courtesy of Jens Lyck

Kun for de teknisk langhårede - men også spændende læsning for andre. Mest på engelsk.

Engine strip (English)

Author: Pete Roper

All by Pete Roper - brilliant as usual :-)


Part 1.

OK, so let's start with the pretext that you've managed, by hook or by crook, to get the motive out of the frame and up onto a bench. All the different model types, Loops, Tonti's and Spines all come out in different ways and it's a pretty certain observation that the newer the machine the harder it is to extract the lump out of the chassis due to, especially since the mid eighties, the practice of adding more and more complex and un-necessary munt to machines and positioning even the necessary stuff in such a way as to make things harder than they need to be!

I'll be writing this from the perspective of doing a mid ‘70's to mid ‘80's carbureted motor but where I remember I'll add in stuff that is relevant to earlier or later models. The nice thing is that they are STILL essentially, the same, even the Breva 1100!!!!

Once the motive unit is separate from the bike it is probably wise to separate the gearbox from the motor prior to lifting the motor onto the bench, The motive unit is a sodding great bastard of a lump and while I, at age 50, can just about fling a *loose* motor from floor height onto a bench I really wouldn't recommend it unless you are keen on hospital food and relish the thought of some incompetent mountebank trying to push your guts back into your abdomen from your scrotum, (In the case of boys, girls I would really just say *No*.). Removing the box is pretty simple. Remove the starter motor and then the remaining six nuts around the bell housing. The gearbox should then just pull off rearwards but sometimes a couple of hefty blows with a rubber mallet will be needed to separate it as the clutch hub, if notched, will tend to hang up on the friction plate splines in the clutch.

Once the box is off pluck the thrust cup out of the centre of the clutch and pop it into a box marked ‘Clutch'. You'll be popping a lot more in there so make sure it's at least as big as the visible bits in the bell housing, ie, the ring gear, flywheel and other stuff that goes between the two. Since you're looking at the arse end of it anyway you might as well take the clutch to bits now. It is best if you use a compressing tool made from an old clutch hub with a bolt, washer and nut to preload the springs first as if you don't it's very easy to bend the intermediate plate when taking the whole thing apart. It isn't *vital* though as long you disassemble with care.

Using a 13mm socket with your 6 inch extension and a T bar break loose one of the bolts that retains the ring gear to the flywheel and remove it. You can now get a piece of flat steel plate about three inches long with a couple of holes drilled at each end and hook it over one of the bell housing studs before putting the bolt through the hole at the other end and screwing it back in about half way. This will conveniently lock the flywheel so you can then break loose the rest of the bolts with little effort. Once they are loose remove the ‘Tool' and then undo all eight ring gear bolts in a crosshatch pattern a couple of turns at a time. As you do this the ring gear will be pushed backwards, (Unless you're using your home made clutch compressing tool.) and eventually the ring gear will pop off. Remove the bolts, followed by the ring gear and then fish out the two friction plates and intermediate plate, noting that the raised side of the centres of the friction plates face BACKWARDS. This IS important for re-assembly.

With the friction and intermediate plates out the pressure plate can be removed. If the machine ahs been in service for some time the splines in the flywheel may be well clogged with dust making the extraction of the pressure plate a right frontbottom. Give it a spray with brake cleaner and poke around the splines to loosen up the dust and wriggle the plate it will eventually come out followed by a cascade of clutch springs, eight in most cases but on 1100 Sports and Hi-Cams there will be ten! All of this horrible gubbins can be put in the ‘Clutch' box and put aside for ‘Ron', that's ‘Later-Ron' . For the time being the flywheel itself can be left on the crank as it is a great aide to turning the wretched motor over. At this point find the ARROW on the outside of the flywheel and, after removing the spark plugs, turn the motor over with the flywheel until the arrow points to one of the small cast-in tits in the back of the bell housing in line with the centerlines of the cylinders. It doesn't matter which one for now. Use your ‘Locking Plate' between the flywheel and a bell housing stud again to prevent the crank from turning.

Now spin the motor through 180 degrees so the front of it is facing you.

