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  1. #1
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    Losi 3.4 Carb settings, etc etc

    Ok so I just bought a LOSI 3.4 carb from amain....couple of quesitons:

    1. Anyone have good initial settings for this carb? I've heard the Traxxas settings aren't correct with this carb.

    2. Any mods at all needed? I've heard no, but some people say they have to do some sanding to get them to fit the throttle linkage.

    3. Does it need to be sealed or just put it on and tighten carb screw?

    Thanks for any inputs/expeierence....I have heard these carbs really wake up the 3.3 and are very easy to tune. None of that low speed bog you get on the Traxxas carb.

  2. #2
    Marshal Double G's Avatar
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    This is bordering the line of support for aftermarket products but also involves fitting into a Traxxas vehicle.
    I would suggest reading the thread(s) in the Slayer forum regarding this topic.

    1. Stock Losi settings; Traxxas settings on the Losi carbs are way too rich. Search Losi's site for support on that.
    2. Some sanding of the carb base assisted in allowing the carb to slide in. I had to modify the Revo linkage for it to fit in my truck.
    3. I sealed it because I found a crack in it.

    Engine sounds more healthy and runs beautifully; and this engine has a piston and sleeve from different engines and the sleeve was repinched. When this one blows I have a new piston/sleeve waiting.
    Last edited by Double G; 04-30-2013 at 02:25 PM.
    The Super Derecho

  3. #3
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    why is this carb so much better the the stock one of traxxas? im sure there diff but from the looks it the same just asking b/c im looking into getting them for my revo and jato

  4. #4
    Marshal Double G's Avatar
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    Quote Originally Posted by jwc0108 View Post
    why is this carb so much better the the stock one of traxxas? im sure there diff but from the looks it the same just asking b/c im looking into getting them for my revo and jato

    Read this:

    Quote Originally Posted by Double G View Post
    I would suggest reading the thread(s) in the Slayer forum regarding this topic.
    The Super Derecho

  5. #5
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    Follow double G advice guys... My Jato flies with the carb and I got all my info from that long thread so go read it...

  6. #6
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    Can't find any Losi carb setting information in the Slayer forums. Or at least not obvious. Can somone post a shortcut to this? Thanks. I hope this carb is as good as everyone says. This could be my last straw for Nitro if this carb doesn't work. Getting tired of having to constantly adjust. Just want to run it for once without spending money.

  7. #7
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    ive been looking to with nothing. i did just put and order in with amain for the 3.4 carb im hoping it is as good as everyone said
    this was the one ive been reading on
    http://traxxas.com/forums/showthread...3.4+carburetor
    Last edited by jwc0108; 05-01-2013 at 12:36 PM.

  8. #8
    Marshal Double G's Avatar
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    Quote Originally Posted by rowdyrich View Post
    Can't find any Losi carb setting information in the Slayer forums.
    Since Losi makes the carb, head over to Losi and see if you can find it there.
    The Super Derecho

  9. #9
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    My TRX 3.3 runs like a champ with the losi carb and after 2 gallons now I am STILL YET TO TOUCH MY NEEDLES... When you find the sweet spot your jato will fly... Temps 210 max. I have stripped tranny's twice now... You will not be disappointed... I actually have an OS .21 brand new sitting since last year as I planned to just kill the TRX motor as I have blown up two since I bought my Jato an Tmaxx... Believe me... You will wonder what happened when your TRX 3.3 changes character and runs as good as anything in its price point and better out there...

  10. #10
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    Got it on. To late to try tonight' but will follow up when I run it.

  11. #11
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    Quote Originally Posted by rowdyrich View Post
    Got it on. To late to try tonight' but will follow up when I run it.
    mine should be in tomorrow let me know how it goes

  12. #12
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    LOL Hmmm I wonder who figured that deal out and tested it.

  13. #13
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    Quote Originally Posted by slayer17 View Post
    LOL Hmmm I wonder who figured that deal out and tested it.
    One of many who have toyed around trying different carbs on TRX engines...

    Ohh, don't get too full of yourself, plenty of others have tried other carb combos... j/k

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  14. #14
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    LOL only if you realy knew
    Quote Originally Posted by Nitronaught View Post
    One of many who have toyed around trying different carbs on TRX engines...

    Ohh, don't get too full of yourself, plenty of others have tried other carb combos... j/k


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    Quote Originally Posted by Nitronaught View Post
    One of many who have toyed around trying different carbs on TRX engines...

    Ohh, don't get too full of yourself, plenty of others have tried other carb combos... j/k

    This data was done back in march by slayer17. Very informative testing.

    OK I found a nice cheater deal that works. I tested it and it realy wakes up the 3.3, its a 100% bolt in with no modfications. It looks 100% like the traxxas carb but it is not. It's 6.9mm vers the stock traxxas 5.9mm. It's the carb from the Losi 3.4 engine and its cheap your looking at 38 to 45 dollars. You could bolt this deal on and have the best look at it and they would never know it wasnt the traxxas carb unless they took it off and messured it. LOL and just for you smarty pants people Yes I know the high side needle deosnt look like the traxxas. You can take the high side needle from the stock 3.3 and bolted it up and worked great if you had to do that.

    FASTEST "recorded/proven" JATO'S-3.3 AND Big block

  16. #16
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    Update:
    Let me just say if I had a mountain top I would scream it from there. If I was a preacher I would preach it from the pulpit. If I was president of the United States I would set up a press conference and tell the American people. If I was a salesman, this is the only product I would sell. Buy this carb, install it, tune it, never look back. End of discussion. Thank you Slayer for your insightful input....Everyone else, buy it. Nothing more to say except wow what a difference a carb makes. Love this thing.

