hello,

i have the tower hobbies st-15 nitro truck..i just bought it so the engine is still being broke in. when i start the car up, the motor revs up at full throttle! the tires spin out of control as well. do i have the throttle screw adjusted wrong? also, the antenna wire broke off half way... i can't turn the two front wheels since the wire is broke in half..do you think it's the wire being broke? high and low speed needles are set at factory settings. thanks!

First off....don´t start your truck if you don´t have complete control of it. You will end up smashing it.
Next I think you should check your linkage. You need to take a look down the carb and see what position the carb has when the servo is centered.

try adjusting your idle needle ccw. it should slow down the engine at center servo settings. also, for your attenna wire wont do that, it will just make your truck range shorter. you can always go to the local hardware store, buy some wire, twist it together with the old one(make sure its metal on metal) and extend your anttena. for your wheels, check to make sure the wire is in the reciver box, and make sure there are no cuts in the wire connecting servo to reciever box.also adjust your linkage to a set position that will close the carb more. hope this helps.

or go to towerhobbies.com and buy actual antenna wire for less then 5 bucks

thanks for the help! why do the tires spin when i start it up??? [] the motor revs up so high, i'm afraid the motor is going to blow. thanks. also, does it matter if i leave fuel in the fuel tank for more than a week?

You must not twist two wires together to extend the antenna length. Instead buy the whole wire and solder it back in to place on the receiver. Once you have that fixed we can help tuning your engine.

Although, I do believe you have a linkage problem or the idle screw is not properly set as the engine should idle while the servo is centered.

Ryan

The tires spin because of the centrifugal clutch. The clutch-shoes are held in by a spring and when the engine revs up it makes the shoes move outwards and make contact with the clutchbell which drives the wheels.

In regards to the fuel it is not a good idea to leave fuel in the tank for too long. Nitrofuel is hygroscopic (it attract moisture from the air) therefore when you leave it for a longer period of time it will have become bad leaving you with poor performance and more wear on your engine because of poor lubrication.

how far should the throttle screw be out?

Far enough to keep the carb open about 1.5mm.

Ryan

All so make sure you use after run oil!

easy way to set throttle linkage vorrectly is unscrew the servo horn, that thing that connects to the throttle servo, its most likely black and plastic, then on your radio set your throttle to neutral, make sure the trim is in neutral too. then put the servo horn back on but making sure the carb is closed as far in as possible, you ownt close it all the way because of the idle screw, but just push on the linkage and set the servo horn on the servo making sure the throttle is closed

try this, take the air filter off. then turn all of the electronics on, and look into the carburettor hole ( directly underneath where the air filter was ) pull on the throttle (ie pull the trigger on the controller) and look at what happens. let go of the trigger completely. the hole in the carburettor should close up to about 1 to 2 mm from completely shut. If it does not, try putting the brakes on ( push the trigger towards the front ) if the servo turns but the carburettor doesnt close up, look in the manual for the screw called the idle speed screw, or idle screw, turn that screw anti clockwise slowly while holding the brakes on and the carburettor should start closing up. if it does ( and it most certaintly should ) turn the throttle trim on the radio until the carburettor will close to that 2mm gap you turned the screw to when you are not touching the controller at all, but it is turned on. if this doesnt fix it then reply and explain what happened and someone here will explain to you how to fix your linkage problem.

Dann