Modern Vespa

I know you all like to look at dirty pictures so here's one of my piston.

I was riding up to Long Beach last weekend for the LBCSC monthly ride. Took the 5 freeway for about 20 miles through Camp Pendleton (it's either freeway or take a 2 hour diversion to get around the camp), going steady 3/4 to full throttle - varying it. No problems. Pulled off at San Clemente and stopped to make a few phone calls. No problem. Carried on riding on PCH, stop and go traffic getting up to 45-50 ish. No problem.

Decide I'm getting thirsty after about 15 miles so in Newport Beach I stop and have a drink. Go to start up again ang the engine turns over and I here a metalic pink-pink-clink-clink sound and it dies. Problem.

This is what I found when I opened up the cases yesterday. The area around the wrist pin that the circlip clips into had disintegrated and the clutch side circlip had done the same thing.

WOW!

I can't even begin to think how that could happen.

Mark that sucks.

How do you get a hole in your piston?

Looks like you are ready to kit that thing

I will be at Hensley's Flying Elephant Bar tonight. If ya need a drink let me know.

J

I'll be putting my old jug and piston back on on Monday, so at least it'll be running. Thinking about a kit, just need to decide which one.

I'm going to see Deadbolt down in SD tonight, but have fun at Hensley's

Wow that sucks... good luck getting back on the road.

Would be instructive to know what piston this was... Looks like a wire circlip so it wasn't original... was this a pattern stock kit?

Yeah, it was a stock replacement kit that I got from MotorSport back in May. I had about 2000 miles on it.

oofah... that sucks the big one.

i'm with HP, this looks to be some type of mfg'ing failure. while i've seen my fair share of busted parts, this intrigues me.

i looks as if that's been going on for a lonnnng time and it finally just shit the bed.

interested to know what the orgins of that top end were.

best,
-greasy

Engrave it "offering to the god of speed" and place it on your bookshelf.

Never seen damage like that before

i'm glad it did'nt happen on the pendelton/onofre stretch





although you would've been closer to home

thats suck but glad u have a replacement piston, still how can ur piston gave up like that unless u drive it like hell (speechless)

I saw this on a Vespa in Italy...

agreed. that is a massive failure. you should keep that forever.

my last offering to the speed gods went like this:

Looks like preignition to me , poor gas and bad ign timing wrong spark plug heat range <<< no matter what it was it's broke
EDM

That really sucks. What does the bore look like?

Factory timing marks lined up and checked with a timing gun and degree wheel.

B8ES plug and always 91 gas

But if you can explain how it would do this to the area around the wrist pin only I'd happily accept that and learn from it.

Bore looks good everywhere apart from where bits of the circlip (?) got caught between the the barrel and piston - there's a big gouge that I need to look at more - it's pretty deep and may not be worth re-boring.

i will say it was a bad cast on that piston

either air or dirt got in the pour and you gave it a bad day

I've heard of the wrist pin retaining clips popping out either because of improper installation or manufacturing defects. Once out, they rattle around as your piston slams up and down. It looks more like this scenario to me.