READERS’ FREE ADS
A few interesting machines this time, including one of Frank’s old motorcycles…
the Guzzi twin needs fuel and reliable sparks to run. So those are the first areas to check if your project Guzzi doesn’t! Our intention was to continue detailing and sorting the chassis, wiring and connectors, so we made room by stripping the engine of its exhausts (which need to be removed in order to unbolt the lower fairings), carburettors, the sump and its extra spacer.
A plain bearing design, the Guzzi twin motor depends greatly on its high pressure oiling system. The filter coming loose is one thing you’ll wish to avoid, and keeping an eye on the top-end oil pressure line is a service priority. Satisfied with the condition of the rubber elbows and the hi-zoot Ago breather they connect, we removed the alternator cover to access the hex on the crankshaft’s nose to rotate the engine.
Backing out the screws and pressure line banjo fittings, the cylinder head covers come off, exposing the rockers and adjusters. Finding top dead centre with a wood dowel on top of the piston insures both valves are fully closed, allowing for a check of the tappet clearances. I debated pulling the rockers to re-torque the heads, but with little to no leakage on the gasket I left them alone. The lock screw adjustment is easy but necessary, as the engine will not idle smoothly if valve lash is not properly set.
It’s debatable how many big Guzzi twins still fire their plugs with the original contact breakers, but here’s one which hasn’t swapped to a more modern system. Yet. The key to very long life is keeping a fresh battery installed and limiting use of the ignition switch for starting only. Adjust fully opened on the ignition cam and oil the lubricating felt. Just slightly dirty, the faces looked new after a shot of contact cleaner and a quick polish with emery paper.
Taking stock, with the chassis sorted and the driveline serviced it was time to address the grimy Dell’Orto pumpers and install the battery. It was here that time and the unsavoury remains of old fuel had done its worst. The accelerator pump buttons were locked solid and the rest was stained with varnish. Rebuild kits are available for most Dell’Orto sizes, and after a thorough soak
in PB Blast penetrating oil we methodically replaced every O-ring and gasket, including the choke plate. Our custom cable maker took a try or three, and the bike would benefit from a proper Tomaselli ¼-turn in place of the cheesy plastic throttle. Another earlier upgrade is the Delrin intakes, which restore the solid mounting of the carb/filter that was lost with the long-discarded factory airbox. Guesstimating equal slide lift with an always accurate finger method, the leads were attached to the battery, the K&N pods squeezed into place and the exhausts bolted back onto the engine.
Like most road-going vintage Moto Guzzis, the SP is sharp but not overdone. I recall clearly how the SP looked when my brother Nick rode it home 37 years ago, and to be honest the bike isn’t that difficult to keep in good mechanical order. If the check valves are working then the crankcase and transmission breathers are active, and the best way to keep the oil inside is to replace worn crush washers wherever you find them. Cosmetically, details count. You can see the Guzzi’s mismatched factory paint in the photos, but replacing minor items like the rubber grommets that attach the side covers and keeping the steel barrel inside the rubber bodywork washers allows those parts to seat correctly for a tight fit.
While on the subject, behold the rattle-can magic adorning the SP’s chemically-ravaged frame. Investing years to perfect my method; I scrape, sand or wire brush away the damaged paint until reaching an unaffected area, then wipe it down with paint thinner. This one was down to the bare steel in spots, and after taping and masking I blend misting coats using the same barbeque heat paint I point at the exhaust. When everything is even, a clean towel is used to buff the almost dry surface to return the same semi-gloss finish which Guzzi sprayed in Mandello. Sure, the compliments are nice and I’ve even been asked to ‘restore’ others, but the real bonus is knowing that the inevitable scrape to follow is no cause for despair.
Much has been said about the failings of Italian electrics, but I’d had no major problems during the last forty-odd years of Guzzi ownership. So it came as a surprise when the SP’s starter relay flashed (shorted) on the initial stab of the button, and the starter remained silent. Confirming that voltage was reaching the switch and starter, we bypassed the circuit by jumping across the solenoid with a screwdriver and… nothing. MG Cycle once again exchanged parts for a credit card number, and the replacement solenoid fit into the SP’s original Bosch unit perfectly.
Thus equipped, the SP jumped to life instantly, ending a long hiatus. A tank of fuel and a few laps around the garden warmed the engine enough to synchronise the carburettors, and the Twin Max carb tool is a pleasant surprise after years of using mercury
tubes. It’s powered by a 9V battery. The rest of the bodywork was carefully cleaned and installed, with normal fussiness like adjusting clutch free play and tweaking the shifter/ exhaust interface being happily carried out.
What caused the starter failure? I’m still not completely certain, but Alex did note that of the five Guzzi twins living inside our workshop, the SP was the only one running without its factory solenoid cover.
It’s now ready for whatever life on the road may throw at it: our one goal of returning this old Moto Guzzi to its former reliable self has been met. There simply isn’t room to list every step we took to safeguard its dependability, but details like insulating control cables at wear spots and fixing a hose clamp around the oil filter to keep it from coming loose are old school lessons learned from experience.
I simply must tout the benefits of mixing Marvel Mystery oil in the fuel. In addition to being an excellent top-end lubricant, the Marvel additive saved us from many frustrating tasks, and the interior of the Guzzi’s petrol tank was virtually spotless. Specialty items like bodywork and badges are becoming increasingly difficult to find, and the costs of vintage Tonti frame parts have skyrocketed in recent years. Happily, there’s a worldwide network of firms offering spares and advice, exemplified by websites such as Gregory Bender’s ‘This Old Tractor’ and other enthusiast locations overflowing with trouble-shooting techniques and advice. Unless your project Guzzi is mangled or suffered some other kind of mechanical abuse, the work is fun and even therapeutic, rewarding the caring owner with thousands of carefree, character-packed miles.
Rear drive splines. The new one is on the right…
Above right: Handy piece of kit for those who prefer to balance their own carbs: the Twin Max carb balancer
Left: Cleaning and greasing the steering head bearings
Replacement cush drive rubbers are usually a good idea
Above: The engine was basically fine, and a poke around inside the rocker boxes found no disasters
Job done. Time to try it out
It is essential that wheel bearings and spacers are fitted in the correct order
If you’d ever wondered what an ‘Agostini breather’ looked like, well, this is it!
Above: Moto Guzzi Spada, eclipsed by BMW’s tourist twins, but a very fine machine in its own right Above right: Cosmetics sorted, the Guzzi’s ready for a longer life Above far right: Admire the neat – and very period – instrument layout