Scooterotica

I thought my scoot was down on compression.

A ring gap of 3mm probably had something to do with it! (that's three whole mm, not point 3)

I don't actually know what make of piston I have but its 71.00mm (helpfully stamped on top) and the rings are 1mm thick.

Where's the best place to get some?


Would these fit?

http://www.lambrettaspares.com/spares/r ... g7100.html

Firstly where are the ring pegs located in your piston,central or to the top of the groove ? Is the piston a motorcycle one or a Lambretta one ? If you are not sure post a pic.

The pegs are central in the groove. There are two ring grooves and a shallow bottom groove presumably to aid lubrication

Now I'm out of the garage and the hypothermia is wearing off I've noticed the letters "MBD" stamped underneath the piston crown. I guess that means that it's a race-tour.

Yes it's a Racetour so they will be the rings needed you found But I would check the piston/bore clearance as if excessive that would put all the thrust onto the rings contributing to heavy wear unless your motor is very high mileage. 3 mm is a massive gap ,normal rings would have snagged yonks ago but Racetour rings can be bent without snapping.

Cheers for that.

Hopefully the ring gap will be slightly smaller than 3mm. No wonder i could turn the flywheel with one finger. The bike still ran like a charm though!

wack 63 wrote: I would check the piston/bore clearance as if excessive that would put all the thrust onto the rings contributing to heavy wear unless your motor is very high mileage.

What clearance is acceptable? The motor is high mileage but not ridiculously so.

Piston Rings arrived today. A ring gap that I can barely see is a bit better than 3mm!