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proper break in/ tune question

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mclouth623

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whitehall michigan
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  1. Bashing
I bought a 2.5 tmaxx used and can not for the life of me get it going properly so I'm thinking its time for the rtr 3.3 that came with another truck to go in it, so my question is there any specific out side air temperature that is best to break in a new motor? Or if some better in sight on tuning could be thrown out here I appreciate that too. I've tried the stock settings and cannot get it to idle or run it does have reverse. Some times when I do get it to idle the trans acts like its chattering or lunging forward.

Thanks in advance for any advice or input on my situation.
 
Theres a great section for engine sealing I think you should take a peek at. Traxxas is notorious for motor airleaks. While looking at the how to seal take a look at the tuning chart as well. Quite informative!!!
 
Phins Fan said:
Theres a great section for engine sealing I think you should take a peek at. Traxxas is notorious for motor airleaks. While looking at the how to seal take a look at the tuning chart as well. Quite informative!!!
Click to expand...

I've looked at the tuning chart and I'm still having trouble getting it tuned. As for the air leaks I had no idea ill have to look at that.
 
The trans issue is normal on that model. Your engine probably just needs tuning, but it's wise to tear it down and seal it first. There are many tutorials here and elsewhere that cover the process.
 
mclouth623 said:
I bought a 2.5 tmaxx used and can not for the life of me get it going properly so I'm thinking its time for the rtr 3.3 that came with another truck to go in it, so my question is there any specific out side air temperature that is best to break in a new motor? Or if some better in sight on tuning could be thrown out here I appreciate that too. I've tried the stock settings and cannot get it to idle or run it does have reverse. Some times when I do get it to idle the trans acts like its chattering or lunging forward.

Thanks in advance for any advice or input on my situation.
Click to expand...

as far ad the truck lunging forward your idle is to fast or the throttle trim is set wrong, if you can't keep the truck running it may be way lean. try making the high speed mixture a little more rich
 
Ok so I'm going to reseal the motor and give it another go at tuning.

Is there any insight on breaking in the new motor if resealing and tuning doesn't work on the 2.5 I'm just going to put the new 3.3 in it and rebuild the 2.5 later.
 
there is a couple different breakin methods. 1 is where you run it slow with the top off for the first 2 tanks and then you gradually go faster with each adittional tank I think that last for like 5 tanks i beleive and then there is the method of setting it on a stand where nonee of the wheels touch the ground and you let it run,(not sure how many tanks and if there is anything else involved in this method) I use the first one everytime and kinda extend it to like 10 tanks of babying it.... I am sure there is a few things on this site that explains it too.
 
For the stock settings on the carb turn the screw clockwise far as it goes *NOT TIGHT* the back it out 4 full turns counter clock wise. for the low speed needle witch is located on the arm of the carb thats opened up by the servo needs to be flush.

Break in, traxxas DVD's dont say to do this but i personally like to let the engine idle through a tank of gas. putting 1 drop of 3n1 oil into the glow plug hole really helps the engine move. When you first start a new engine its really gonna want some lubrication before start up. so like i said just a drop of 3n1 then prime n start for a second the smoke will be almost a white color from the oil but it will fade back to the blue color.

After the first tank of idling i would just follow the instructions in the DVD. And also, 3n1 oil is a great after run oil. after done for the day just put a drop in carb and glow plug hole. when you next start it up it will run very smooth.

As for the idle.. there is a small polished screw under the HSN opposite side of LSN and that little screw is your idle.. that screw determines how much the carb is open when its closed.. you do want its just barley open when your not on the throttle. if its open more it will just creep forward all the time. Also, while the truck isnt running the first thing i would do is turn on your truck then radio and see if you hear a buzzing sound. If you do you need to slowly adjust your Throttle trim till the buzzing goes away.. then you know your throttle servo is set. so then you need to work on the things i said earlier.

Good luck with you next truck!!
 
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Do not do this^.

The engine should be kept warm as much as possible for the first couple tanks. Start by warming it with a heat gun or hair dryer. Then begin doing what traxxas says to do in the manual....which is drive slowly, stopping and starting etc.

There's really only 2 things that are crucial to a good break-in. Keep the engine warm (200-ish) AND rich. Running warm and rich can be hard to do so you may have to wrap the head with something to keep it warmed up. Too cool and the sleeve will be squeezing the piston too much.
 

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