Pistons

[Peterp]

Hello all, I’m struggling with selecting a piston for my TV175 3. At present it’s 63.2mm, so next step is 64mm ????
I’m understanding your remark Paul about “good luck with that”.
Should I go for a two ring piston or three ring? Indian, Chinese, Korean, Taiwanese or Rimini.
Beginning to think I should have bought a Vespa

[hullygully]

64mm is a large step up, by-passing 3 other oversize bores.
your best bet is to first find an oversize piston & rebore to suit bud
are you sure the barrel is a tv175, the same with the crank.
If its just a sx/li crank with a bored out 150 barrel then the world's your oyster

[Peterp]

Hello Hully,
Yep, it’s 175, with a 63.2mm piston. But,,, I really don’t know enough about this to make a decision, by that I mean, confusion creeps in as to which pistons are quality. My days of mechanicing was four stroke from 900cc up to diesel 14000cc.

[Martin s]

Hi,
Rimini lambretta have a 63.6 three ring original Borgo piston, its 120 Euro though, plus postage.
Depends how original you want it. You can get a Suzuki copy piston from Taiwan at 64mm cheap, but I think
they are still reasonable quality.

[hullygully]

I'd go with the two thin ringed jap piston every time Pete

[Peterp]

Thanks Hully,
Where would you go to for this,

[Storkfoot]

Pete, read this again. It’s not complicated but it isn’t a straight swap for an original TV175 piston.

I’d recommend speaking with Martin at Chiselspeed if you go down this route.

Paul

viewtopic.php?f=10&t=16449

[Knowledge]

Hello Hully,
Yep, it’s 175, with a 63.2mm piston.

Peter, are you sure you know what you need. I am not sure you do (yet).

There are two types of Lambretta 175cc. Those that were manufactured by Innocenti were known as the TV175. They differed from the Li150 as they used a bigger 62mm piston and crank with a longer connecting rod (but still 58mm stroke). To accommodate this, the 62mm piston had the gudgeon pin closer to the crown, making it unique within the Innocenti range. It was available in progressive 0.2mm oversizes.

Meanwhile, pattern parts manufacturers saw an opportunity to offer 62mm pistons as a direct replacements for the existing Li150 pistons allowing the capacity to be increased by 25cc once the 150cc barrel had been bored from 57mm to 62mm. However, these “Li175” pistons are different to the TV175. They are not interchangeable.

So Peter, do you have a TV175, or an Li150 bored out to 62mm (well, 63.2mm)?