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Thread: Baja Tuning Trouble

          
   
   
  1. #1

    Default Baja Tuning Trouble

    Engine: CY 29.5cc
    Exhaust: stock can
    Carb: Walbro 813

    I have been having tuning trouble on my Baja. I think I have found the proper low speed setting at approximately 1 turn open.

    However, the high speed is giving me trouble. It seems to work properly at about 1.25 turns open, but as it heats up it starts to bog at high speed as in the video. Eventually, as it heats up, the low speed idle get lower and lower and it bogs more and more at high speed until it dies. It is then impossible to restart until it cools down.

    Any thoughts?
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  2. #2
    Silver Level BYT Member 28offroader's Avatar
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    Default Re: Baja Tuning Trouble

    You're too lean...
    Stock needle settings are 1-1/2 on high needle and 1-1/4 put on low needle.
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  3. #3
    Bronze Level BYT Member cbaker65's Avatar
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    Default Re: Baja Tuning Trouble

    That isnt the way I tune these type of engines,elavation plays a major role in them,you have to tune them to match each other.
    The way I do it,is you got a baseline set right now to where it will start an stay running.
    While engine is running,off the ground acoarce,open throttle wide open,then turn your h in untill you here the engine
    peak out some,then give it a quick stab on the throttle,if it is slow or sluggish as you throttle then your L needs to be adjusted,
    out,but they need to be tuned together as you go.Thats the way I always tuned my stuff,Is by ear.
    These engines,you can only tune on the carbs only so much untill they wont do nothing at all.Good luck!!
    Just shelf it... GET THE OTHER TRUCK DUMMY...

  4. #4

    Default Re: Baja Tuning Trouble

    Factory settongs are 1-1/2 low and 1-3/4 high. the bogging is from a air leak. Rebuild the carb.
    IF you can't handle the TRUTH jusk keep on TRASH talking. The one who can't prove Im a FAKe is the real phoney!

  5. #5
    Silver Level BYT Member 28offroader's Avatar
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    Default Re: Baja Tuning Trouble

    Quote Originally Posted by Monstertrucker14 View Post
    Factory settongs are 1-1/2 low and 1-3/4 high. the bogging is from a air leak. Rebuild the carb.
    The correct stock needle settings are in my post above, I have no idea why you would post with false settings after the correct was posted.

    After he sets that correctly he can adjust his idle needle to a lower idle. Right now the idle is way to high.
    If he can't get the idle set right with factory needle settings then yes he may have an air leak....but the carb is'nt the only place for an air leak. Head, crank bearings, manifold can all have leaks.
    HPI Baja 5T...29cc
    HPI Baja 5T #2...Currently being built
    E-Revo Brushless...
    Supermaxx Picco27....Gone
    Mini-T...Stockish
    HPI Nitro MT...Waiting for rebuild
    Slash 2wd...Brushless
    Slash 4x4...Brushless
    Venom Creeper...Tekin FXR 35T Pro
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    INTEGY SUCKS!!!!!!!!!!!

  6. #6
    Silver Level BYT Member Positronic's Avatar
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    Default Re: Baja Tuning Trouble

    something not right, check the fuel lines also

  7. #7

    Default Re: Baja Tuning Trouble

    Quote Originally Posted by 28offroader View Post
    The correct stock needle settings are in my post above, I have no idea why you would post with false settings after the correct was posted.

    After he sets that correctly he can adjust his idle needle to a lower idle. Right now the idle is way to high.
    If he can't get the idle set right with factory needle settings then yes he may have an air leak....but the carb is'nt the only place for an air leak. Head, crank bearings, manifold can all have leaks.


    RIGHT FROM THE ZENOAH ENGINE MANUAL?. + - turn. SO . The carb is the first place to start.
    IF you can't handle the TRUTH jusk keep on TRASH talking. The one who can't prove Im a FAKe is the real phoney!

  8. #8
    BYT Loiterer jakel's Avatar
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    Default Re: Baja Tuning Trouble

    Not sure what is happening when you say "as it heats up," is it idling without bogging? Did this motor get a break-in at all? Just wondering if it's sat at idle for a few minutes or so before messing with the needles.


    (edit) also, is the 813 the carb you got with the baja (I think you got it used)? In my experience, that carb can be a bit finicky. Might be better to throw down for a new carb and just start from there, if nothing else seems to work. A lot of guys are running the 990 now, although I don't have experience with anything other than the 813 and the 668.
    Last edited by jakel; 04-10-2012 at 04:53 PM.


    beat it 'til all options are extinguished


  9. #9

    Default Re: Baja Tuning Trouble

    Quote Originally Posted by jakel View Post
    Not sure what is happening when you say "as it heats up," is it idling without bogging? Did this motor get a break-in at all? Just wondering if it's sat at idle for a few minutes or so before messing with the needles..
    my big mistake is tuning it right when i start it. It will idle just fine. Its when after a few minutes of running (3ish), it starts bogging and eventually shuts down and wont start back up until the motor cools down again. I was running fine with my tune a little lean a few days ago, ran a solid 10mn no problem. This is what leads me to believe i just am a tuning n00b lol
    HPI Baja
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  10. #10
    Bronze Level BYT Member cbaker65's Avatar
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    Default Re: Baja Tuning Trouble

    This is just a wild card,But it does seem weird that after it runs an heats up,it just dies..
    Get it started an loosen up the gas cap an see if the engine stays running,It might be
    a preasure issue were the tank builds up preasure causing it to die.
    If that dont solve the problem,then it rules that out atleast....
    Just shelf it... GET THE OTHER TRUCK DUMMY...

