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)?

[Peterp]

Thank you again, and thanks Paul.
This is in reply to knowledge, it’s a genuine TV175 series 3, obviously bored out to 63.2mm.
Paul, if I could find a 63,2mm piston I would just go that way, my local engineering mate says there is only a thou in it.
I’ve found them but from India, this is where I’m unsure as to the quality, and, for what I want will it suffice.
The next option is to go 64mm, but, as I’ve already mentioned, which manufacturer, two rings three rings etc.

[shane BBoys]

Thank you again, and thanks Paul.
This is in reply to knowledge, it’s a genuine TV175 series 3, obviously bored out to 63.2mm.
Paul, if I could find a 63,2mm piston I would just go that way, my local engineering mate says there is only a thou in it.
I’ve found them but from India, this is where I’m unsure as to the quality, and, for what I want will it suffice.
The next option is to go 64mm, but, as I’ve already mentioned, which manufacturer, two rings three rings etc.

https://scooterrestorations.com/product ... ston-rings

Try scooter restorations they have different sizes of TV 175 pistons.
Cheers Shane.

[Storkfoot]

The Diamond piston that Shane highlights looks a decent plan.

It’s only £30. Get a proper local motorbike shop to check you have a piston to bore clearance of 0.1mm and run it in for a few hundred miles, and it’ll probably be fine. Oh, and as knowledge mentioned, don’t fit a head gasket as the squish is big anyway. Without a head gasket, you need to make sure the cylinder and cylinder head mate well.i do this by putting some wt and dry paper on a flat surface, such as glass, spraying WD40 on the wet and dry, and moving the surfaces around until I can be fairly sure they are precisely flat.

When I put the top end together, I use a loctite sealant. I think it’s 270 but I need to check that. I’m pretty sure that’s the piston I have in my standard TV

[Peterp]

Just a random reply Paul, met up with a friend of yours today, Alan Lovell, I think it was Lovell, from Sealand Road Chester. He told me lots about you, but I promise to keep it to myself

[Storkfoot]

Just a random reply Paul, met up with a friend of yours today, Alan Lovell, I think it was Lovell, from Sealand Road Chester. He told me lots about you, but I promise to keep it to myself

I think you’ll find that isn’t me. Paul is a common name

[Toddy]

Just a random reply Paul, met up with a friend of yours today, Alan Lovell, I think it was Lovell, from Sealand Road Chester. He told me lots about you, but I promise to keep it to myself

I think you’ll find that isn’t me. Paul is a common name

It is

[Rich Oswald]

Just a random reply Paul, met up with a friend of yours today, Alan Lovell, I think it was Lovell, from Sealand Road Chester. He told me lots about you, but I promise to keep it to myself

I think you’ll find that isn’t me. Paul is a common name

[Peterp]

Just an update, got a GOL 63.4mm piston from John Milverton via Jason at Saxon Scooters.
Progress resumes.

[Peterp]

Meant to ask, if I did want to reduce the squish, only if… which way would you suggest, head or barrel

[Knowledge]

Head.

I have tools to do such work.