  17. #17
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    Install steel gears. Keep your spur plastic though in case your drive line gets jammed somewhere and you will be good.

  18. #18
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    You guys got a part # for the carb on amain? So this is a direct fit, so no mods whatsoever? I'm thinking of putting one on my jato 3.3. Can I use the factory linkage or mod one.
    ERBE/JATO 3.3

  19. #19
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    Yup,,,,, direct fit. No mods. No bull.

    Here's a link.

    http://www.amainhobbies.com/product_...osi-Carburetor
    FASTEST "recorded/proven" JATO'S-3.3 AND Big block

  20. #20
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    Quote Originally Posted by bswift View Post
    This data was done back in march by slayer17. Very informative testing.
    The 3.3 has been out a lot longer than last March. Plenty of others have installed the O.S. 11k or the Rb carbs on their engine or even tried others. Nitronaught probably has done so also; slayer's has shelled out cash for other carbs and was nice enough to do a write-up.
    The Super Derecho

  21. #21
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    The Traxxas 3.3 is a GREAT engine, all it needs is a better Carb. Thanks to all the folks who experimented and posted their findings...

  22. #22
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    You will have to sand the base a bit. Not much. No you don't have mod anything else, at all.

  23. #23
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    Quote Originally Posted by rowdyrich View Post
    You will have to sand the base a bit. Not much. No you don't have mod anything else, at all.
    Is this for the losi carb or the RB concepts?
    ERBE/JATO 3.3

  24. #24
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    Im not sure because I never had to sand either carb. The only thing I had to do was on the 523 and that was to grind a little angel in on the base for the fly wheel clearance
    Quote Originally Posted by DoubleEagle View Post
    Is this for the losi carb or the RB concepts?
    Last edited by slayer17; 05-05-2013 at 10:38 PM.

  25. #25
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    I was speaking on the Losi carb. I had to sand the base a bit, not much. Set the needles and haven't had to mess with them as of yet.

  26. #26
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    after reading this i ordered the losi 3.4 carb, took me about 5minutes to remove and install it ,didn't have to do anything just pushed it down into the engine connect the fuel and trottle adjusted the idle gap, The hsn look lean so i made it flush. Started truck and just kept adjusting till i saw blue smoke (seems the carb comes lean for the 3.3),. I drove it for about an hour and it did not shut off (only when it ran out of gas) this jato now idles sweeet its like having fuel injection no matter how much i adjusted the carb it never stalled. TO EVERYBODY BUY THIS CARB IT WILL MAKE YOUR LIFE SOOOO MUCH EASIER . I consider myself a rookie and hated the 3.3 but now i can appreciate the motor more /hated the 3.3 so much i replaced the revo with a lrp .28 and my other jato has a tm21

  27. #27
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    Will this carb make a 2.5 run better of is it to big of a bore for it

  28. #28
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    Seemed to make a difference with my 2.5r.

    Sent from my GT-P5113 using Tapatalk HD
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    ERBE, Dewalt EMaxx, Rustler VXL

  29. #29
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    Vwdaveb....Can you post a video of it running i want to see how much a diffrence it makes

  30. #30
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    Quote Originally Posted by Double G View Post
    Nitronaught probably has done so also; slayer's has shelled out cash for other carbs and was nice enough to do a write-up.
    I have and many others before me.... Tried the OS carbs, also Associated... Tons of people have done so... That's all I was saying, Slayer17 isn't the first by far who has done such things...

    Some of you should do some searching on an old member mobydickk http://traxxas.com/forums/member.php?24509-mobydickk

    He did his share of carb testing as well as many other things.... http://traxxas.com/forums/showthread...=1#post2291193

    NN
    Robin Williams
    He will be greatly missed...

  31. #31
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    didn't noticed any increase in speed but no more bogging when moving off , and it idles better,not sure if it makes the 2.5 or 2.5r run any better since the story is it was originally designed for those engines and them used on the 3.3

  32. #32
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    Thanks to all that recommended the losi 3.4 carb. Put one on my revo tonight, bolted right in. I can't believe the difference problem is now I can't keep front tires on ground. Lol time for some gear adjusting. I was even doing reverse wheelies. Now to order one for my 4tec.

  33. #33
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    Losi carb factory settings if anyone need it

    >> http://www.imagebam.com/image/7886a7254441683

  34. #34
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    bringing up an old thread... i just installed a losi carb on my revo 3.3. did the above setting work ok as an initial starting point? i've messed with mine (before seeing this) and got it to fire up a couple of times, but when it starts, its WOT. i moved the needles in and out and it either won't start or it's WOT again. i'm only moving them in 1/8 increments.
    Revo 3.3

  35. #35
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    Take your air filter off and look at the slide, if it's open more than 1mm that's your problem. The carb has to be aligned perfectly with the throttle linkage for it to operate smoothly.

  36. #36
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    After reading all of this i placed an order for a 3.4 carb too and im eager to see the difference, mainly ordered it because i also bought a NX nitro kit for my jato and could use the extra gas ��

  37. #37
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    i installed this carb on both my jatos with 3.3 engines, just bolts in no sanding or grinding ,now they hold there tune better and idles no problem never stalls

  38. #38
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    Can anyone confirm that 2 and 3/4 turns out for both high and low needles is the correct "starting point" for the Losi 3.4 carb?
    Thank you

  39. #39
    Marshal Double G's Avatar
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    After reading the owner's manual of the carb I won't deny it...though you could download the carb PDF from Losi's website...
    The Super Derecho

  40. #40
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    Can someone help? I can't seem to get the losi carb ball link to fit into the throttle arm mixer without binding. Th carb won't open fully no matter what angle I try the carb at or the ball link .

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