  11. #11
    Silver Level BYT Member Positronic's Avatar
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    Default Re: Baja Tuning Trouble

    Quote Originally Posted by Monstertrucker14 View Post
    RIGHT FROM THE ZENOAH ENGINE MANUAL?. + - turn. SO . The carb is the first place to start.
    it doesn't have a zenoah engine

  12. #12
    Silver Level BYT Member 28offroader's Avatar
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    Default Re: Baja Tuning Trouble

    Quote Originally Posted by Monstertrucker14 View Post
    RIGHT FROM THE ZENOAH ENGINE MANUAL?. + - turn. SO . The carb is the first place to start.


    Quote Originally Posted by Positronic View Post
    it doesn't have a zenoah engine
    x's 2!...


    Quote Originally Posted by gbsharon View Post
    my big mistake is tuning it right when i start it. It will idle just fine. Its when after a few minutes of running (3ish), it starts bogging and eventually shuts down and wont start back up until the motor cools down again. I was running fine with my tune a little lean a few days ago, ran a solid 10mn no problem. This is what leads me to believe i just am a tuning n00b lol
    Sorry to say but usually when the motor runs fine cold and does'nt run right when warm, that's a sign of loss compression. More than likely you'll need a head rebuild.
    HPI Baja 5T...29cc
    HPI Baja 5T #2...Currently being built
    E-Revo Brushless...
    Supermaxx Picco27....Gone
    Mini-T...Stockish
    HPI Nitro MT...Waiting for rebuild
    Slash 2wd...Brushless
    Slash 4x4...Brushless
    Venom Creeper...Tekin FXR 35T Pro
    Traxxas 4-Tec...Waiting for rebuild

    INTEGY SUCKS!!!!!!!!!!!

  13. #13

    Default Re: Baja Tuning Trouble

    Quote Originally Posted by Positronic View Post
    it doesn't have a zenoah engine

    That's the problem DOh
    The problem is in the carb. it needs to be rebuilt. Another problem can be the oil mix. Your engine should start in two pull every time if properly tuned.
    I now run amsoil and 50:1 that solved the hard starting problems.
    IF you can't handle the TRUTH jusk keep on TRASH talking. The one who can't prove Im a FAKe is the real phoney!

  14. #14
    New BYT Member Wicked's Avatar
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    Default Re: Baja Tuning Trouble

    1 1/2 on the High
    1 1/4 on the Low

    1 3/4 on High is really rich and in my experience with a few carbs and engines that's isn't going to work.

    Start with the correct settings and make sure your idle screw is touching the carb. Get the engine running and drive it around so its not bogging. If you notice your idle is changing and wanting to die then turn in your idle a little.

    If the video your idle seems really high. Not sure if that's your idle or your needles are to lean.

    O and one other thing. And this is based only from what I can see on the video but whoever is tuning the motor it looks like the person is really turning it. At most from stock seeing you will move a 1/4 turn and that is loads. Move that needle just enough to actually see that you moved it and then try again. You should never turn it like your removing or tightening a screw.

    Good luck.
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  15. #15

    Default Re: Baja Tuning Trouble

    figured out an o ring was missing where the air filter meets carb. Ordered one of those, going to replace it, and set needles to stock and just run like that. If it runs well (relatively) with the stock needles, the problem will be that i suck at tuning lol
    HPI Baja
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  16. #16
    Bronze Level BYT Member cbaker65's Avatar
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    Default Re: Baja Tuning Trouble

    Ye also might want to check or replace the gasket between the carb throat an head,there is a few varibles than can cause these problems,
    like the ones that were mentioned by the other members.But,its good that you get to learn all the symptoms that was mentioned.
    I have 17 yrs exsperince with these types of engines.
    Im in Calif,smog laws effect the carburation on these because the carbs are preset,so everytime a person brings me a weedeater or
    leafblower an chainsaw,I have to cut off the preset caps on the needles,some dont have slots in the needles an I have to cut slots
    in them to tune the carb for my area.

    Good luck,glad you have found the issue...
    Just shelf it... GET THE OTHER TRUCK DUMMY...

  17. #17

    Default Re: Baja Tuning Trouble

    The problerm witrh bogging is is an air leak. The o-ring around the air filter isn't going to fix that problem. The engine is not getting enough fuel. These engines suck lots of fuel.
    IF you can't handle the TRUTH jusk keep on TRASH talking. The one who can't prove Im a FAKe is the real phoney!

  18. #18

    Default Re: Baja Tuning Trouble

    Quote Originally Posted by cbaker65 View Post
    Im in Calif,smog laws effect the carburation on these because the carbs are preset,so everytime a person brings me a weedeater or
    leafblower an chainsaw,I have to cut off the preset caps on the needles,some dont have slots in the needles an I have to cut slots
    in them to tune the carb for my area.

    Good luck,glad you have found the issue...
    There is actually a tool to adjust the needles that dont have a slot in them, but unless your a certified small engine mechanic (like me) you cant legally own the tool.

    Makes me wonder how long that o-ring was missing, hoping the engine didn't injest too much dust causing you to have a compression problem after it warms up.
    Other things to check is the spark, coils have been known to not work after the engine warms up.
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