New ring size?

On 31 ago, 15:54, JayC <j... RemoveThis @sysmatrix.net> wrote:
> > Pistons are usually stamped by the manufacturer. STD means standard bore,
> > and then they go up in increments, usually the first is +.005 followed by
> > +.010, +.020 etc... on up to +.040 and sometimes +.050. The box should have
> > this number on it, as well. You need to order rings for the proper oversize
> > piston you have, but some manufacturers simply use one ring size and you
> > have to file the end gaps to a specific size in order to get the proper ring
> > fit. If your box doesn't have the oversize info the only other way to find
> > out is to check via the part number. Sans that, pulling the head is your
> > last recourse.
>
> Thanks - JayC

In metrics, the sizes are .25, .50, .75, 1.00... up to, sometimes
(mostly on Yamahas, afaik), 2.00.

-- Tiago
 >> Stay informed about: New ring size? 

"Tiago Rocha" <diariodastrilhas RemoveThis @gmail.com> wrote in message
> In metrics, the sizes are .25, .50, .75, 1.00... up to, sometimes
> (mostly on Yamahas, afaik), 2.00.

We dun need no stinkin' metrics!
 >> Stay informed about: New ring size? 

> Pistons are usually stamped by the manufacturer. STD means standard bore,
> and then they go up in increments, usually the first is +.005 followed by
> +.010, +.020 etc... on up to +.040 and sometimes +.050. The box should have
> this number on it, as well. You need to order rings for the proper oversize
> piston you have, but some manufacturers simply use one ring size and you
> have to file the end gaps to a specific size in order to get the proper ring
> fit. If your box doesn't have the oversize info the only other way to find
> out is to check via the part number. Sans that, pulling the head is your
> last recourse.

Thanks - JayC
 >> Stay informed about: New ring size? 

On 31 ago, 18:43, "Rider" <no....DeleteThis@nowhere.com> wrote:
> "Tiago Rocha" <diariodastril....DeleteThis@gmail.com> wrote in message
> > In metrics, the sizes are .25, .50, .75, 1.00... up to, sometimes
> > (mostly on Yamahas, afaik), 2.00.
>
> We dun need no stinkin' metrics!

good luck finding english measured parts on a bike other than a harley
davidson!

-- Tiago
 >> Stay informed about: New ring size? 

>On Fri, 31 Aug 2007 17:22:59 -0000, JayC <jwc.RemoveThis@sysmatrix.net> wrote:

>My understanding is that 2-strokes can come with one of two or three
>piston sizes. If I want to get a new ring for my GG125 from the
>Yamaha shop, how do I tell what size I need? I still have the box
>that the currently installed Vertex piston came in; is there is some
>kind of code printed somewhere?
>
>JayC
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Jay,
The Vertex pistons require Vertex rings. Same goes for Wossner
pistons & rings. The Vertex part number for their replacement GasGas
125cc ring is 53010005400, the same as for all their Yamaha 125cc
replacement rings.
http://www.vertexpistons.com/Vertex%20catalogo%202006%20web.pdf

While you can buy a Wiseco piston kit that will fit both your GasGas
and a 2001 Yamaha 125, it only comes in one "125cc" size, unlike the
oversized (by .01mm per size) piston kits for the larger bore GasGas
bikes.
These "marginally larger" oversized piston kits for the larger bores
all use the same rings.

Vertex makes these marginally larger piston kits for both Yamaha & GG.
They all take the same ring.

The Wiseco oversized piston kits for the yamaha 125 will require
boring and re-coating (cheapest way to go if you choose to overbore)
of the cylinder (or a sleeve job).
(I just looked this up to make sure.)

(disclaimer: there may be more options that have opened up for the
125cc GG bikes in the last year, but at the time I was a dealer,this
was it.)

Any aftermarket distributor for Vertex pistons should be able to get
your Vertex rings ( if you can decipher the numbers on the box) for
the 125. It was a Yamaha Vertex piston kit box, wasn't it?
Show it to the dealer/parts guy. If he doesn't know how to read the
label, get him to call "tech help" from his distributor. If he's too
lazy to call tech help for you, get another dealer to help you..

Good wrenching to you.

Wudsracer/Jim Cook
Smackover Racing
'06 Gas Gas DE300
'82 Husqvarna XC250
Team LAGNAF
 >> Stay informed about: New ring size? 

> The Vertex pistons require Vertex rings. Same goes for Wossner
> pistons & rings. The Vertex part number for their replacement GasGas
> 125cc ring is 53010005400, the same as for all their Yamaha 125cc
> replacement rings.

Great. A choice of 1, which makes it easy - just the way I like it.

> Vertex makes these marginally larger piston kits for both Yamaha & GG.
> They all take the same ring.
> Any aftermarket distributor for Vertex pistons should be able to get
> your Vertex rings ( if you can decipher the numbers on the box) for
> the 125. It was a Yamaha Vertex piston kit box, wasn't it?

It is a Vertex YZ125 piston. Based on what the previous owners told
me, it should still be fine. I thought that I might've needed rings
based on the bike's anemic performance. I was going to do a
compression test this past weekend (didn't get to it - 3 days of
partying got in the way...we really celebrate school starting , and
was just trolling for info before I had to go out a buy stuff. After
making the couple of jetting changes I'm beginning to think I don't
need to crack the motor after all. However, if it's lacking
compression, I might as well change out the whole top end, and I'm
currently assuming I can use the whole YZ125 kit (includes gaskets/
seals), which is ~$120.

What's a good compression number for a 125? I'm thinking anything
around 150.

> Good wrenching to you.

Oh, I hope not...

Thanks - JayC
 >> Stay informed about: New ring size? 

**************************************************
>On Wed, 05 Sep 2007 15:51:48 -0000, JayC <jwc DeleteThis @sysmatrix.net> wrote:

> However, if it's lacking
>compression, I might as well change out the whole top end, and I'm
>currently assuming I can use the whole YZ125 kit (includes gaskets/
>seals), which is ~$120.
>
>What's a good compression number for a 125? I'm thinking anything
>around 150.
>
>> Good wrenching to you.
>
>Oh, I hope not...
>
>Thanks - JayC
**************************************************
You can use the whole 125 Yamaha piston kit, but I'd be very surprised
if the seal and gasket set would work for you. You can probably find
this out at the Yamaha dealer, if you know what you need.

(Before the parts prices went up about the time I closed the shop) I
used to sell a complete engine gasket set (not including seals) for
right at $80. I think I still have at least one complete 125cc set
around here, and have a bunch of the 125cc gaskets for sale
individually.
A "hand assembled" GG top end gasket set was costing about $34.
(base gasket, head o-rings, exhaust manifold gasket, pv cover gaskets,
thermostat housing gasket)

I think compression should be higher than 150, but don't know for
sure. Most of the 200, 250, & 300cc GG engines run around 190+ psi.





Wudsracer/Jim Cook
Smackover Racing
'06 Gas Gas DE300
'82 Husqvarna XC250
Team LAGNAF
 >> Stay informed about: New ring size?