Does anyone know what the letter (a,b,c) and the number (1,2,3) mean ?

According to the handbook number is diameter, but doesn't say what the letter is.

I'm trying to replace a piston with broken ringland and have 7 spare pistons with either same letter or same number but not both.

Don't care about those markings...

measure your bore and measure your pistons's diameter, and then use the one according to the oil clearance required in the 3SGTE handbook.

_________________
Wolf_Tm
TM 250 enduro 2 stroke
GT-four ST205 Snowy White with selfmade 3SGTE v4.1 - [2.34kg/bhp DynoDynamics]
http://www.youtube.com/WolfTm250
http://www.facebook.com/wolf.tm

I'm not trying to build an engine to last another 100K miles, just bodge one back together to last a few months while I'm building up a forged engine.

_________________
If at first you don't suck seed, try drier grain.

It is the same.
I ALWAYS check with gauge Piston to Wall tolerance and bearings oil tolerance, even if the engine have to do 1 km.
Time to check these things is less than the time you spent to write on this forum this thread.

_________________
Wolf_Tm
TM 250 enduro 2 stroke
GT-four ST205 Snowy White with selfmade 3SGTE v4.1 - [2.34kg/bhp DynoDynamics]
http://www.youtube.com/WolfTm250
http://www.facebook.com/wolf.tm

Hi Chris,

The numbers are definately size but i think the letters are too

If I remember right the letters are major (rebore?) sizes and the letters are fine (tolerance) sizes. So you might find a combination of 1a, 1b etc in an engine that's not been worked on

I need to consult the bible to be sute though......

I had a PM from someone who noticed the letters seem to be paired with conrods. I'm wondering if it's small end diameter.

_________________
If at first you don't suck seed, try drier grain.