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  1. #1
    RC Racer
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    new engine won't idle or start without throttle

    hi there. just built my new 3.3 engine for my tmaxx (after the old one blew up) carby is set to factory. the engine won't start or idle unless I'm giving it some throttle. what's the issue with it? straying to get over spending more time fixing instead of using my tmaxx. new glow plug, crank case, carby, piston and sleeve, bearings, cooling head. only thing original is the crank n ez start adaptor

  2. #2
    RC Champion
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    Have you pulled off your air filter and checked you're idle gap?

  3. #3
    RC Racer
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    yep done that. it's seems a bit too open. but as soon as I let my finger off the throttle it dies

  4. #4
    RC Racer
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    awesome now the engine has seized..... piston is locked in the sleeve... my $236 dollar hsp has been more reliable then my traxxas....



    *Watch the language and edit out words that have been replaced by the word filter*
    Last edited by Double G; 01-27-2013 at 03:03 PM.

  5. #5
    RC Champion
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    Quote Originally Posted by B3nno8 View Post
    awesome now the engine has seized..... piston is locked in the sleeve... my $236 dollar hsp has been more reliable then my traxxas....
    Relax, it's nothing major. It can happen with all nitro engines when they're new, just heat the block with a hairdryer and turn the flywheel to free it.

    Edit: Also remove the plug and make sure it's not flooded.
    Last edited by Double G; 01-27-2013 at 03:02 PM.
    Revo.27TX/Jato.18/Maxx523/Maxx3.3/GMAXX/Rusty/ERBE

  6. #6
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    As johnny5c says "Relax". Have you checked to be sure the piston is not just stuck at TDC (Top Dead Center)? Pull the plug and look in the hole, if you see the piston right there then it's stuck. It should rotate off TDC without too much effort but you might need to heat it a little.
    Now for the factory settings... I use those as a starting point and "fine tune" the motors from there. Keep in mind that both the outside temp and humidity will affect the performance of your motor and you will need to tune accordingly.
    Good luck

  7. #7
    RC Turnbuckle Jr. Snook Man's Avatar
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    Quote Originally Posted by B3nno8 View Post
    the engine won't start or idle unless I'm giving it some throttle.
    Make sure you installed the piston with the cutout in the skirt toward the front/carb side of the engine or you will never get it to run correctly.
    No slipper/tall gearing/power = broken parts.

  8. #8
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    +1 to what snook said. My buddy put his in backwards. It would not start without throttle, and would not idle. Also make sure the oil hole in the con rod faces to towards the carb.
    T-maxx 3.3
    Rusty 2.5r
    Summit VXL
    Nitro 4-tec

  9. #9
    RC Racer
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    the piston was just stuck in the sleeve hard I had to pull the engine down to get the piston unstuck from the sleeve. cheers for the heads up on piston orientation aswell I'll double check the position and go from there.
    Last edited by Double G; 01-27-2013 at 07:43 PM. Reason: language, again

  10. #10
    RC Champion
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    Try raising your idle.
    "I like rc cars"....."WHAT? YOU'RE KIDDING!"

  11. #11
    RC Racer
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    had the piston back to front runs perfect... apart from the slipper clutch which constantly disintegrates.... is there a better par or clutch system that doesn't constantly need replacing? I was only on the break in procedure and the clutch shoes have disintegrated again....

  12. #12
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    Hello everyone, i too am having this problem with my 3.3. I bought the truck used and i had several gallons ran through it so i took it upon myself to tear apart the engine and check everything, clean it up and seal the back plate. Everything was perfect besided a tad bit of rust on the piston head. After i got it back together i bought a new carb because the old one was cracked. Ever since then i tried everything and it will not start or idle with out throttle and stalls when brake is applied. Ive tuned it perfectly and no matter how much i adjust the idle gap it will not idle. Ive changed the glow plug several times and even changed to the traxxas 20 percent top fuel since the fuel that came with the truck was crap. Im wondering if i might have the piston backwards??? But will that cause the engine to stall when brakes are applied? Ive about had it with tuning it. Im getting a revo 3.3 in a few weeks so if i cant get the maxx running than i might just sell it. Any suggestions would be extremely appreciated.

  13. #13
    RC Turnbuckle Jr. Snook Man's Avatar
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    1st check the idle gap. It should be 0.7mm to 1mm at idle and the gap should not close any further when the brake is applied, if it does then the idle screw needs adjusted so it will not close past the recommended gap.
    Do the wheels spin when you try and start it if they are off the ground? If they do, the engine clutch may have a problem and is dragging causing the stall.
    If your not sure of the piston orientation or did not know which way it should be installed, it would also be best to remove the back plate and have a look to be sure. It will not run or idle correctly if the piston is installed backwards.
    No slipper/tall gearing/power = broken parts.

  14. #14
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    Quote Originally Posted by B3nno8 View Post
    had the piston back to front runs perfect... apart from the slipper clutch which constantly disintegrates.... is there a better par or clutch system that doesn't constantly need replacing? I was only on the break in procedure and the clutch shoes have disintegrated again....
    Do you mean the clutch shoes, which are attached to the crankshaft of the engine, or the slipper clutch, which is between the large spur gear and the transmission? If it's the clutch shoes, then you can upgrade to the Buku set, if it's the slipper clutch, there are aftermarket ones, but they aren't really necessary. The slipper pads should never burn out if you have it adjusted correctly.

  15. #15
    RC Turnbuckle Jr. Wildman4910's Avatar
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    If your destroying the slipper clutch then you have a problem.

    For the Revo spec slipper make sure the spring washers are installed like this ( ) not like this ) (.

    For both style slippers check the steel friction plate(s) for damage/gouges in it.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  16. #16
    RC Racer
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    if it won't run or idle it will be your piston being installed back to front (had the same problem and changed the orientation of the piston and it works perfect)

    I have replaced the slipper clutch about 3 times it keeps stripping the shoes off the mount plate (which gets replaced with the slipper clutch kit) the washers are installed as it states in the instructions and it's tight to the point where u can move it slowly... happens every time I go to accelerate it blows the slipper shoes off. .. is there an upgrade shoe or system I can instal because this is annoying

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