Sitting in front of you will be the alternator, sorry, it's gotta come off. On later models with the Ducati alt you remove the stator by undoing the three 4mm allen bolts and simply pulling the stator off the rotor. You then undo the big nut on the end of the crank, remove it and the washer underneath and the rotor will simply pull off, or it should. Any problems and give it a start with your 2 jaw puller, being carefull not to damage it of course. Usually though they just pull off. With a Bosch or, (I think?) Saprissa type rotor the rotor is retained on a taper. To remove the Bosch stator requires care. It too is retained by three 4mm allen bolts but once they are out care has to be taken in removing the stator as the brushes which run on the slip rings on the end of the rotor are fairly fragile. Wriggle the stator off carefully and make sure that the back brush doean't get hung up in the gap between the slip rings or it will be prone to fracture. To remove the rotor, undo and remove the bolt from the centre of the rotor. This threads into the end of the crank BUT there are ALSO threads in the nose of the rotor itself inside the slip rings. Once it comes loose from the crank it has to be pulled back and then wound out of the threads in the end of the rotor too. Once out a piece of hardened 5mm NO BIGGER bolt or ground off allen key about 2 & 1/2 inches long can be inserted into the end of the rotor, (Always start off with a bit too long, it's easy to grind more off but once it's in there, I it's too short you're stuffed!) the bolt can then be wound into the end of the rotor and it presses against the key inside which in turn presses against the crank. Wind it down tight and if you're lucky the rotor will simply pop off, If not, a sharp rap with a hammer on the end of the bolt will usually suffice to cause the rotor to pop off the end of the crank. Be prepared to catch it! It's quite heavy! Once the rotor is off it can be placed inside the stator and put to one side in a box clearly marked ‘Alternator'. In the case of the Saprissa and Ducati alternators this is vital as unless this is done the rotor will loose it's magnetism and won't work when re-installed.

With Loopframes which have a generator in the V of the cylinders the belt cover should be removed and the pulley disassembled to allow removal of the belt before the gebnerator is lifted off the top of the block from it's saddle, (Which will quite likely be broken anyway! ) If I've got that wrong I'm sure Greg or someone will correct me, I haven't got a lot of loop experience.

One last step before we start opening the motor up is to remove the dostributor on models that have one. Undo the 'C' clamp bolts that hold the distributor in place and swing the clamp out of the way. On Loops, undo the 10mm bolt in the slot that allows you to move the distributor for tiing purposes, and lift the dizzy straight up and out of the block. Pop it in a box marked 'Distributor' along with the bolts, spacers, washers etc. and file in a safe place.

Orlright! That's got most of the extraneous shite out of the way. Tomorrow you can start getting dirty


Part 2.

Next step is to actually start removing bits of the *outside* of the motor itself. Probably the easiest way to approach things is to start with the timing chest at the front. Now the alternator is off there is nothing hindering the removal of the cover on later machines but on loops the big nut that retains the pulley mount has to be undone and the mount removed. In most cases this will slide off as the shaft is a straight one, not tapered, but if the machine hasn't been taken apart for a while it may require some persuasion with a small puller. After this the 14 allen bolts, (6 longer ones in the lower holes, 8 shorter ones in the upper.) can be removed and the timing chest cover removed. The gasket can sometimes be a bit sticky so prying gently between the fins at the bottom of the timing chest and the sump can be done but CAREFULLY, if it doesn't want to come there is something wrong, go back and double check you have ALL the bolts out and look for anything else that may be preventing the case moving. On later model Spineframes there are no fins on the bottom of the timing chest cover. In this instance though a few light taps with a rubber mallet to the crescent shaped part at the top of the chest, (a hangover from the loopframe days when the generator was mounted there.) will break the seal and allow the chest cover to be pulled forward and off.

As with ANY occasion where a part that seals oil in with either a gasketed face or simply mates flush and is sealed with some form of gasket sealer you should NEVER, EVER, EVER try to prize the two surfaces apart by forcing something, (Usually a flat bladed screwdriver!!!!!) between them and levering!! If parts won't separate there HAS to be a reason, there are very, very few instances in any situation where raw, brute force is needed. Prying and gouging with screwdrivers and the like will only lead to expensive and irreversible damage! YOU HAVE BEEN WARNED!!!!!!

Note also that Hi Cam motors, Centauro's, Daytonas and the MGS01 differ here in that they have the pulley and belt system on the front of the motor to drive the in-head camshafts. For now I'm not going to go into the differences on the Hi Cams and will concentrate on the pushrod models.

In the case of models with a mechanical tacho drive and my beloved automatics the tacho drive will roll off it's drive threads on the end of the camshaft but it is wise to try and pull the case off evenly to avoid stressing the teeth on the drive pinion. On the Auto's, as the case comes off it will expose the allen key drive for the pump in the end of the camshaft. Pluck out the key and place it safely in your next box, along with the timing chest cover, in a box marked ‘Timing gear.'. You will now see, exposed in front of you, the timing chain and it's sprockets or in the case of early model loops, a train of three gears. The large gear/sprocket at the top is the cam gear, the middle one is the crank gear and the bottom one is the oil pump drive. On the top cam gear/sprocket there is a 27mm nut which is what you will need to fit a spanner or deep socket on for the next stage of the disassembly.

