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Apologies if this has been covered before/somewhere else, but my Dart Owner's Manual describes lots of technical procedures on the motor, but omits mention of the carbs or carb balancing. My Morini W/shop manual mentions plugged take-offs on the inlet elbows for connection of vacuum gauges on the 350 non-Darts, but mine are solid. Apparently the 500s have alternative connections, and I wonder if they relate to the spouts on the carb bodies of my 350 Dart that appear to pull vapour from the breather box. Is this where I go? I have a suspicion that a Scottoiler was connected at the T-piece on this harness....

Thanks,

Nick (getting there!)

Hi Nick, i balanced my 400 yesterday.
My inlet elbows are solid too
I used the little tube who's connecting the 2 carbs.

Later Morinis of all models had balance pipes and the vacuum ports on the inlet rubbers weren't drilled. Replacement inlet rubbers all have to be drilled to add vacuum ports.

The balance pipe makes the bike less sensitive to carb synchronisation, but makes it more difficult to balance the idle stops because the speed rises when the pipe is reconnected.

On bikes with a twin pull throttle I prefer to remove and blank off the balance pipe. The Dart has that horrible cable splitter with lots of loose joints and I could never get a Dart to synch up (and stay there) as well as I'd like. I found the splitter from a Freccia (throttle + oil pump) was better made with thicker plastic, but being otherwise identical. I think some people have used aftermarket splitters.

As stock there's a T piece in the balance pipe that leads off to a sprung loaded valve plumbed into the breather assembly. The valve can stick open (one cause of the revs 'hanging') and the bike runs better without it. It improves fuel economy without it too!

Thanks for those comments, chaps! I suspected that some of the pipework on Darts was more about emissions compliance than performance...

I got the fuel system primed yesterday, anticipating subsequent vee-twin music, but a quick check showed fuel gushing out of one carb's overflow, so there's a problem with a float valve. Hopefully, I didn't leave an O-ring out!

As to sloppy throttles; I dissed the original one-into-two cable splitter on my Cagiva Alazzurra and made up two cables without adjustors to run directly into the twin-pull twist-grip (one had been blanked off). Making the cables from stainless inners to an exact length requiring only the adjustors on the carb tops gave a silky-smooth action and was the best move ever in getting carb-synching to last.

Nick