Takes off on start

[bplakers]

My Traxxas 3.3 is taking off when it starts. Quite fast too. I was just wondering what could be causing this? I just replaced the crankcase on the motor. Then after that it started doing it. It's only been started twice since and hasn't made it more than 30-40 feet with out dying.

---------- Post added at 11:52 PM ---------- Previous post was at 11:51 PM ----------

I just started it up and it took off.

 

[hamz9561]

Have checked for air leaks? How about the carb's idle air gap (should be about 1 mm)?

 

[bplakers]

I tried it this morning it was started fine was running good. Then the servo came off of the carb. Since then I haven't been able to get it to fire.

 

[truggy83]

are you trying to start it without the servo throttle linkage hooked up? Do the wheels spin when you try and start it?

 

[bplakers]

Yeah I have the linkage hooked up now. I did try to start it without it before I noticed it. Prior to that it started up without wheels spinning. I was having to give it a little throttle on the control to start it. After I had it started I messed with the throttle on the control and it was running good. Before I messed with the throttle on the control as soon as you would try to accelerate fast it would die. Was just putting around. Then I messed with the throttle on the control and it started to run alot better wasn't dying could stop with out dying. Haven't been able to get it to start since the carb came off the linkage.

 

[truggy83]

can you set the needle settings back to stock. That should atleast get it to the point where we can tackle the running off problem. If the LSN was adjusted wrong it could cause the idle to speed up which may cause the car to take off on its own. Also probably why it won't start now.

 

[ThEnItRo1]

if when u accelerate nd it dies ur running the motor to lean, if u richen the motor out the motor wont die. I've had that problem with my nitro.

 

[MaxxJTmasheR]

id go back to factory setting on the carb, it happened to my t maxx after messing with it for years it was just way out of wack, after that id check your idle screw gap, realign your linkage on your servo make sure the trim on your radio is centered. id go through all that before you start sealing up the motor but it should be done anyway

 

[bplakers]

I wish I knew what factory setting were for the carb. I just got done working on my car about half hour ago. So I'll prolly tear into my nitro tomorrow. Should the carb be pointing straight or at a angle? I put it on at a angle so I could connect it to the servo. Also when I push on gas the servo will raise up is that normal?

 

[truggy83]

sounds like the carb is not properly aligned. The servo should not pull up when you move it. Could you possibly get a picture or even better a video of what is going on.

---------- Post added at 6:05 AM ---------- Previous post was at 6:03 AM ----------

I'm pretty sure the HSN is 4 turns out, LSN is flush against carb body, and idle 1mm - 1.5 mm...haven't touched my needles in a long time so i forgot a little bit...but I'm pretty sure its right

 

[bplakers]

How do I put a video on here?

 

[truggy83]

you can upload the video to youtube and you click the little globe button on the reply to message box. Past the link for the video into there

 

[bplakers]

[ame="http://www.youtube.com/watch?v=77I2bySbxBY"]MOV0012A - YouTube[/ame]

[ame="http://www.youtube.com/watch?v=x2nt2kuHfx4"]MOV0013A - YouTube[/ame]

I think that'll work maybe. One was trying to get what it sounded like when trying to start it.

 

[truggy83]

hmm I don't really see the servo moving up and down in any of the videos. I did see the throttle linkage bend up alittle bit. Is that what you are talking about? There should be a little tiny set screw that you can loosen where the linkage meets the carb slide. If you loosen the set screw you can adjust the angle of the carb linkage ball cup. I would loosen the screw and turn the ball cup a little bit and test it out by pressing the throttle on the transmitter. Your goal is to find the most natural position for the throttle linkage ballcup in proportion to the throttle linkage itself. You want it to move smoothly without binding. Once you find the right angle, tighten down the set screw and test it.

 

[bplakers]

ya i couldn't get a very good video of it. the 2nd one was supposed to have sound but it didn't. I'm going to tear it down tomorrow try to get everything in the best position put a gasket on my servo. Can i loosen that screw when I put it into the car to put it in the linkage? Cause that was why i had the carb at a angle to be able to get the slide on the carb into the linkage.

I was also thinking of just sealing it up tomorrow do you think I should get it running first then seal it up or seal it up and wait for it to set then get it to run? I don't have any green slime for the carb though I'm waiting on it to come in the mail.

 

[Greywolf74]

Check your clutch shoes too. worn out clutch shoes will make you car move as your starting it up.

 

[truggy83]

You can loosen the screw, put the engine in and than retighten as long as you can still access the set screw when the engine is in place. This would be the best way to do it that way you can test movement of everything and than lock it down when right. If you can't access the screw while the engine is in the car you will have to take the engine out first to get to the set screw. If thats the case, take the engine out loosen the set screw. Test fit the engine back in place, hook up the linkage. Rotate the carb slide ball until it is in best position allowing the throttle linkage and brake linkage to move without binding. Remember the exact angle the ball cup was at, take the engine back out, set angle of ball cup to where it needs to be and tighten it down.

If you plan on sealing the engine, I would probably wait until the sealant arrives before putting anything back together. That way you don't have to take it apart twice.