I recently bought a os 21rg-x(p) for my mad force and when i look down in the glowplug hole i noticed that there where a lot of small brown black dots on the piston is this normal???
This may be a stupid question but i just want to know[&:]

Please if someone can answer to this question do it i must have an answer[8D]

that is not normal that means you are too lean that baked on stuff is carbon deposits from caster oil What this means is that your motor had a lot of residual fuel sitting on the piston when the motor was still hot.
Use a toothbrush and dishsoap (the cream one).
If you can clean the black deposit on top of piston troughly (without using metal polish)... then the engine is still in health condition. Just wrong setting, use colder plug and or better fuel.
The (not-perfectly) burnt fuel/oil is creating that deposit.

If.. the carbon still there and the top surface of the piston is like being hammering by thousand needle.. creating a rough surface, then you have a problem.
That is early stage of pre-detonation, your combustion chamber is exploding far before TDC .Could be the plug is to hot / too lean setting . If you keep this setting, result is obvious.. broken con rod or broken crankshaft.

but the engine is totally new never fired up??? strange

then that odd go were you bought it and then ask them, If they say its normal then also ask them to show you another

It's just how the piston looks after it has been made. All of my engines had the little black dots on top of the piston and it didn't bother anything performance wiese. They'll wear away after you break in the engine and then run it for a gallon; just the way it is.

Ok thanks for the answer Aerobirdbrain i got a bit worried when rodrigo said that it wasnt normal and that my engine maybe were busted.

Now i just hope that i can get it started to its been a bit troublesome and it didnt start last time so i havent broken it in yet. Maybe i just have to lean the high speed needle down a bit.

I didnt know that it was a totally new engine normally you see little black/brown dots when you run the engine too lean, but now re reading your post I think you are refering to the very very little dots that come from fabric so sorry If I scared you.

Yea i got a bit scared, buying a new engine and then read that it may be broken already when i bought it

But we will see if it starts soon.How much can you lean it?? because its at 3 turns from fully closed and thats a bit rich can i lean it as much as 1/2 turn when i break it in or do i have to have the needle at 3 turns.

if u gona lean it as much as u want 2. u gota keep an eye on the temp,
use a temp gage of some kind. always keep it bout 15 or 20 degree below book limit if u use a temp gun point it at the plug.

Ahhhhhh[:@] when i get the engine started and i try to push the throttle gently it just cuts out what can i do. Yea BTW Im going to buy a new glowplug it seems like its shutting of a short while after i take the glow ignitor of. and i have only decreased the high speed about 1/4 not more.

is the engine up to temp? if not warm it up first witha hair dryer or heat gun. it will make starting alot easier. and it shouldnt cut out when you give it throttle, but if it still does then lean out the low speed a tiny bit