traxxas vs other brands!!

[shoshe]

I have a tmaxx 2.5r (brand new motor w/ 5 tanks through it after correct break in) and a nitro 4tec 2.5r (old motor not sure how old though) and my buddy has a brand new tmaxx 3.3. We are both running Backyard Basher 20% fuel and all 3 machines cut out at full throttle. I have adjusted and adjusted. Should I swap to the traxxas fuel? Could this be the problem? Do I have to use the same fuel I've used to break it in?

 

[SMaxxin]

It sounds like they are lean on the HSN or they all have air leaks. Fuel can play a big roll in tuning but I have never had it make that big of a difference.

 

[Timmahh]

check the carby areas. TRX motors are Notorious for bad carbs.

if you can find an OS 11* carb, it should fit and solve some possilbe TRX carb issues.

not heard of BB Fuel or used so i can't comment.

 

[shoshe]

air leaks could be a problem as I have not checked that. I can tell you that my 2.5r has no zip ties on any of the fuel lines, but the 4tec and the 3.3 both are tied. I have checked with my local hobby shop and he says that traxxas has approved all the fuel he sells. I have reset to factory settings and replaced glow plugs. I did learn that I was not setting the low speed needle correctly, but that being fixed still does not alleviate the stalling problem. 2 of the motors are new so I can rule out the junk carb (or so I assume and we all know where that leads).
Might this turn out to be a clutch problem? What about the one-way bearing? Will that cause stalls at WOT?

 

[Rolex]

I always ran my .15 Tmaxx on Blue Thunder. Never had a problem. Broke in and ran my 2.5 on it also. I did a lot of tuning at my local track and started to wonder why other 2.5s I tuned started to out run mine. Fuel. I tried their Traxxas Top Fuel, and after tweaking it for a few tanks, I was up and running with them. I gave away my Blue Thunder and bought a gallon of Top Fuel. All I can say, from seeing it first hand, is Traxxas engines love Traxxas fuel.

 

[SMaxxin]

Don't count out the carb just because it's fairly new, also air leaks are most commonly found around the back plate, carb neck and HSN on TRX engines. I was always very careful turning the HSN because it's in a composite carb which strips very easy, also known to crack on hard impact. I believe in sealing the TRX engine, even if it's running good it will run better!

Rolex you should also be gentle with the HSN on your new 4.6, it's rough on the o rings.

 

[Rolex]

Rolex you should also be gentle with the HSN on your new 4.6, it's rough on the o rings.

I hadn't heard that, SMaxxin. Thanks for that info.
I haven't started it yet. I'm still pimpin' and preppin.
Today I got the receiver, failsafe and hump pack installed. Time to tweak the radio.

 

[shoshe]

Well...................As I mess around with this thing I'm finding that the more I adjust the carb trying to solve this problem the more angry I get, because no amount of change to HSN or LSN makes a difference with the stalling problem!!! I had found that I was setting the LSN wrong (I was using the wrong lip for reference point for factory setting and was WAY too rich. Got that straightened out and have got this thing idling better than it has ever.
I am definitely going to seal the carb, wether it's leaking or not if I seal it it won't. I did strip the HSN on my old motor that was having the same exact problem. That's why I believe it to be fuel, but what leads me away from fuel is the fact that it ran AWESOME during break in and for maybe 1-2 tanks after, now all of a sudden it won't run @ WOT?!?!?!? And please forgive my noviceness (is this a word??) or ignorance but what is the backplate?

 

[bassmaster345]

If your motor is a pull start you will need to remove the pull start to get to the back plate, same with the EZ-start.

 

[shoshe]

Geez you guys are great! Pictures and everything. Thank you I have had that off (old motor). Is a new o'ring enough to seal that or should I use some sort of silicone. I am going to try eveything I can, sooner or later I'll either kill it or cure it. Right now I want to kill it!!

 

[Timmahh]

seal the back plate too. i use Permatex Brand Ultra Copper RTV. very good stuff and is heat resistant, which is important for sealing the motor.