Clutch on '78 Ciao fails to catch

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Clutch on '78 Ciao fails to catch

Postby mrw8 » Wed Apr 18, 2012 1:31 pm

I own two single speed Vespa Ciao mopeds and my 1974 deluxe starts and runs great. The starter clutch will engage the drive basket and move the piston about half way into a crank of the pedal and it always pops to life.
The 1978 basic Piaggio Ciao is a different story. I have replaced the starter clutch pads and the drive clutch pads and springs. The belt is not too tight. I can turn the drive shaft by hand. And I've take the drive clutch pads off and watched the starter pads expand smoothly when I crank the pedal. They definitely engage the outer clutch basket. But when I assemble it all and crank the pedal most of the time the inner clutch pads will barely turn. The starter pads are either slipping on the inside of the clutch basket or not engaging the sides at all. If I had to guess by the sound I'm hearing I would say that the starter pads are slipping.
Eventually I can get the engine started because it doesn't actually have a hard time popping to life AS LONG AS THE DRIVE SHAFT IS TURNING EVEN HALF A TURN. But as I said most of the time the drive shaft is engaged hardly at all and the outer pulley spins but the inner pads barely move.
The pads and springs are all new and I've adjusted the nut to make sure it wasn't binding the drive pads.
I also notice that if I stall the moped and keep coasting the piston doesn't immediately start turning.
I swapped out the clutch basket from my 1974 and '78 and got the same results. I'm puzzled by this.
I've examined the belt and it's tighter than my 1974 but not so tight that I can't turn the drive shaft with my hands.
I can get the moped started with persistence and it runs very good but I don't understand why the starter pads are not doing their job. Are the new pads flawed or is the basket surface glazed so they can't grip or is a bearing worn out? Electrically there isn't a problem. I can see with my eyes that cranking the pedal doesn't immediately cause the drive shaft to turn and it sounds like they are slipping.
I'm wondering if other Ciao owners have a method of improving the clutch operation. It's a hard question to ask because pedal starting mopeds is never a simple process. You crank the pedal to turn a metal chain that turns the back wheel that turns a rubber drive belt that turns a pulley that turns a set of inner starter clutch pads that then expand and grip the surface of a basket attached to the drive shaft attached to a connecting rod attached to a piston. The piston moves in the cylinder and if you have enough speed to generate spark then the spark will push the piston back and generate more speed and then the drive shaft clutch basket will turn fast enough to cause the outer clutch pads to expand and turn the whole clutch assembly which then turns the pulley which turns the drive belt faster which turns the rear wheel and the pedals and metal chain become obsolete as they are on a coast gear. That's how a Ciao starts at least.

The history of this 1978 Ciao is it's all original. Hardly used but definitely neglected for years. Runs pretty good when I get it started but isn't running like a top yet. It's for sale in St. Louis FIY but I'd like to solve this clutch problem before I sell it.

I have the old starter pads and may swap them out to see if that changes the operation. Is there anything else I'm missing?

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mrw8
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re: Clutch on '78 Ciao fails to catch

Postby mrw8 » Wed Apr 18, 2012 3:20 pm

update:
I double-checked the starter clutch pads and realized they were glazed to a smooth polish. There is plenty of pad left but the glazing must be what causes the slip on starting. I scuffed the pads up with a file and there's a big difference now. I also double checked my inventory of old parts and didn't find any evidence I replaced the starter clutch pads. I found the old main drive pads but these must be the original starter pads. My memory is failing and it's a good reason to keep records of work done.
So, I'll replace the starter pads or discount the moped price $50.
mrw8
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Posts: 28
Joined: Sat Sep 06, 2008 6:49 pm
Location: St. Louis


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