For now though the timing train can be left where it is. Next stage is to pull the top end to bits!

First up, you can remove your flywheel holding tool, it's served its purpose for now. Next it's of with the rocker covers, most people will of already been here to set their valve clearances, the covers are retained by eight 5mm allen bolts, (note I'm using the size of the key to be use, not the thread size of the bolts here.). A light tap with the handle of a screwdriver may be necessary to break the seal of the gasket and then the covers can be lifted off and put to one side. One thing that is VERY convenient is that the rocker covers are just the right size for putting all the rocker gear and head retaining stuff in as you take it off, if you have a model without left handed and right handed covers, (As identified by the position of the breather lines to the rockerbox.) then mark each one with a felt tip pen with an L or and R so the parts don't get mixed up. Now to disassemble the rocker gear it is important that the piston be at TDC compression so that both valves are closed. This means there is no pressure on the rockers and achieving it is done exactly the same way as if you were setting the tappets, only it's easier because you can turn the engine using the camshaft nut!!!! Using your spanner or ratchet and 27mm deep socket turn the cam nut ainti-clockwise. This ensures the crank is turning clockwise which is how it turns when it's running, when viewed from the front. Start with the left hand cylinder and turn until you see the inlet valve on that side open and shut. You now know that you are coming up on the compression stroke. Using the arrow on the flywheel as a guide keep turning until arrow lines up with the tit in the bell housing and you know you're now at TDC compression. Double check by grabbing the rockers and giving them a pull up and down, youi should be able to detect a tiny amount of play which is the valve clearance. If there isn't any play then you are probably 360 degrees out and have made a mistake. Try turning the cam back and forth a few degrees? If the rockers and valves move this will confirm you're on the wrong stroke but if you have followed the previous instructions you should find you are at the correct point in the cycle. Another quick check is to spin the pushrods with your fingers. If they spin you're on the correct stroke!

Before going any further it is worth cracking off the locknuts on the tappet adjusters and loosening the adjusters themselves by a couple of turns. The reason for doing this is that when you come to re-assemble the motor, if the heads have been serviced the valves will sit slightly higher in the head. If you haven't loosened the adjusters you may well find that the rocker spindles won't slip back in through the rockers!!!!

Once everything is nice and loose the two 10mm bolts that retain the rocker spindles can be removed from the upper ends of the rocker carriers. Note that they also have spring washers on them. Don't loose them and if you need to get new ones, (Sometimes over-enthusiatic tightening leads to stripped threads on the bolts.) make sure the bolts purchased are exactly the same length. If longer ones are used they will block off the flow of oil to the rocker spindles and the top end will squeak and wear out super-quick!!!! After this you can push out the rocker spindles, a flat bladed screwdriver can be used in the end of the rockers to wriggle them out and once out the bolts and spring washers can be screwed back into them for safekeeping. The rockers themselves can now be lifted out of the carriers but BEWARE. At the top of the rocker closest to the part of the carrier where the retaining bolts for the spindles go there is a spring. On roundfins there is also a brass washer between the spring and the carrier, on squarefins there is a steel washer next to the carrier, then the spring, then a brass washer and also, at the other end of the rocker another brass washer!!!!! If you just hoik the rocker out the spring will go ‘Sproing' off into some dark and inaccessible corner of the workshop and the washer will go everywhere and you'll forget where they go!!!!!. Use both hands and lift the rocker out containing the spring and then round up the washers. Assemble the whole sorry business onto it's respective rocker spindle and pop it in the rocker cover. Repeat with the other rocker. Now they are out of the way you can withdraw the pushrods from their tunnels in the head and barrel mark ‘em with your felt tip pen I for inlet and E for exhaust and pop them into your rocker cover too.

To repeat the proccedure on the other side simply turn the motor over using the cam nut until you see the timing marks on the cam sprocket/gear and the crank sprocket/gear line up facing each other, (On the sprockets they are two stamped in lines on the front face of the sprockets, they aren't hard to see.). Once that is done the right hand cylinder is at TDC compression. you can then repeat the valvetrain removal proceedure you just followed for the left hand side and pop that lot in the right hand rocker cover.

Now go and have a cup of coffee


Part 2A.

Whoops. I'll have to proof read things a bit better. I've actually goofed up on the description of which side to start on here, you should do the right hand side first, (as seen from the saddle as it were.) and then go on to the left side last in the interests of using the cam timing marks to line up TDC compression on the left cylinder.

People might also wonder why I suggest removing the rocker gear on both sides before tackling the head on the first side? the reason for that is that if you pull the head and barrel on one side first then the rod will just flop about as you're moving the crank to TDC for the other pot. This can lead to damage of the piston skirt so it's best to leave the heads on until both sets of rocker gear and valvetrain are out and stored.

