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Thread: Old tmaxx 2.5

  1. #1
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    Old tmaxx 2.5

    It's been sitting for 4 years or so and i took the engine off and soaked it in nitro for a few hours to clean it took the tank off and cleaned it out has decent enough fuel lines i think i'm about to go try and start it anything i'm missing? Not to sure how to tune it but going to check some videos.

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    Very cool. I would crank the engine over a little before starting with the glow plug out. You want to make sure the carb is clear. I would go back to base settings, high speed needle out 4 turns, and the low speed about 2 out. It will probably be rich but after you get it started, then you can tune it and lean it out some. Take you're time tuning and make sure you don't go to lean, tough on the engine. Do a pinch test to get close while running to help set the low side, dies in 3-5 seconds. Any longer it's rich, any shorter, it's too lean. Then slowly work on the high side,making passes and making sure a smoke trail is visble. Let us know how it runs.

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    I ran it some before reading this and when it starts it doesnt want to sit still I have to push up on the trigger on the controller is that normal? Then when I go to take off if I give it full throttle it wants to cut out does that mean its to lean on the lsn? And honestly not sure which one I turn for the lsn is it the screw on the left of the carb near the blue boot looking thing?

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    Quote Originally Posted by Koreyh View Post
    I ran it some before reading this and when it starts it doesnt want to sit still I have to push up on the trigger on the controller is that normal? Then when I go to take off if I give it full throttle it wants to cut out does that mean its to lean on the lsn? And honestly not sure which one I turn for the lsn is it the screw on the left of the carb near the blue boot looking thing?
    Yep. the LSN is the one inside the end of the slide by the blue boot. Is it smoking while idling? Sometimes you really have to look close. It does sound lean on the HSN. When you adjust these, only move them 1/16 of a turn at a time. Looking down at the HSN, rotate it counter clockwise 1/8 of a turn. Then try a moderate throttle punch again. See if it feels better. If it takes off, make sure there is some smoke coming from the exhaust. If not, this is an indication it's too lean. Bring it back and go counter clockwise another 1/16 to 1/8. DON'T drive it lean.

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    set to factory on the carb... http://traxxas.com/node/50983

    HSN 4 turns from closed

    LSN flush with carb, or what i like to do is 2 1/2 turns from closed, just be careful closing your LSN you can damage it if you torque it to hard after its closed

    Idle gap 1mm when looking down the throat of the carb...
    Traxxas is good, but so are other Manus

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    I'll try this tomorrow thanks for the advice it smokes when it gets going when I first ran it today first time in about 4 years it ran I pulled it up and pinched the gas off and looked and it was smoking some is that bad? It didn't smoke after I stopped it the other couple times.

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    what smoked, out the exhaust, or your engine is smoking...
    Traxxas is good, but so are other Manus

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    Sounds like you're doing good. When mine was badly out of tune, I actually held it up (firmly) and just goosed it to check it. Not recommended to rap it up this way, but for a quick burst I didn't have any problems. That helped me get close enough to run it a little, to fine tune it. Mine I ran slightly rich for a tank or two, then I started to lean it out. It had sat for awhile and I wanted to make sure the carb passages were clear and it didn't go lean on me. It also gave me a chance to work through other issues. Mine is slightly rich now, if it sits idling for 30 seconds it will die, but I want that as a safety. Sitting and idling can over heat an engine.

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    It was smoking towards the engine but it only did it that first time could it be from me soaking it in nitro to clean it out?


    Edit:Its been almost 24hrs out of the nitro so im not sure

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    The nitro has oil in it. The nitro evaporated, but leaves the oil. The engine when it heats up will smoke that as it burns off. As long as it doesn't catch on fire lol, it will quit. Now you do want to see smoke from the exhaust as it runs.

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    i agree, sometimes i get some after-run oil around my glow plug hole when im trying to get it down in the engine... itll smoke sometimes from it... so yes its prolly from the nitro fuel
    Traxxas is good, but so are other Manus

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    Probably what it was since it didnt do it anymore ill try tuning tomorrow what should I use to turn the lsn since the tank is in the way.

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    Quote Originally Posted by Koreyh View Post
    Probably what it was since it didnt do it anymore ill try tuning tomorrow what should I use to turn the lsn since the tank is in the way.
    you can get to it with a small flat head screw driver, its just awkward to do...
    Traxxas is good, but so are other Manus

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    I set the hsn and lsn to what you said gonna go run it see if its better also this morning looked like there was condensation in the tank is that normal? I put the original tank and cleaned it up and put it on.

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    Quote Originally Posted by Koreyh View Post
    I set the hsn and lsn to what you said gonna go run it see if its better also this morning looked like there was condensation in the tank is that normal? I put the original tank and cleaned it up and put it on.
    If you've had nitro in it, it's cool. When I sit my jug of nitro outside and the sun hits it, same thing, it condensates. If you think the condensation is anything other than nitro, pour a small amount in it and swish it and discard. Temp change causes this and it's normal.

