Here is a pic of my 3.3. The motor has only burned up about 2 1/2 gallons of fuel since i got the truck about a month ago or so. This is the first time that i took the cooling head off the motor. I noticed this really dark black color on the piston. If i had to guess, that probably isn't good. To lean, right? Well if i keep running the motor alot richer, will that black color go away, or is that there forever? And will they affect the performance of my motor. Dont be afraid to lay it on me, i need to know what to do with this mess. thanks

Looks nice and rich too me! Atleast its not pitted and clean (Thats bad!)


I think its fine as long as your running around 200+ degrees

Considering the look of the piston, and the fact that the engine MELTED the heat shield (The yellow sleeve over the fuel line), I would say that you were running WAY too lean. IF the engine still runs, you should richen it up quite a bit. Also, I would recommend investing in a temp gun. A cheap one will run you about $25, a LOT cheaper than a new $100+ engine, which will probably not last too long running as lean as this one was.

There are a few threads on here with great tuning tips. Take the time to read through them, and take it slow with tuning your engine next time around. Watch for a nice steady trail of smoke coming from the exhaust, and keep the temps in the 240-260 range on the Traxxas engines. (Some will still run great a little hotter, but until you are more comfortable with tuning, that is a good heat range to stay in).

Hopefully I don't come off as an @$$ in this thread, but you did say "Dont be afraid to lay it on me,"

Good luck.

Rocco, that heat shield won't melt like that, even running in the 260-270 range. It looks like he was running a LOT hotter than that.

If it was lean wouldnt the pistion be clean???

Thats black thing looks worn through not burned...

In another thread it said that he melted through the black and yellow pieces of heat shielding.......

black is from fuel, lean would leave the piston pitted and look like it was sandblasted, that looks fine to me

well, i have a temp guage. But its an onboard temp made from traxxas. And that heat shield came off my pressure hose. It was laying on the header and fried it all up. So the motor isn't getting hot enough to burn through that. I would be really scared if that was to happen. My temp are usually really high. But i think the temp guage is way off. It usually read like 320-360, but when i go to lean it some more, it keep gaining in power. I am pretty sure i am far from the best performance, but the temps are Reading crazy. And now that this huge black spot on my piston has arrived. I'm not sure what to do... I have two threads up, one on here and one on traxxa's web site. And one person form both said it looks to lean, then the other two say it looks to rich. Not sure what to think yet.

It is a little blurry, so I may be wrong, but it looks melted to me. I never had a problem with it wearing through on my maxx, and running at 270, I never seen one melt. The heat sheild really doesn't move much, so I can't see it wearing a hole in it, especially in only 2.5 gallons.

Maxx-Breaker, is the heat sheild worn through, or melted?

ok take a pic of ur plug for us

ok one second

I think it looks almost too rich... Id buy a desent temp gun and throw that onboard out the window...
I bet your barely in the 200's... I bet the onboard is reading the exsaust port which is always hotter , cuz it doesnt have a cooling head bolted to it

Temp guage, even a little off, should not be 100 degrees off. Why have one if you ignore it anyway?? Make sure you have smoke at idle and full throttle, good pop and no stuttering off of the line, and no bogging at the high end....

This is WAY too hot.

If Mike and Rocco say that the coloration is normal, check the placement of the temp sensor. It should be in the gap by the lowest fin, pulled all the way in, with the heat sensor near the back of the engine. If the Temp sensor is in the right position, you may have an airleak causing the engine to run that hot.

i remember indoor when rocco's stuff wasnt running great his lsp, and i helped him tune it, he came off and somebody temped it with a POS temp gun and it said 240, and an exergen said 260 or 280 so ya it could be like 100* off