Anyway, I'll continue this this afternoon but currently Jude is hogging the internet connection.


Part 3.

OK, where were we?

That's right, we'd got the rocker gear out, now it's time to get the heads off.

The heads themselves are retained by six nuts. Five of these are obvious, there are the four that clamp the rocker carrier down to the head/barrel /case but there are also two short studs, one just below the spark plug 'ole and the other one which is the one that novices often miss which is in a coresponding position but at the top, or inboard, of the cylinder and head. This isn't immediately obvious because it's hidden underneath a plug that sits centrally, and just inboard of the rocker carrier. On all but the very early models this is a flat, chromed, plug with a 10mm allen hex in the top, this in itself is purely a blanking plug that stops the oil escaping from the rockerbox, the head nut itself is a sleeve nut underneath this plug. Very early models have a very large Hex headed plug.

To remove the plug you need a 10mm straight allen key and a socket for it to go in PLUS, in all probablility, a sodding great breaker-bar! The plugs are steel and screw into the aluminium of the head and are sealed with an o-ring. because the bottom of the plug and thread is exposed to the atmosphere, water and, in the case of people who live in such places, salt from roads in winter will conspire to cause the plug to electrolytically corrode in place amking it a right bugger to remove! My solution, apart from using a LONG breaker bar, is to use a large, flat ended, punch and an 8oz hammer and I'll go around the perimiter of the plug giving it a few sharp raps with the punch and hammer. No, you don't whale into it like Thor forging thunderbolts, just solid raps. This will help break the corrosion seal and makes it a lot easier to remove the plug.

Once the plug is out there is one more thing to do before removing the head. The rockers have an oil feed from a fitting in the middle of the valley of the motor between the cylinders. On roundfin models this feed goes to the front of the cylinder heads where a banjo fitting screws onto the front of the oil gallery that feeds the rockers. On squarefin models the feed was re-located to the middle of the head closest to the centreline of the engine. While early models simply require the removal of the banjo bolt to separate the pipe from the head the squarefin models have a straight, threaded fitting that screws into the head and the feed screws onto this. Due to the proximity of the head fins it requires a pair of thin, 14mm, open ended spanners to undo the pipe from the fitting in the head. These can be bloody tight and some care is required when loosening it as it's easy to slip and it is possible in these circumstances to damage a fin! Once the pipes are disconnected from the heads the central banjo bolt that connects the oil pipe to the block can be removed, (13mm banjo bolt.) and the pipe itself lifted off. Once it is off the engine grab the hoses and try and turn them on the 'Y' shaped fitting that bolts to the case and try and turn the ends where they go to the heads in relation to the hose. If the fittings turn in the hose order a new one now as sure as eggs is eggs the old one will leak when it is re-installed!!!!

Once the oil feed is out you can tackle removing the head. Using a 17mm socket and a short extension for the four rocker carrier nuts and the one by the plug 'ole and your long 10mm allen key and socket on the sleeve nut under the (now removed.) plug loosen the nuts in a crosshatch pattern. They are done up to 32 ft/lbs so you should need to use a bit of effort but not so much you fart! Common sense should prevail. Don't be too surprised if, on older models or ones from harsh climates, the stud that the sleeve nut attatches to unwinds from the crankcase rather than the nut coming off. This isn't an issue, you can tackle that later, it's not a disaster it just means the nut has corroded to the stud.

When the pressure has been relieved from the studs spin off all five hex nuts and the sleeve nut and remove them, (If the sleeve nut doesn't want to come out of it's recess leave it there, just remember it's there before you invert the head once it's off!) Under the five hex nuts there are flat washers that can be plucked out with a magnet, stick these into the rocker cover with the nuts and the rocker carrier that you can now pull off the four central studs. there is *supposed* to be a smaller washer under the sleeve nut. Sometimes it's there, sometimes it isn't. In any case it's a right cow to remove so I'd leave it in place and just be a ware to look for it once the head is off.

At this point there is nothing mechanical left holding the head on. What you will find though is that on the four studs underneath the rocker carrier there are squashed o-rings sitting in reliefs in the alloy around the studs. Before you attempt to remove the head pry thes o-rings out with a pick or small screwdriver and discard them otherwise they jam the head on the studs.

At this point you can slip your fingers into the inlet and exhaust ports and try lifting the head up on the studs. If it is reluctant to move give the head a few biffs with a rubber mallet but ONLY around the exhaust studs and inlet port. Don't biff the fins, they'll simply snap off! The gasket seal betwixt head and barrel is really quite weak, once the two move in relation to each other it should be a simple matter to pull the head up the studs and off the engine. If you haven't yet managed to extract the sleeve nut now is the ime to invert the head and wiggle the nut around until it drops out through the blanking plug hole in the head. Place the sleeve nut and it's washer, (if visible or even fitted!) in the rocker cover along with the rocker carrier for that cylinder and store in a safe place. The head also can, for now, be put to one side while you repeat the operation on the other side of the motor!