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    Ok it had nitro I ran it earlier and got it going pretty good is the red switch on the controller for reverse? I can't remember but when I stop and flip it nothing changes

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    Quote Originally Posted by Koreyh View Post
    Ok it had nitro I ran it earlier and got it going pretty good is the red switch on the controller for reverse? I can't remember but when I stop and flip it nothing changes
    yes its for reverse if you have reverse installed... if not itll just do nothing..
    Traxxas is good, but so are other Manus

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    Yep, the red toggle is reverse. It will only go into reverse at an idle, as a safety feature. While the truck isn't started, flip the red toggle and watch the linkage that is attached to the servo next to the steering servo, drivers side of the throttle linkage, I think the stock shift servo is a Traxxas 2018. It has a rod going to a slide, that goes into the front of the trans. If it hasn't been removed for FOC (forward only conversion). In which case that servo and linkage may be gone. You should see the servo arm move forward and backwards.

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    The red thumb switch is for forward/reverse.
    Locate the servo closest to the transmission, with a linkage connecting to
    the transmission.
    If you dont have this servo, there's a possibility someone added a
    a FOC (forward only conversion) kit or, you have a S Maxx, not a TMaxx.

    If you do have this servo, flip the red switch and check the action of the servo.
    Chances are the linkage is not pushing/ pulling far enough to engage and disengage .
    Heres a checklist of potential possibilities.
    http://traxxas.com/support/Reverse-d...ill-not-engage
    Bash, Crash, Upgrade, Repeat..

  20. #20
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    I went out and ran it some and got it into reverse then almost couldnt get it into forward again probably cause it doesnt want to sit still also do the transmissions on these things use any kind of oil?

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    High idle makes it either not shift or really hinky about shifting. Once you get it tuned right and the idle speed set, it will smoothly go back and forth.

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    Yea I need to adjust the idle I guess said something like 1mm idle gap how do I measure that or just guesstimate?

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    Quote Originally Posted by Koreyh View Post
    Yea I need to adjust the idle I guess said something like 1mm idle gap how do I measure that or just guesstimate?
    just FYI a paper clip is aproximately 1mm, and you can also use a 1mm allen key... i do mine by eye because 1mm isnt always what i need, but in the begining this will help
    Traxxas is good, but so are other Manus

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    Quote Originally Posted by Oldrcguy View Post
    Yep, the red toggle is reverse. It will only go into reverse at an idle, as a safety feature. While the truck isn't started, flip the red toggle and watch the linkage that is attached to the servo next to the steering servo, drivers side of the throttle linkage, I think the stock shift servo is a Traxxas 2018. It has a rod going to a slide, that goes into the front of the trans. If it hasn't been removed for FOC (forward only conversion). In which case that servo and linkage may be gone. You should see the servo arm move forward and backwards.
    Not on a 2.5, the 4909 was the only model with reverse and opti drive. On the 4910 you can definitely strip the gears by switching it while it's moving

    Sent from my HTC One X using Tapatalk 2

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    No oil in the transmission, when the truck is new there's a sticker on the trans that says don't oil it.

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    Quote Originally Posted by rcdriver5 View Post
    Not on a 2.5, the 4909 was the only model with reverse and opti drive. On the 4910 you can definitely strip the gears by switching it while it's moving

    Sent from my HTC One X using Tapatalk 2
    Uh nope. The shift hub on a 4910 has a ring on the inside of each side to trap the pawl on the forward and reverse hubs, while it's rotating fast enough to sling outwards and engage, ie while the truck is moving. I know for a fact, I have been in my 4910 trans a number of times. Now there is a mod you can do to let it shift while moving forward or reverse, but few know of it.

    And for Optidrives, they are for the 490X series of gray transmissions, NOT 4910 series of black transmissions. Some 2.5's with optis, some didn't. Generation 3 2.5's had the opti drives, out of 5 or 6 generations of T-Maxx.
    Last edited by Oldrcguy; 03-19-2013 at 04:38 PM.

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    http://traxxas.com/products/models/nitro/4910tmaxxclassic-details
    Forward/Reverse Two-Speed Transmission
    T-Maxx’s fully enclosed transmission features two-speeds forward and two-speeds reverse with a speed-sensitive reverse lockout. It provides racing-truck acceleration in low gear and 40+mph top speeds in high gear. Shifting is hard, fast, and automatic with an adjustable shift point! Just push a button on the TQ-3 transmitter to shift into reverse. Only the patented T-Maxx design allows full proportional control of throttle and braking, along with two-speed shifting, in both forward and reverse gears (patent# 6367345).

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    Anything special I need to clean the air filter with?

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    Quote Originally Posted by Koreyh View Post
    Anything special I need to clean the air filter with?
    soapy water and keep squeezing it in your hand, then rinse it really well squeezing it often, let it dry out and oil it up
    Traxxas is good, but so are other Manus

  30. #30
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    Do you have to use any special kind of oil cause I think I have some k&n air filter oil in the shop.

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