearbox options. The standard T helical box or the close ratio, straight cut ZD box. I had the option for either, the ZD being more expensive. I chose the standard box for one very good reason. The last thing this bike needs is a higher first gear and that’s what you got with the ZD. It also produced a real whine as most straight cut gears do. The ZD is now difficult to find and new parts are made of unobtanium. The flywheel is heavy and I like it that way. A firm foot movement and a bit of patience on the up change and a blip of throttle on the down change assists a smooth selection

The PHF 36 carbs are fitted with bell tops. This allows a faster throttle response but increases throttle resistance. Some find the action too hard so remove the bell tops and fit flat tops and new cables. Another option is fitting a throttle lock or palm rocker to alleviate the pressure and allow some rest. I’m accustomed to the action and really all riders need to do is to ride the bike and get used to it. For extra soft riders a couple of doses of medicinal “harden up” wouldn’t go astray. After all it’s a Lemans, not an automatic Piaggio scooter.

The bike can easily attain 5.5-5.8L/100km. The lean burn carbs don’t need to be jetted up unless you are a big fan of wasting fuel. The 25 litre fuel tank gives the bike a fantastic range of over 400km so comfort tends to be the cause of most pit stops rather than necessities. Air can be a bit of a problem in the tyres. Most air fittings available at a garage won’t fit in between the 300mm front discs and the rim but an angled adapter overcomes this issue.. The rear drive and 260mm rear disc achieve the same result on the rear. The linked brake system works well and the bike can be stopped hard in a straight line just using the foot lever.

The bike came standard with "snowflake" cast wheels. these were originally designed for tubed tyres but with a small modification for the valve stem they seem to cope with tubeless tyres quite well. This topic is keenly debated by those that think tubes are safer as that's what the they were designed for. I purchased a second hand MK III a number of years ago. I got a slow puncture in the front tyre one day. I was able to make it 40km to the next town with the last few hundred metres to the garage with them totally flat. I still needed a bead breaker to get the tyre off and to my surprise there wasn't a tube. I've run it like that ever since.

Original suspension looked good on paper. Air assisted front and back but the Paolis on the rear weren’t the best quality and when they expired rebuild kits weren’t available. There are quite a number of replacement options. I have had Marzocchis but I found them a bit stiff and prefer the Ikons that are currently fitted.

The forks are only 35mm and with the split front brake due to the linked system there is a noticeable twist when using the hand-operated brake. A fork brace alleviates this twist, if you put the recommended air pressure in them they tended to be too hard for the real world. Hit a bump in a corner and the damper would have trouble stopping the springs from rebounding. I now only put a few psi in them and find it an improvement.

On the road the bike likes to be run. Open country with sweeping curves is its best domain. I’ve commuted on the bike but it’s not really well suited. The forward lean limits visibility in traffic and with no wind resistance the weight on the arms and hands can become tiresome. The long wheelbase and steering geometry is suited to high-speed stability not wiggling in and out of traffic and the clip-ons limit the leverage for steering also.

I have listened and read comments about the switches, how they are unreliable and tend to break. Both my MK III’s still have their original switches and they all work. To add to this my '81 Monza has identical controls and they work too. They are different to most of the Japanese style switches of that era too but once you are accustomed to them they are no more difficult.

I have my second MK III set up for touring. Non-Fango racks and bags fit easily on the Tonti frame just as they would on one of the touring models. A Corbin seat, that is no longer available, really improves the rear end comfort and a set of flatter bars looks after the arms and wrists. The bars are easily fitted as the top steering yoke still came with the bar saddle hidden under the rubber dash. A couple of clamps from the wreckers, four bolts and the job’s done.

The side stand on the bike tends to lean it dangerously over especially if you ride on the left side of the road. When parking the bike it leans down into the gutter rather than up into the camber as it would in Italy. It can’t be lowered from the saddle either but again there are options to improve matters. I have modified the stand bracket so that I can lower the stand whilst astride the bike. This helps when loaded with gear and weary after 4 hours riding due to that 400km range.

A stable center stand is fitted which allows nearly all maintenance. I certainly wouldn’t buy a bike without one. All in all I can say the MK III is a reliable every day classic. With only minor alterations it can be the basis of a comfortable tourer or it can still surprise many with its handling and performance in sport mode. Oh, and they can still attract a bit of attention if your ego ever needs a boost.

Words and pics by Morizzi

Moto Guzzi 850 Le Mans III Technical specifications

Year	1981-1984	Final drive gearing	4.714
Bore (mm)	83	Box gearing: 5th	0.750
Stroke (mm)	78	Box gearing: 4th	0.869
Capacity (cc)	844.057	Box gearing: 3rd	1.047
Compression (:1)	9.8	Box gearing: 2nd	1.388
Valve type	ohv	Box gearing: 1st	2.000
bhp	76 (crankshaft)	No. gears	5
@rpm	7700	Front tyre	100/90 V18
Torque (Kg-m)	7.6	Rear tyre	110/90 V18
@rpm	6200	Front brake (mm)	d/disc 300
Starting system	Electric	Rear brake (mm)	disc 242
Oil system	Wet sump	Front suspension	telescopic
Valve timing	ohv	Rear suspension	swingarm
Inlet opens BTDC	20	Ignition system	coil
Inlet closes ATDC	52	Wheelbase (mm)	1505
Transfer exhaust open BBDC	52	Ground clear, (mm)	175
Exhaust closes ATDC	20	Width (mm)	640
Tappets, inlet (mm)	0.22	Length (mm)	2190
Tappets, exhaust (mm)	0.22	Dry weight (kg)	206
Primary drive gearing	1.235

Carburettor settings:

Dell'Orto type	Size	Main	Pilot	Slide	Needle	Needle Position	Needle Jet
PHF 36BS/BD	36	115	50	603	K18	3	265AB

Further Reading:

To read more articles and bikes featured click here to go back to the features index. Additionally you may also want to read about Rod's recently acquired California III. There is a further article on the Le Mans III submitted by Bob.

Squadra Guzzista is all about real Guzzis which are ridden by real people. Mahoosive thanks to Rod (Morizzi) for taking the time to put this article together!

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