Once the other head is off make sure each side is suitably labled and stored safely somewhere clean and dry until you can return to the heads for servicing.

You'll probably want to stop for a beer about now.


Part 4.

OK, so where were we? That's right, we'd got the heads off.

From here, how I proceed varies from model to model but to keep it simple I'll suggest that the best thing to do is remove the timing gears/sprockets.

Using your flywheel locking tool again secure the flywheel so the crank cannot turn. Once this is secure you can use a deep 27mm socket to undo and remove the camshaft nut and remove it and it's washer. Then the 13mm nut that retains the oil pump gear/sprocket can be removed. Note that this nut is special in that it is an 8mm internal thread but is of a 1mm pitch rather than the usual 1.25mm pitch that is the ISO standard. I have no idea why. Under the nut is a lock-washer. this too can be removed. This leaves the crank nut. On all models prior to the 1100's the crank sprocket is retained by a peg nut. This is a circular nut with four cutaways in the sides which requires a special tool to remove and re-install. Nine times out of ten, if the bike has ever had it's cam chain replaced, this nut will show signs of butchery as most people and indeed many bike shops don't actually have a suitable tool and have resorted to using a hammer and drift to remove the nut and re-install it. While I would never recommend this practice it should be noted that probably at least 50% of all older Guzzis on the road have their peg-nuts, (There are others on the bike.) done up this way. I leave it to the reader to make their own appraisal therefore of whether the practice is truly likely to have terminal consequences if it undertaken.

For those with a bit more mechanical sympathy the choice is a bit harder. Guzzi themselves produce special box-spanners to fit these types of nuts. The thing is that in my experience the Guzzi tools are unremittingly awful, difficult to use and will tend to break with little or no provocation after a few uses, (And sometimes even on the first use!). Luckily for the Guzzi community a Scandinavian lunatic by the name of Rolf Halvorsen has put into production a set of Guzzi special tools, including peg nut sockets, that are absolutely superb. No, they ain't cheap but for anyone who is serious about working on older machines or even maintaining their own bike as a consumer durable, (ie. not throwing it away in a few years and buying a new one.) they are a 'must have'. I can't give them sufficient praise.

That being said the nut is locked with a tab washer that has fingers, one of which is bent up into one of the peg slots in the nut. Prior to removing the nut this locking tab has to be knocked flat to allow installation of the tool, (Or the biffing off of the nut with a sharp punch and a BIG hammer.) Once the tab is flattened I recommend heating the nut and nose of the crank with a blowtorch, (No, NOT the Oxy!!!!!!). Although both nut and crank are steel heating does seem to make removal of the nut considerably easier than trying to do it cold, especially if some moron has previously been in there and used red, or worse still green,(Shudder!) Loctite on the nut. Don't worry unduly about how much heat you put into it, it is unlikely you'll be able to damage anything with a Butane torch so just heat it till the oil starts to smoke a bit, install the tool and using a breaker bar crack the nut before winding it off. DON'T burn yourself!!!!!! If you do opt for the 'Brute force and ignorance' method make sure that the punch that you use in the peg slot of the nut is flat ended but not as sharp as a cold chisel. The nuts are a sacrificial item designed to fail before the crank threads if over-tightened and are in fact quite soft. If you *have* to bash the nut off, and even ifyou have the tool this is sometimes necessary if the nut has previously been butchered, make sure that the punch or drift you are using is engaged with the peg slot at an angle where it won't slip off and then give it a BIG, MIGHTY, WHACK with the biggest hammer you have in your armoury. Pissing about with weedy little taps with little hammers will only result in rounding off the peg slots and making the nut harder to remove. One or two big whacks will loosen the nut and allow it to be spun off relatively easily. Note that I DO NOT recomend this method of removal but sometimes needs must!!!!

Once the nut is off the lock washer can be removed and all three retainers and their respective washers cam be bagged, labled and placed in a box marked 'Timing gear' or some such.

On the 1100's the peg nut has been replaced with a conventional 32mm nut with a flat washer underneath it. Although at first this would seem to make things easier thre is a problem in that a.) the nose of the Ducati alternator equipped bikes are much longer than those of the earlier Bosch and Saprissa fitted machines which mans if a socket is used to undo the nut it has to be very, very deep. And b.) The clearance between the outside of the nut and the inside of the sprocket is quite small. most conventional sockets have wall thicknesses that are far too great. My solution to this dilema is to of ground down a 32mm offset ring spanner so it will fit over the nut and I retain it in place so it won't slip off by using a deep socket large enough to fit over the outside of the ring that can then be held in place by the alternator retaining nut. No, it's not very elegant, but it works. The alternative would be to buy the ridiculously priced Guzzi tool or make something up of my own. Being a skinflint I'm happy with my system!

