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View Full Version : Traxxas carbs: 4 turns out, not 2.5


PeterV
02-08-2007, 10:30 AM
A bit of advice in our April 2007 issue's "Engine Tuning Guide" feature caught Traxxas' eye. For those readers who can't even get their engine started or running long enough to do any tuning, the article suggests setting the carb's high-end needle to the "stock setting," or 2.5 turns out as a default setting if you don't have a manual. Although the article is not specifically about Traxxas engine tuning, Traxxas is concerned by our advice because they recommend 4 turns out as a default setting for TRX engines (the engines so many of you have!). Naturally, we suggest you follow Traxxas specific advice over our "for most engines" advice, if you have a TRX engine. Here's Traxxas' official word:


Attention Car Action readers! Carb Tuning News. We found an error in the Engine Tuning Guide of the April issue (page 154) of Radio Control Car Action. While the article states that the default settings for ‘most cars’ is 2 ½ turns, for the Traxxas carbs on TRX 2.5, 2.5R and 3.3 racing engines, 4 turns is our default factory setting. Traxxas carburetors are preset at the factory using precise methods. If the factory settings for the high-speed needle are lost, then Traxxas recommends setting the high-speed needle to 4 turns out (counterclockwise) from closed. Always tune the engine starting from a rich setting and gradually move towards a leaner setting. In most cases, a high-speed needle setting of 2 ½ turns out as specified by the RC Car Action tuning article (April 2007, p 156) will be overly lean and will cause tuning difficulty, drivability problems, and engine damage. For more information about correctly setting the fuel mixture for Traxxas engines, refer to your Traxxas Owners Manual or get precise Factory Tuning settings with the Traxxas Knowledge Center article found at this link: http://www.traxxas.com/support/index.php?action=artikel&cat=88&id=450. You may also contact Traxxas directly at 1-888-Traxxas.

balang_479
02-08-2007, 12:57 PM
My current carb setting on a Sirio is 6 turns out... and any more and it will blow up, im sure its fine as the power i get out of it is better than most engine at the races i go to so the setting is right...

if i went to 2 1/2 turns, the engine would cease.

PeterV
02-08-2007, 01:47 PM
Again, the article suggests that if you can't even get your engine to run, and you don't have a manual to tell you what the default needle settings are, then try setting the high end at 2.5 turns out. Once your engine starts, you can then tune it to wherever it needs to be. We don't say "set at 2.5 then go nuts, because that is the perfect setting for every engine."

balang_479
02-08-2007, 02:19 PM
Again, the article suggests that if you can't even get your engine to run, and you don't have a manual to tell you what the default needle settings are, then try setting the high end at 2.5 turns out. Once your engine starts, you can then tune it to wherever it needs to be. We don't say "set at 2.5 then go nuts, because that is the perfect setting for every engine."

Oh yeah im sure... is was just point how some carbs are designed for completely different tuning "scales" we could say, im sure the 2.5 out is good for most engines (was for my old TR-15)

PeterV
02-08-2007, 02:21 PM
Thanks Balang!

Kuldeep
02-08-2007, 11:40 PM
Well it isss winter.. Juu gotta run extremely rich.

Wardy24
02-09-2007, 11:52 AM
your definatly right about the traxxas engines needing to run more "raw" i have a 4tec i got for xmas and it took me all this time and an artical about the 4tec to understand i need to be at about 4.5 turns.....the hing hauls now....if only i oculd get it to kick into second gear at the right time, i would be set.....

WheelNut
02-09-2007, 02:07 PM
Yeah, just turn it 2 and half turns out. Thats what I tell everybody, business is good at the hobby shop. :p

Wardy24
02-09-2007, 03:18 PM
2 and a half turns out for the transmission? forgive me for being nieve as i am new but if i close it all the way (turning clockwise) 2.5 turns counter clockwise shoudl set the transmission?

spiderwc
02-09-2007, 07:41 PM
no your high speed carb needle.

RControl Freak
02-12-2007, 09:07 PM
I've always had to fight with my engine, and that little thing has been through hell and back! It took a trip into a saltwater bay, and is still ticking! Hats off to Traxxas for building one hell of an engine! (I've got the standard TRX 2.5) :D

fezzy
02-13-2007, 02:22 PM
In the UK 4 turns on the HSN is way too lean, I always start by re-setting 2.5/2.5R's to 5 1/2 turns initially and at this setting they're only slightly rich, once you get down to about 5 1/4 turns they generally start to feel tuned. Obviously our climate differs greatly which is going to be a large part of that, but 4 turns on the HSN for the initial running in process leads to many dis-satisifed customers.