2.5 engine big problems

[dirtyharry]

ok i have a traxxas 2.5 ngine that I'm going to be putting into a boat. i got the engine from a kid and decided to strip it clean it and put new o rings in it. so thats what i did i stripped the motor to the case i took everything out except for the crank bearings cleaned every thing and put it back together. i also took the crab apart and put all new o rings in it then re assembled it. ok so heres the problem I'm test running the motor on a 2x4 to tune it when i get it started it goes NUTS, it tries to red line or max out but the carb is tuned to fact specks. something is deff wrong for the love of god help me someone o and one last thing when i put my finger over the carb it kills the motor as expected.

 

[syphon68]

when you look down into the carb and everything is at neutral can you see the slide? ie is the slide pegged open?

 

[Metalhead Matt]

New o-rings don't necessarily mean a tight seal. Use some copper rtv high temp on the o rings and start from there. Use a tooth pick to apply a small amount cleanly. An engine will run goofy if it isn't under any load, too. Should idle and react to throttle input, though.

 

[Skwerly]

Sounds like an air leak to me. Have you checked and double-checked all the fittings?

 

[Rolex]

Since you have it mounted on a 2x4, I'm guessing you are not running a throttle servo. You need to close the throttle by hand. Just because you have the needles set doesn't mean it will idle if the carb is wide open.

 

[dirtyharry]

thank you everyone so far. ok to anwser all the questions no throttle servo the carb is closed all but 1 mm thers no load on the motor what should i use for that puropse and i operate the throttle by hand but as sune as the motor starts it runs wide open lacking any input from me tommrow I'm going to re check all the gaskets. i belive that the problem is carb related only. if anyone has an other info please let me know I'm open to seggestions

 

[Metalhead Matt]

I believe the 2.5 and the 3.3 share the same carb. They're only about $25 bucks. May want to seal it and get a new carb if you can't or don't want to fix yours.

 

[Rolex]

The flywheel and CB is the only load on an engine idling in a truck, so you won't need anything else.
Unless you have an air leak or a serious carb problem, there's NO WAY it can rev high with the throttle closed.

 

[Scrogg]

You have to have a load on the engine, what you are doing is horrible for it.

 

[dirtyharry]

ok i think its the carb and i do have the fly wheel and cb on it

 

[Rolex]

Idling it that way is fine. Just don't rev it without a load.