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  1. #1
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    engine getting very hot when super rich

    hi, i have two revos one with a after market engine.

    however just bought a new one for my son.

    we broke in the engine and it was good then randomly during the tanks the idle speed would just become inconsistant die randomly and get hot.

    i richen both needles and still the same result.

    we have now completed 6 tanks but during 6 tank it was even worse. dieing, idling high, getting hot, could lower the idle to bring it down and it would just act like idle was too low.

    my HSN is over 6 turns out and revs high very quick(stock rich is ment to be 4 turns out)

    and lsn is 1 turn OUT from flush, no loading up due to excessive richness of lsn just drops in idle then raises like a lean hsn.

    any ideas... no wonder i changed my original engine to an after market. they obvously havnt got any better over the last 2 years.
    Revo 3.3 chassis / LRP .28

  2. #2
    Marshal Double G's Avatar
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    High temps mean lean fuel mixture; so if you are running rich on both the HSN and LSN then I would do an air leak test on the entire system.
    The Super Derecho

  3. #3
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    Hi, I hAve taken out the engine an sealed it. And did the under water test with pressure with the tank and tank is fine. Will try it my luck again today.
    Revo 3.3 chassis / LRP .28

  4. #4
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    ok, so i got it figured out a bit, i just cranked the hsn out anther full turn and it was slightly rich on top
    lsn is just out from flush.

    idle still a bit inconsistant
    Revo 3.3 chassis / LRP .28

  5. #5
    Marshal Double G's Avatar
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    Another thing you may want to verify is that the standard Revo header is known to split right at the first bend where it attaches to the mount. One way to verify this happened is that your rear springs and the chassis in the area will be covered in fuel/oil. It is very hard to see the split but it does happen. I've been trying to figure why I've been having tuning and heat issues even though the header was fairly new. Now I just installed the PE Revo header (just as many others have) and hopefully that will cure it.
    The Super Derecho

  6. #6
    RC Turnbuckle Jr. Nitronaught's Avatar
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    High temps Rich LSN plenty of smoke... Your LSN is probably too lean, making you having to make the HSN overly rich to compensate and run... Factory LSN settings are designed for break in and getting you started, not for regular running...

    Tune that LSN with the pinch test... It's in the link I am providing...

    This will help read it and you shall find your tune...
    http://traxxas.com/forums/showthread....&goto=newpost
    Founder of H.U.A.
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  7. #7
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    i made the LSN richer and it just wouldnt start or hardly run an spat alot of fuel. it was too lean of a HSN, im like 6 turns out, any leaner and temps go up an it acts like a lean hsn...

    im not a "rookie" when it comes to tuning, i've been racing nitro buggy for the last 5 years.

    also nearly every engine manf will tell you to not tune the LSN via pinch test, there is no way it relates to how well a 10second stop and then full throttle will act. you need to tune the engine under normal usage conditions.
    which is where u dont stop every few mins an do a pinch test... a HOT engine at normal operating temperature, 250-275F, should almost die instantly when pinching the line, this is due to the crankcase temperature allowing different levels of volume. the position of the idle screw itself has a great effect on the "pinch test"

    sure the pinch test works but you will get random flame outs, bad idling, killing plugs, poor power from the low end

    This is why i changed out the 3.3 in my other revo to a LRP the quality in the 3.3 just isnt there. sure you get luckly an some dont leak, but most do. Traxxas need a new engine.. of decent quality
    Last edited by Nitronaught; 01-14-2013 at 01:17 PM.
    Revo 3.3 chassis / LRP .28

  8. #8
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Nah,,, You just need to now how to use the pinch test properly... a 10 second pinch test would be for a much larger engine... PLus if you are trying to do a pinch test with your HSN that richm it's not going to work...

    You must go back to factory settings, this time richend the LSN about 1/8th a turn from factory and see what you get..

    The sticky I wrote has been up for 6 years in the FAQ section, viewed well over 70,000 times... Funny, I"ve tons of PM,s and Emails that say different...

    With the HSN tuned somewhere in the ballpark and not so rich try the LSN pinch test in the thread I linked to...

    I've got 4 TRX engines, don't have your problems. Raced them since 2004...

    So It's up to you. You can try the tuning sticky or spend $150.00+ to fix your tuning situation with a motor you are more comfortable with...

    Normal operating Temps as per the Mfr of TRX engines is anywhere between 210-270 degrees F. That also is what other non TRX mfr's state (I could easily name 3 of them).

    Suit yourself but no need to bash an engine just because YOU are having tuning issues...
    If you want help with your TRX engine issue post,,, Wanna bash a TRX product... Don't post...

    Try it, you might be surprised.... Many have been. But if your HSN is way rich your LSN is not going to do right with the pinch test... From Factory settings FIRST tune the HSN as best you can, THEN tune the LSN via the pinch test... It should run 3-4 seconds, no more, no less... The Idle should rise when it stalls if it doesn't often the HSN might be a tad on the rich side...
    After tuning the LSN return to fine tune your HSN and lastly your idle....

    http://traxxas.com/forums/showthread....&goto=newpost

    Try it,, what have you got to lose?
    Founder of H.U.A.
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  9. #9
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    Hi, i just googled this an found this thread is the same issue i am having.

    i just got my revo today, went to start break-in as per the Traxxas revo 3.3 manual.
    My revo just would not start no matter how much i try, had to put idle screw up a fair bit. to start and even idle.

    the first three-four tanks went good, then all of a sudden i had anything over about half throttle it would sound like it was screaming and went strait to really high rpm, went really WARM on temps, as in couldnt get near it with my hand.

    i too had the fix of richening the High speed needle valve up by 12 hours or it would continue to get hot and just choke at idle, the Low speed needle was richend by a few clock hours with no change.

    any suggestions?