Removal of the gears or sprockets is next. Models with gears are, in my experience, the most problematic.

The very early models that had gears used an oil pump with a straight shaft onto which the gear is pressed located by a woodruff key. For some reason these seem to seize in place over time and the gears reall, REALLY don't want to come off sometimes. The gear itself has two small threaded drillings in it for the installation of a puller. The thing is they are tiny threaded holes only something like 4 or 5mm in diameter. since the gears are often dificult to remove I'm loath to try and use them, even if I did have a suitable puller. In my experience it is fat better to use a small 2 or prefferebly 3 jaw puller on the outside of the gear but even with this it is sometimes necessary to exert considerable force and ue considerable heat to get the oil pump gear off! Quite often when they do let go it's with a BANG! like a pistol shot. Be prepared to jump out of your skin!!!!! Once the gear is off rescue the woodruff key and store it somewhere safe, they just love to disappear!

Both the cam and crank gears usually pull off without too much grief. Just check that they DO have timing marks before you remove them. The gears can them be stored in the 'Timing gear' box.

On models with a chain and sprockets all three sprockets have to be removed along with the chain as one unit. Sometimes they will slip straight off, sometimes you have to start 'em moving with a puller. Try to resist the temptation to pry at them by levering against the side of the timing chest, all you'll end up doing is damaging the mating surface for the gasket! Once they are loose on their shafts, (On chain equipped models the oil pump shaft is tapered.) all three can be wriggled off easily. Once again rescue the oil pump woodruff key and store it safely. There is also a key in the crank but for now it can stay there as long as it's in tight, (They usually are.) and the cam sprocket is located by a peg which usually will remain in the cam but sometimes will come out with the sprocket. Check where it is and DON'T loose it either!!!!!!

Once the sprockets are out of the way, on FI models it will be necessary to remove the 'Phonic Wheel' which is the crank position sensor triggering device that looks like a big cog with two teeth missing that sits behind the cam sprocket. This is also a good time to remove the pick-up from the outside of the case if it needs to be removed for any reason.

After this the cam chain tensioner can be removed. on earlier models this comprises nothing more than an 'L' shaped bit of bent steel with a nasty rubber rubbing block on the end. it is retained by two 13mm bolts that fasten it to the inner wall of the timing chest supported by two spacers. This so called 'Tensioner' is one of the most horrid things ever invented by man or beast. I suggest that as soon as it is unbolted you run, (don't walk!) to the nearest rubbish bin and deposit it therein forthwith!!!! DO NOT though throw away the spacers it sat on, they are REALLY handy for when we get to rebuilding bevelboxes!

On later models the tensioner was vastly improved to a spring loaded flapper type which is retained by two bolts again, one of which is also a main bearing retaining bolt, This too can simply be unbolted and stored in the 'Timing gear' box along with the phonic wheel.

So now the cam timing stuff is out of the way it is time, at last, to remove the sump. Before you do this make sure that the dipstick has been removed and that the oil really has been drained! The engine can now be placed flywheel down but with the wheel supported on blocks so that the crank, which is no longer retained at the front by the cam sprocket and nut, doesn't move rearwards and impose a side loading on the connecting rods. This will allow the 14 bolts around the edge of the sump to be removed. On early, pre oil filter models, the sump can now be removed. If it's sticky give it a few taps with a rubber mallet or dead blow hammer, being careful not to damage the fins. These early bikes also have 'Skid Rails' to protect the sump that come off with the sump bolts. As it comes off be prepared with a load of rags as there will be residual oil that will drain out messily, mop it up as you go.

With oil filter equipped Tonti framed bikes there are a further four, longer, bolts in the fins of the underneath of the sump. These too must be removed before the sump, and in the case of those bikes with one fitted, the spacer can be removed. On the 'Broad Sump' models, Sport Corsa's, V11's etc. the sump including the plate that covers the oil filter can be removed after which a further 18 bolts connect the oil filter/thermostat mounting plate to the crankcase, the extra four being in the same place as the four hidden in the fins of the earlier Tonti framed bikes as, like those, their purpose is to clamp the oil delivery galleries to the front and rear main bearings. Once they are out the oil filter/thermostat mounting plate, with those parts still fitted, can be pulled free from the bottom of the crank case. Clean and bag up these parts and put them safely to one side for now, we'll return to them later. Oil filters can at this point be removed and discarded!

