P501- ROTTURA ALBERO SUPPORTO RUTTORE

[kjjohnson]

A pdf file on my website for clutch overhaul - go through it. Explanations on most photos. Ken - https://www.kjjohnson.ca/piaggio/Piaggi ... erhaul.pdf -

[eliap501]

Dear Ken,
hopefully we managed to find a professional mechanic to take care of my p501.
Since he will make a full check-up i was thinking that maybe i could upgrade the power a bit with a Polini 220 cc pack.
My ape is a P 501 from 1989 (second generation) do you know if the piston pin diameter is 16 or 18?
Is this the right piece i should buy for my ape?

https://catalogue.polini.com/it/product ... r=products

Thanks a lot,
Elia

[kjjohnson]

A Polini kit will increase displacement and horsepower but you will have to upgrade the carburetor for more fuel flow or you'll burn out the piston. The original cylinder can be bored four times to use oversize piston kits. 16mm wrist pin original. My advice is upgrade what you have as it can be done several times and is cost efficient. See photo as it shows a Polini piston after installation when fuel flow wasn't changed in the carburetor to adjust to the increased displacement - Ken

[eliap501]

Dear Ken,
I brought my p501 to an official Piaggio Mechanical workshop.
They doubled checked all the clutch components and confirmed there is nothing wrong with that including the gear behind the clutch.

They said the problem was the pressure plate (see pic. attached).
So i found a replacement wich they installed it with a brand new pin (the tip of the previous one was broken again).

I've now been bought several bronze rings (worn out) and many pins.

Do you have any other ideas about why my ape is doing this?
I'm starting to give up hope.

Thanks a lot for all you help!
Elia

[eliap501]

i forgot to say that the pin broke up again after less than 3 days,
So I'm at the starting point once again.

[kjjohnson]

I'm starting to think there's not enough room between the clutch and the clutch cover. I've never seen wear like that in 24 years working on Api. It makes me wonder if you have the correct clutch for that motor. It's like you have a machine shop and when it spins it's chewing things up because there's no room. Wish I was closer, I'd pull it apart myself. How close are you to Prato? - Ken

[eliap501]

Dear Ken,

thank you for your answer it seems strange that they didn't notice it at Piaggio (they said they disassembled all the components of the friction)
I will s
I live in Verona so i'm like 225 km away from Prato, I don't really think that my ape will manage to do the trip (at least for now)

So the Piaggio workshop, basically said that the problem stands in the material of the "piattello di spinta" (notice that i bought a brand new one, and it happened) which is steel that when goes against the "nottolino" which is made out of bronze causes the wearing of the bronze and the sequent breaking of the pin.

So they made a modification to my original piece adding some bronze in the place where it has to push the other bronze piece and giving it the perfect shape with a lathe.
They said that this will solve all the problems of my ape but still doesn't make any sense to me, but i'm not an expert so I can't do anything different from waiting them to do it.
I'll let you know,

Thanks a lot,
Elia

[kjjohnson]

If all the pieces are correct for that motor and properly installed there's no need to modify anything. To create that much wear means the parts are binding and tiny shavings are causing seizure so the tip breaks off the drive pin for the distributor.

In this motor I'd overhauled the brass actuating pad was very worn and also the steel thrusting plate and someone installed a washer on the drive pin as I suppose spares weren't available in Quebec where it was located. I've come across this twice in my time.

So much pressure caused heavy wear on the spacer washer behind the drive gear and also wore the lip on the rear of the drive gear. A common mistake is not leaving space between thrusting plate and actuating pad by tightening the clutch cable too much therefore not leaving a space between them for oil to lubricate them. - Ken

[eliap501]

Dear Ken,
I spoke with a friend at Vespa Club last night here in Verona.
He thinks that the problem might be the fact that the crankshaft is crooked.
According to him, the shaft is not working straight but is doing an eccentric rotation.
Please see the burnt lines in the middle of the shaft in the picture.

What do you think about it?

[kjjohnson]

Do a test. Insert a new drive pin in the end of the crankshaft. Install the worn thrusting plate and spring. Rotate the engine and fix a pair of calipers in position and opened slightly larger than the pin shaft so you can observe if it rotates with or without wobbling. It may be as simple as the area in the end of the crankshaft that holds the pin is not allowing a good fit because of wear.
If it were here I'd pull the motor, mount it on my test stand and start going over it from there. Bearing wear on the end of the crankshaft would cause it to wobble if that's potentially the problem.