This thread couldn't have come at a better time. I found this thread by chance via a random google search. I have a
Xtech EB Mods Pro engine and pipe in my truggy. It was running absurdly crazy fast when the temps decided to drop. My tune was lost and i became confused. I asked the guys at my track why my engine sounded funny coming off the straight... Basically i would let off the throttle amd it seemed like there were three levels to my low end tune. It would drop a pitch until the engine would sputter and die. So i searched all over the net trying to figure out and learn what was going on. I found my answer on youtube via a horizon hobby engine tuning video. Turns out my engine finally broke in at 2 gallons and when it did this my lsn became super rich. So far i have turnes my lsn 3 full turns back (one turn mean a full 360 degree rotation of the needle). My engine now idles well again and can make my truggy wheelie. Temps are a nice 220 at empty tank, and the top end sounds like i have room to grow. Sadly my air filrter came off so i shut down my engine amd took her apart. I found tons of black carbon at the top of the piston. So i did a search of what this meant and thats how i found this thread... Awsome!!!!

So whats the purpose of removing the extra head shim after break in??