Returning once again to the early, pre oil filter models. Rather than having oil delivered to the front and rear main bearing journals by galleries cast into the sump and drilled and oil being picked up through a gauze screen in the sump, these engines have a pick-up witha gauze strainer on it that bolts to the back of the wall of the timing chest and pokes down into the sump. This pick-up and it's strainer are held to the wall by, (From memory, I'll have to clarify this.) three bolts, two of which are also bolts that retain the oil pump from the front to the wall of the timing chest. These need to be removed to allow removal of the strainer and pick up. Once that is out of the way the delivery pipe that takes oil from the oil pump to the rear main bearing, retained by 4 x 13mm bolts with locking plates, can be removed. Note that this pipe also incorporates the oil pressure relief valve on these models.

Now all that nonsense is out of the way, labled and stored the engine can be briefly placed upright again so that the flywheel locking tool can be removed allowing the crank to be turned. This is necessary as the next step is to undo the big end bolt nuts and to do that the crank has to be moved slightly for each side. Pop the engine back on its flywheel supports once the locking tool is removed and then, by moving the block in relation to the crank, get the crankpin in such a position that you can get at the big end nuts. On early models these have locking plates that need the tabs knocking down to allow fitment of a socket. Later machines have castelated lock nuts. The 1100's all have bolts that screw into the rod from beneath rather than a nut and bolt set-up. All three designs are different though with the early bolts being different to the middle period ones and NOT interchangeable.

Once the nuts/bolts are undone on one rod the crank can be repositioned slightly to get at the other rod. Once they are out the caps of the rods can be removed. Make sure they are marked left and right. The engine can now be placed back in the upright position and first one barrel and then the other can be pulled up the studs and off the crankcase. As this is done, hopefully, the rod will separate from the crank and the whole assembley of barrel, piston and rod can be withdrawn. The reason I choose to do it this way during a full engine strip is that it lessens the chance of the piston being damaged while the barrel is off if the crank is being turned. I know it is unorthodox but I have my reasons which I will endeavour to explain a bit later.

On models that DON'T have anything in the way of the rod nuts, ie Tontis with an in sump oil filter, I always remove the barrels and pistons/rods before I remove the timing gear. Why? Because it obviates the need to support the flywheel as the crank is still supported at the front by the crank sprocket. It saves a lot of farting about.

Once the barrels are off the rod and piston assemblies can be pulled from the barrels and the rod caps for the respective rods re-installed and loosley attatched. Do NOT mix up the rod caps or which piston assembley goes in which bore. Wrap them up and put hem aside for now while we finish the engine strip.

OK, It's quarter to four in the morning here. I'll leave it there for now.


Part 5

And as they come out of the turn it's 'Bludging Slug' by a head from 'Waste of Space' who seems to be faltering. Behind him comes the pack led by 'Running Scared' closely followed by 'Blinking Soddomite' and 'Puckered Anus' who seems to be finding his second wind! At the rear we have 'Election Promise' who is running a close race with 'Masturbator'... Whoops! Sorry, my previous career as a race caller getting the better of me there!!!!!

Where were we? OK, We now have the rods out. Once they're out of the way the block can be stuck upright again and the oil pump removed from the front of the timing chest. this is secured by 4 x 6mm allen bolts, (On earlier models at least one of these will of been removed to allow the removal of the oil pick-up and screen.) Once they are off the pump can we wriggled off. Sometimes a few sideways taps with a tiny hammer will be needed to loosen it as it is located with dowels that can be reluctant to move. DON'T wallop it!!!!! Just a few taps to un seize it and then grab the shaft and rock it until it comes off. Bag it up and put it to one side, being careful not to let the bearings or inner race fall out.

Next on the list is to peel off the old cylinder base gaskets if they are still on the block, (sometimes they stick to the base of the barrels.) and extract the cam followers. It is very important NOT to get these mixed up as they waer to match the lobes of the cam they run on. I always get a small cardboard box and make four slits in the top and mark them LI, for 'Left Inlet', LE, for 'Left Exhaust' etc. and then push the inverted followers into them before storing carefully somewhere where they won't get knocked over, mixed up or whatever. after they are out the three 10mm bolts that hold the cam retainer plate in the timing chest can be removed and the retainer plate taken off. Note that the bolts have lock washers on 'em. Don't loose 'em. Once the plate is off the camshaft can be withdrawn from the block, bagged and put with the followers. plate and bolts.

That, essentially, only leaves the crank!

Turn the block around and lock the flywheel. Now undo the sis 13mm bolts that hold the flywheel to the crank and discard them, (We'll go into why later.) The flywheel can then be taken off the back of the crank leaving only the crank and main bearings in-situ.