  10. #10
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by Finisher View Post
    Hi, i just googled this an found this thread is the same issue i am having.

    i just got my revo today, went to start break-in as per the Traxxas revo 3.3 manual.
    My revo just would not start no matter how much i try, had to put idle screw up a fair bit. to start and even idle.

    the first three-four tanks went good, then all of a sudden i had anything over about half throttle it would sound like it was screaming and went strait to really high rpm, went really WARM on temps, as in couldnt get near it with my hand.

    i too had the fix of richening the High speed needle valve up by 12 hours or it would continue to get hot and just choke at idle, the Low speed needle was richend by a few clock hours with no change.

    any suggestions?
    Did you follow my advice before posting?

    AS stated in the owners manual, factory settings only to get your engine running and broken in... From there, like it states in the book, you need to tune for performance...

    Tuning for performance means you have to do more than just tweak on the HSN... If the LSN is too lean YOU WILL HAVE TO MAKE THE HSN TOO RICH in order for it to run and not burn up. But even then you are going to see smoke trails, high temps, poor performance...

    IF one needle is way off so will the other... See the pics below as they illustrate their relationship with each other.... Then follow the advice I've posted I bet you will find better results. Thousands of others have, no reason why you can't join the "I can tune my Nitro RC" club ... .


    Founder of H.U.A.
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  11. #11
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    Hello, this is second traxxas 3.3 truck. My other is a tmaxx. My Lsn is out from flush too so it's def not lean. I went to factory settings an had to richer the high speed by 1 turn to stop it cutting out. But has good perfomance and temps are 250f From what I'm experiencing could be an air leak?


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  12. #12
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    If I richen Lsn an lean Hsn I get super bog rich down low and then it clears an revs very high an cuts out due to no fuel...


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  13. #13
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    Found my engine case cracked... Will get warranty then consider selling for an electric trx car. Obviously alot less interest in nitro trucks now


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  14. #14
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by Finisher View Post
    Found my engine case cracked... Will get warranty then consider selling for an electric trx car. Obviously alot less interest in nitro trucks now


    Sent from my iPhone 5 using tapatalk
    If it's the bottom end of the crankcase this is probably due to damage in the wrist pin area in most cases I've seen...

    +1 RTR Nitro's are not selling as popular as RTR electrics. Lots of people who are new to RC cars as a hobby go in the RTR direction... But don't be fooled, on the offroad racing circuit, Nitro is holding it's ground quite well in the appropriate classes...

    Is it for everyone? No, but I love the noise, the way it reacts and find that with some drive time under the belt,,, it's no harder to maintain than electric...

    Just learning with a Nitro usually means your first engine is not going to last as near as long as your second since you cut your teeth with tuning and driving on the first one...
    Founder of H.U.A.
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  15. #15
    RC Turnbuckle Jr. kdvanb's Avatar
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    What do you mean?
    Cut your teeth with tuning it?
    Slash 2wd, Slash 4x4, 30th digger, Rustler VXL

  16. #16
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by kdvanb View Post
    What do you mean?
    Cut your teeth with tuning it?
    Your first nitro,,, you have NO points of reference except what you read... You are learning to tune a Nitro RC for the first time... IT's slightly painful as the frustrations can get to you...
    When a baby is cutting it's teeth it's frustrated and not a happy camper sometimes....
    Founder of H.U.A.
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  17. #17
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    Yeah, I'm not new to the nitro world. Just these settings I had to run at were messed up compared to my other 3.3s. But cracked case was my problem.


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  18. #18
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    Quote Originally Posted by Nitronaught View Post
    Just learning with a Nitro usually means your first engine is not going to last as near as long as your second since you cut your teeth with tuning and driving on the first one...
    Isn't this the truth. My poor Nitro Sport's .15 engine never had a chance when I got my little Nooblet fingers on it many moons ago! But with practice, patience, a lot of research and the great guys on the TRX forums (looking at you Nitronaught, Snookman, Double G I've had many years and gallons under all the engines since. Just hang in there and follow the advice of the guy with over 17,000 posts

  19. #19
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    What's the weather like outside buggyandtruck?

    I hate the pinch test, I find it quite annoying. Instead of using the pinch test you can go by how long the engine will idle without 'loading up'. It's easy, if you have the idle gap and hsn set right and running good up top, bring it in and let it idle. If it idles for 5-10 seconds and still has snappy take-off power with no hesitation, it's tuned.
    erbe emaxx 26maxx s27revo 18tmrevo XXL platinum

  20. #20
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    Quote Originally Posted by Double G View Post
    Another thing you may want to verify is that the standard Revo header is known to split right at the first bend where it attaches to the mount. One way to verify this happened is that your rear springs and the chassis in the area will be covered in fuel/oil. It is very hard to see the split but it does happen. I've been trying to figure why I've been having tuning and heat issues even though the header was fairly new. Now I just installed the PE Revo header (just as many others have) and hopefully that will cure it.
    Hey is this what you mean about discoloring?? I'm having heaps of issues tuning - running to hot, blowing plugs after a couple of tanks. even on standard settings! I haven't spilled anything on the header, that Colour just showed up.
    I hope it's a split because it'll will save me a lot of frustration

  21. #21
    Marshal Double G's Avatar
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    The likelihood of a T-Maxx splitting a header is pretty rare. Check the head bolts and the screws holding the header to make sure they are tight and that the silicone adapter is not split.
    The Super Derecho

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