cocowawa

Hi all,
I recently changed the diffrential gear of my exceed hyperspeed beginners nitro buggy .The gear seems in good position now but my problem is that as soon as I pull start the engine, the car goes to full speed without me pulling the throttle or doing anything ( ALL BY ITSELF) and the servo horn is in place and I tried adjusting it but the car wont respond and also the brakes are not that tough enough. So what could be the problem? (all the parts of my car are in good shape except the gears which I changed recently)

Can it be the needle valve cuz I remember adjusting it a while ago but never tried the car then until I tried it today when it went to full speed by itself?

Thank you,

chevyderek72

You want a 1mm opening in your carb hole. If it wont go that small turn the idle screw out till its 1mm, and then set it so it stays 1mm with braking. And put your hsn at 2.5 turns out and your lsn at flush with the collar. Then tune from there cause those are the stock settings. That will get you running. If your brakes arent strong enough tighten that little black plastic thing that pulls on the brakes. that will make the brakes grab harder.

Pdexter

If you have the same control that I have, I would try looking at the throttle forward/reverse switch. I had that problem before and I fliped the switch on the control to forward from reverse and it worked fine. I had somehow switched it to reverse.

If I remember correctly when I first got it, it was set up to run with the throttle switch on rev (reverse).[:@] Anyhow, if the throttle switch and your set up get crossed some how, it can make the engine go at full throttle.

cocowawa

HEY GUYS I TRIED EVERYTHING U SAID BUT STILL THE SAME RESPONSE ( OUT OF CONTROL SPEED AS SOON AS I PULL START THE ENGINE)

chevyderek72

If there is a 1mm gap in your carb there is no way for it go to faster than idling.

SAVAGEJIM

Well Eat, 1mm can be too much gap. In reality, he needs to consult his manual for the carb opening. In most engines, on slide or rotating carbs, the opening at idle is typically 0.5mm, not a full mm. So whatever his manual says, that is the carb setting he should use for the engine he has mounted in his RC.

NOW, if he put in an aftermarket engine, he needs to set the carb opening according to THAT engine's manual.

I'm not trying to override you, Eat, it's just that when trying to troubleshoot such a run-away problem, he really should put his carb back to factory setting according to his manual. Then work from there.

chevyderek72

Oh no no if im wrong let me know, i dont wanna tell someone somthing wrong because ive heard or know wrong. I just figured when he said it was outa control that it was wide open, at 1mm would get him in the ball part. Personally ive never dont the 1mm trick, i always just get it to where it idles good. But then again ive gotten pretty good at tuning.

sharkattack99

have you made sure that your throttle trim on your controler is centered? and not making it WOT when you turn it on? thats happened to me a couple of times.

cocowawa

I did everything u guys said but am wondering if the cause could be the weak batteries on the controller and reciever

SAVAGEJIM

If your batts are very weak, and the servo is in the WOT position when the RX loses power and cant return the servo to neutral position, then yes, it is a batt problem.

However, Radios and RXs have failsafe that would put your servos to neutral, which is idle position for the engine. If your failsafe is not working, warranty your radio. A replacement radio should fix this low batt problem.