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Bike Review - Posted 19th May 2014
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Moto Morini 350K Sport - Snap, Crackle, Pop

That's snapping castings, crackling exhausts and popping fuses. Martin Gelder's Moto Morini three and a half Sport cafe racer is almost ready for cartridge emulators to improve the Marzocchi front suspension...

May is the month of massive Morini missives. This time last year my 1982 350K was treated to a rebuilt clutch, had its swinging arm sideplay tightened up and suffered the indignity of acoustic wadding being stuffed up its megaphones before being thrown into the frantic fray of the Festival of 1000 Bikes at Mallory Park and then the more mellow Morini Riders Club trackday at Cadwell Park.

Two Trackdays, Two Tarozzi Terminations

Both track outings were great fun, but sadly both were also brought to a slightly premature halt by failures of the remarkably brittle castings that make up Tarozzi rearsets. Tarozzi is Italian for 'brittle', by the way (no it isn't). Both failed castings were my own fault. At Mallory the left hand footpeg mount snapped, probably as a result of me having tried to kickstart the bike with the footpeg still folded down at some point in the recent past, weakening the casting. At Cadwell the tip of the gearchange lever parted company from the rest of the bike when I had a walking-pace spill on grass. Both the bike and I went down very gently, but the gear lever stayed down.

Moto Morini 350K Early bath after the gear lever snapped

The good news is that I'd done about two thirds of the sessions on both days - so I didn't feel too short changed by my own clumsiness - and both parts were available by return of post from North Leicester Motorcycles for not much more than the chunk of Dural that I bought from the Festival of 1000 Bikes autojumble, with a view to making my own replacement footpeg plate. A future project, perhaps...

Moto Morini 350K Footpeg plate from Mallory, gear lever from Cadwell, castings from Tarozzi, Dural plate from autojumble

Baffles, Bettered

The Acoustafil packing had kept the racket from the shorty megaphones down slightly, but for the Morini Club do at Cadwell something a little more effective was required. The circuits operated by MSV - Cadwell Park, Oulton Park, Brands Hatch and Snetterton - have much stricter noise limits than Mallory Park, which might explain the troubles Mallory Park has had recently with its neighbours. They noise test all the bikes taking part, with limits of 105dB(A) on 'noisy' days like the Morini Riders Club event and just 98dB(A) at some roadbike only trackdays.

Moto Morini 350K Start with cardboard and scissors. Stickyback plastic will follow

I was fairly sure that the repacked megas would still fail the Cadwell noise test so I made up a set of secondary baffles using perforated plate and a cardboard template. Not only did these get me through the Cadwell noise test, I suspect they've also soothed relations with my neighbours. They're slightly restrictive at high revs, but it's a difference you only feel when riding flat out with other Morinis (ie, at the club trackday...) and one that's balanced by quieter cruising on dual carriageways... And by passing the Cadwell noise test with a whole decibel to spare.

Moto Morini 350K Baffle plate in place

(E)Lectrics, (Re)Located

Ever since I fitted the slinky cafe racer seat, the standard steel side-panels have stuck out like a pair of rattly and rusty sore thumbs. Without them, the bike looks slim, svelte and purposeful; with them it looks like a K-series Morini 350 with the wrong seat unit. I've also had a number of ongoing and difficult to trace electrical issues - hey, it's an old Italian bike - that are probably down to poor connections or loose earths, and this was a good chance to chase out those problems because shedding the side-panels meant moving the rats nest / telephone exchange of wiring under the right panel. So it was out with the cardboard templates again. I obviously watched too much Blue Peter as a kid.

Moto Morini 350K Putting you through now, sir...

Moto Morini 350K Paper bends more easily than stainless steel

Once the basic shape was right, a stainless steel version was cut and then beaten into submission... I mean bent into shape. The standard fusebox and rectifier/regulator were bolted in place, and the connections re-plumbed. A few of the connections needed remaking, but a decent set of crimpers from Vehicle Wiring Products and a big box of their bullet and spade connectors made short work of the old red and blue terminals.

Moto Morini 350K Good tools make all the difference

Moto Morini 350K All of these go back in here. Somewhere.
Cafe Racers on Now...

Somewhat surprisingly, everything worked when I'd finished. To celebrate, I went for a 15 mile ride and returned home to find that the horn, brake-light and indicators had become somewhat intermittent. I know indicators are meant to be intermittent ("They're working. No they're not. Yes they are" etc.) but not like this. The main suspect was the fusebox and connection board, where several connections shared a common fuse. A couple of extra fly-leads leads sorted things for the forthcoming MoT, but I suspect the internal connectors will need re-riveting at some point in the near future.

Moto Morini 350K Finished. Golden glint of evening sunshine through rear brake reservoir, etc.

Forks, Fettling

And finally, the forks. The Morini's standard Marzocchis were considered pretty good when the bike was new but in comparison to more sophisticated and compliant modern suspension they're pretty compromised. The damping relies on the correct weight of fork oil (originally the factory recommended ATF - automatic transmission fluid - of an unspecificed viscosity. Modern fork oil is much better, with predictable viscosity if you stick with the same brand) being forced backwards and forwards through roughly and imprecisely drilled holes in the damper rod. Modern forks use a cartridge damper which controls the oil flow more exactly by way of spring loaded valves and shims that allow different rates of oil flow depending on the speed and direction of the movement of the forks. This should in theory allow the damping to be firmly controlling under braking, for instance, but free flowing when dealing with sudden large bumps.

Moto Morini 350K Cartridge emulators

The plan is for Paul "EVGuru" Compton to fit a set of cartridge emulators to modified damping rods, giving a modicum of modern feel to the standard forks. These use the emulator to deal with compression damping and the viscosity of the oil to handle rebound damping. This should give more control, more adjustability, and hopefully a better balance between comfort, handling and roadholding. In an ideal world, we'll even it have it finished in time for this year's Morini Riders Club trackday, in early July.

The first step has been to measure the sag of the bike so that we know what we've changed when it all goes back together. We averaged out the "push down and release" and "lift up and release" measurements to get figures for the front sag with the bike both laden and unladen, and measured the rear sag just for completeness:

Moto Morini 350K Fat bloke on a Morini. Suspension sags accordingly.

  • Front Unladen Sag (averaged): 23mm
  • Front Laden Sag (averaged): 37mm
  • Rear Laden Sag: 35mm

    We also measured the amount of suspension travel being used during brisk road riding by putting a tie-wrap round the front fork stanchion and rear damper rod.

  • Front Travel Used (brisk riding): 130mm
  • Rear Travel Used (brisk riding): 61mm

    These figures suggest that while the front spring rate is close enough for jazz, with 28% of the travel used to support bike and rider, the rear springs are a little soft, using 60% of the travel to hold up my trim and svelte figure.

    Next time: Fitter Forks or Damp Squib?

    Words and Picture: Martin Gelder

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