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Thread: Proper tuning.

  1. #1
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    Proper tuning.

    Just a quick question. I have been tuning my slayer and i got to the point I was burning glow plugs left and right. I finally went to an asphalt parking lot, went back to the starting point and tuned it to perfection. It ran like a champ. I then took it off road in a field that is cut low. The car cooks across the grass and it is fun . After about 3 minutes, it starts to run hot and the idle gets high again. I pick it up and then move it back to the asphalt and let it cool and it returns to normal. I took the body off to see if it does it still thinking I need to cut more holes in the body and it still gets hotter and the idle is higher after a short period of time. once again, it cools down and then I try it again. I don't want to burn up any more plugs so I haven't let it go that far. I richen the motor up a bit and it seems to help but, how rich is to rich? I am already at about 6 turn out on the HSN and about 1/4 of a turn on the LSN. Thoughts anyone?
    Last edited by Double G; 03-18-2014 at 11:46 PM. Reason: language violation

  2. #2
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    I also am having trouble keeping my tune so i'm just gonna keep tabs. I plan to have an expert show me the ropes.
    Spartan Jet Boat
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  3. #3
    RC Turnbuckle Jr. icepick832's Avatar
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    Your having to give it more throttle when not on asphalt. That's one reason for higher temps. The motor is having to work harder vs a smooth surface. Also make sure your doing your tune at roughly half a tank of fuel. As it gets low it leans itself out. What nitro percentage fuel are you using? If it's 33%, maybe try 20%. If I'm planning on strait up street running I use 33. Bashing around I use 20 and don't run into heat issues. I do not own a slayer but used to own a jato and still have a sport and revo 3.3 for nitro. I figured this was more motor related than specific to slayer so I'd give my .02.
    Last edited by icepick832; 03-18-2014 at 11:05 PM.

  4. #4
    RC Turnbuckle Jr. CarGuy7a's Avatar
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    Quote Originally Posted by icepick832 View Post
    Your having to give it more throttle when not on asphalt. That's one reason for higher temps. The motor is having to work harder vs a smooth surface. Also make sure your doing your tune at roughly half a tank of fuel. As it gets low it leans itself out. What nitro percentage fuel are you using? If it's 33%, maybe try 20%. If I'm planning on strait up street running I use 33. Bashing around I use 20 and don't run into heat issues. I do not own a slayer but used to own a jato and still have a sport and revo 3.3 for nitro. I figured this was more motor related than specific to slayer so I'd give my .02.
    +1 Added surface resistance=more heat. I run mine in grass all the time no problem. The grass has to be very short though with the Slayer. I'm talking so low it's almost dirt. I cut my grass area I run my RC's in as low as I can and I run my mower very slow just in case I start digging dirt with the blades I can raise the deck one click before it damages the mower. I run a touch on the rich side also which helps.

    If your idle stays way up after you cut the throttle your LSN is too lean. Sounds to me like you are running to rich on top and too lean on the bottom by your settings. I set my LSN with a pinch of about 5 seconds. Also like said before tune at 1/2 tank. Fill it up and let it warm up for the first half putting around taking it easy then tune at half tank. The reason behind that is, as the fuel burns off, it takes more pressure inside the tank to push the same amount of fuel to the carb as if the tank was full (less air inside the tank). Problem is the engine only puts out so much pressure, so the more air inside the tank, the leaner it will run. Some nitro RC's it's not as noticeable as others. The Slayer I can notice a change to a certain amount but it's not huge maybe 1/4 turn on the HSN if my tune is close. My Savage 4.6 changes drastically at half tank. Where I tune at half tank on it will barely run when the tank is full (too rich). I have to richen my HSN on that truck almost a full turn when I get to half tank.
    Last edited by CarGuy7a; 03-19-2014 at 01:47 AM.

  5. #5
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    Thanks for all your help. Currently I run the traxxas top fuel 20% nitro. I am tuning the motor with only 1/2 of fuel and like I said, the thing runs great but as soon as I take it off road, it will get to hot after about 6 WOT passes. I do agree that it takes more fuel to run on dirt because I run through a tank in about 15 minutes compared to the 25 min plus I get on a hard surface. So if I got this right, the slayer would not be recommended for field use? Would the T-max be any better or should I just find a smoother off road surface to play on? Should I try a lesser % fuel?

  6. #6
    Marshal Double G's Avatar
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    If all you are doing is wide-open throttle then yes it will get hot. These engines are not designed to see constant prolonged full-throttle applications. Change up your driving style and you may find that your temps will be in check.
    The Super Derecho

  7. #7
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    I was using that as a reference. Yesterday, I ran back and forth twice so 4 WOT passes. Then I was putting around 1/4 throttle for a bit and then I would go back to asphalt because I noticed the change in the idle RPM.

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