The rear main bearing is reatained by eight 13mm bolts. These can be undone and removed. The problem is that removing the rear main bearing is a bit of a sod. It is a very tight interference fit with the crankcase and doesn't like to move. There is a Guzzi special tool which is essentially a threaded puller that screws into the two bolt holes at 1 and 7 O'Clock on the bearing flange, (These holes in the flange are threaded to 10 x 1.25 to take the puller bolts. The 13mm bolts that retain the bearing have an 8 x 1.25mm pitch.). The centre bolt of the puller then bares against the back of the crank so the bearing can be wound off. The problem is that even with the special tool the bearing is so tight in the case that it is possible to snap off the bolt lugs on the bearing flange before the bearing will start to move, needless to say, you don't want to do that ! The bearing isn't cheap!

By far the safest way to remove the bearing is to press it out using the crank to do so. Now, few home mechanics will have a hydraulic press handy but this is one of the tasks I would encourage people to take to their local garage or engineering shop that DOES have one. it is a very, very simple and quick operation, most decent shops will probably do it for a sixpack, or nothing, simply because they'd be interested!

After you'be ascertained that the bearing isn't going to just slide out, (I haven't had one do so yet!) place the crankcase on the press in such a way that the nose is below the hydraulic piston so that it will bear on the end of it. Place the supports in such a way that the rear main bearing flange will clear the supports as it comes out, ( at all times keep your hand, (Or your mates hand!) under the crank ready to catch it if it suddenly falls out.). Now, place a small hard wood block on the nose of the crank and and while you hold the rear main bearing flange from underneath use the press to push on the nose of the crank. As you do so the crank will press on the rear main bearing, (Don't worry, the shape of the front edge of the bearing and the radius of the crank mean that NO harm will be done to either.) and it in turn will be pushed out of the block.


Once the crank and bearing are free of the block lower them gently until you can grasp the webs of the crank and carry it to the nearest bench. It'll be oily, so hang on tight! Once you're at the bench you can grasp the crank by the crankpin and pull the rear main bearing off the back. DO NOT LOOSE THE OIL FEED DOWEL THAT SITS IN THE GALLERY IN THE BEARING THAT GOES TO THE CAM SHAFT REAR BEARING. This is a small tube who's purpose is to locate the bearing itself into the flange that bolts to the crankcase. Failure to install it when the engine is rebuilt can lead to expensive and embarassing damage!!!!!!!

That leves only the front main bearing and the cylinder studs in the case!

The front main bearing is retained by 6 x 13mm bolts which can be removed nd the bearing extracted. Usually the front main will simply pull out by hand. Note that it too has a locator dowel in the housing to lock the bearing, don't loose it either!

While removing the cylinder studs isn't strictly necessary I always do because it allows me to clean the gasket surface thorougly with a gasket whizzer and whetstone which ensures no leaks when it goes back together.

So now you have a bare block and a selection of parts, some still partially assembled like the rod and piston assemblies and the oil pump.

From here on I'm going to deal with these parts as separate units that will each need separate overhaul before the reassembley of the engine takes place but for now you can breathe a sigh of relief and take some pride in the fact that you've managed to get the motor completely disassembled without, hopefully, breaking anything!!!!!!!!


(PS. If youre interested the race was won by 'Bludging Slug' because they always do, 'Running Scared' was always a good bet for second. 'Puckered Anus' and 'Blinking Soddomite' were a photo for third, inseparable, and as expected 'Election Promise' came to nothing as is always the case.)

Part 5A.

Whoops, It just occured to me that I overlooked a couple of things.

  1. Early, pre '84 models have an oil return pipe that takes oil from the condensor back to the sump. This is the smaller of the two pipes that poke out of the top of the bell housing part of the crankcase. Irritatingly this can't be removed with the flywheel in situ as it rund arouund the inside of the housing, behind the flywheel before returning the oil through a large banjo fitting with a long combined bolt/pipe that pokes through the case at a 45 degree angle into the sump. Once the sump is off this pipe will prevent the block sitting flat on the bench so you have a choice. Either you can remove the flywheel, remove the bolt/pipe and then remove the return pipe before loosely re-installing the flywheel or you can choose to support the block on a couple of lengths of 4 x 4 wood so the pipe doesn't foul on the bench while you're working on the motor.
  2. The large breather pipe that pokes out of the top of the bell housing is also bolted to the inside of the back of the crankcase inside the bell housing. Unless there are signs that it has been leaking I strongly suggest you just leave it alone! There is no need for it to be removed and once they have been and are replaced they are remarkably leak prone. Post '03 bikes don't have this breather as it has been moved forward to the back of the timing chest.

Sorry about that.