Modern Vespa

hi chaps,
iam rebuilding my mp3 500
iam trying to find either a piston and rings for a mp3 500 2013,
i have noticed on mine that the top ring is stepped
are all the mp3 500cc top rings stepped on the 92mm bore and the 94 mm bore ?

thanks

Well, at least mine (for my 2003 Big Beo 500, 92mm bore) is L-shaped. So I guess they all are.

the cracked pistons are few there are more with broken piston rings the problem of loosing oil is or the Piston or the Piston rings

Last edited by rodymanners on Sat Sep 18, 2021 12:52 pm; edited 1 time in total

just buy a new set piston rings and barel from the HPE

got them in stock

thanks guys i got all my parts sorted now, mine is actually a 94mm ( and yes it is L shape top ring and ring land, cheers

Hi who are hpe ?? UK or?

HPE is the current iteration of engines produced by Piaggio.

If memory serves me right, HPE = High Performance Engine

Predecessor was the IE.

Basically the same motor, but the HPE was tweaked to meet current Euro emissions requirements and produced a couple of extra ponies as a bonus. Nothing earth shattering, it is pretty much the same since 2006.

so what does maskor mean get a new piston and rings from HPE ?

He means that you may buy new parts with addressed issues of cracked piston land.

I think he meant "for" the HPE. And Maksor has them in stock, so I think that any dealer should be able to get a cylinder/piston/rings set. If your cylinder is OK, then make sure you get the right piston- there are four sizes of standard piston that are closely fit to 4 sizes of cylinder, at least on the older (2009) 492cc MASTER engine. Mine had a "C" stamped on the top of the piston, indicating the third size up. You won't be able to bore the cylinder since it's just coated aluminum, but a *very* light honing with a ball hone will help the rings seat faster.

If you had a piston land crack, then it's likely that you had suffered from detonation in the past- early pistons were very prone to detonation damage- cracks between the top and middle rings. So when you put everything together again, use an extra mm of bottom gasket to lower the compression a bit, and always use the highest octane fuel you can find to minimize detonation.

Last edited by Squeazel on Tue Sep 21, 2021 11:54 am; edited 2 times in total

The cracked damaged and cracking developing mainly on the 1st ring land lip was down to the 500,/400 master engine was the piston casting being very thin in that area on the inside once the land had been turned ,
so the heat would cause the weakness in the structure of the land lip , and either crack or let go, inside , then they beefed up the piston casting .