TMaxx 2.5 won't stay on

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luis12285

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I can not get the darn thing to stay on. It is about a week old. I did the standard Traxxas break in. Today I pulled the engine out and completely cleaned it. I did notice the piston was highly discolored. I cleaned it with some toothpaste. And it looks a lot better now. My issue now is i will not stay on if i let go of the throttle. All needles are factory set. For it to turn on I have to have a quarter pull on the throttle. To get it to idle even a little bit the idle screw has to be all the way in. Anyone around here know what steps I could take to get it running again? Also from break in it has always ran hot. Even while it was rich(spitting fuel out of the pipe) it was still hot.
 
Give us a temperature you say is hot?...toothpaste? Really..I wish you would have asked some questions before this, toothpaste is verry abrasive, I hope you got every last bit of it cleaned out of the engine.

Factory settings are just a starting point! Sounds like she is way rich on the lsn, also what glow plug are you using? A plug usually gets beat from the break in process, I suggest an os lc4 plug brand new!
 
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Brand new traxxas super duty spark plug. Did not have a temp gun but a splash of water sizzles away instantly. I've read a few places that toothpaste is good at cleaning off the piston head

---------- Post added at 2:29 AM ---------- Previous post was at 2:28 AM ----------

The original glow plug died a tank after break in
 
Spitting raw fuel and running hot isn't right. We need an actual temperature. Hot to the touch is NOT hot for prime running. As stated in the above post, factory settings are only for the break in and you should have started tuning for performance.
 
I did tune for performance. It was running awesome. According to the traxxas manual after about 10 tanks it's time to break it down and give it a good cleaning. I did that and now I can not keep it turned on
 
I've never heard traxxas say to rip apart a new engine at 10 tanks for cleaning, in fact this is the first time I've ever heard that!

You probably didn't tighten the cooling head properly and are experiencing an air leak there, not to mention the toothpaste residue on your sleeve
 
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I made sure the toothpaste was gone... Electric engine cleaner+WD40

---------- Post added at 3:14 AM ---------- Previous post was at 3:13 AM ----------

I'll try it again tomorrow after work and see if I can get it tuned properly
 
Take the cooling head back off and make sure the copper washer/gasket is still there,make sure all surfaces are squeky clean "just with a clean rag no fancy cleaning procedures ie toothpaste or whatever else"place the head on and tighten like you would a set of lug nuts just a little at a time to ensure an even tightening
 
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"The piston skirt has a notch cut out that should be towards the exhaust.....I have put one in backwards before lol."

I think you're about to do it again there Bud!!! The notch in the piston skirt goes in facing the carburetor end of the motor, away from the exhaust. It is cut in the skirt to uncover the intake port sooner on the charge stroke. I know this because I installed one backwards about 2 months ago. And more than likely, the next time I rebuild one, I'll have to look it up again just to make sure. :)
 
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OK being I don't have one with me mrbones could be right...It's been a while since I have done one. I do know for sure that you have to face the oiler hole in the connecting rod toward the crankshaft, as long as you didn't remove the piston from the rod this will ensure it's installed correctly.
 
Both the cutout in the piston skirt and oil hole in the rod should be toward the carb side of the engine.
 
I did install it backwards. I figured the notch had something to do with the sound waves resonating back to the engine. It's a bit deceiving. The notch is about the same width as the exhaust port. The exploded view on Traxxas did not show the other side of the piston head. When I get home tonight I will give that a try. I did do a leak test over the whole system including the fuel tank yesterday and nothing was an issue except the front bearing. From what I read the front bearing is not designed to be air tight and a bit of air is exceptible

---------- Post added at 10:47 AM ---------- Previous post was at 10:47 AM ----------

*Acceptable
 
That was the exact issue... I runs like a champ now. So good that I bent 2 of the front shock shafts bashing it today
 
Well I'm glad you got it sorted out and are having fun with it, the traxxas big bore shocks for 60$ on ebay are a good upgrade
 
When you explained the situation bad memories came rushing back from making that same mistake.....just glad mrbones pointed out my bad info and Snook Man confirmed it! Once you get those shock shafts fixed post up a vid of that beast!
 
SMaxxin said:
When you explained the situation bad memories came rushing back from making that same mistake.....just glad mrbones pointed out my bad info and Snook Man confirmed it! Once you get those shock shafts fixed post up a vid of that beast!
Click to expand...
You're the one who figured out he might have the piston in there backwards. That's a pretty outstanding observation. I think it's a wonderful thing that someone can post a problem and everyone gets together and resolves it.
 
luis12285 said:
That was the exact issue... I runs like a champ now. So good that I bent 2 of the front shock shafts bashing it today
Click to expand...

Gotta love those crappy weak Traxxas shocks!:hehe: Those Traxxas BB hotrod recommended really are a great shock.
 

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