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engine won't stay tuned

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benjman420

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Everything seemd fine for about the first hour today, the truck was tuned nicely and I was hitting good jumps. At first I just noticed the acceleration was a little sluggish for a second, then was fine. After a few more jumps it was extremely sluggish and seemed really rich(i think?), I tried to lean it out a bit, but it still didn't want to accelerate. So i turned it off and reset the hsn to 4 turns out. The truck fired right back up and just needed a minor adjustment of the hsn. Until I hit another jump, and the same thing happened. I went through this same cycle 5 or 6 times. It seems like the hsn won't stay where it's set, so i'm thinking maybe I stripped it? What do you guys think?:ponder2:
 
Is the needle really easy to turn? It should have some resistance on it. If it's really easy to turn it could just be vibrating loose.


Or, you could have an air leak somewhere.
 
the needle is really easy to turn. Is there any way to stop it from vibrating loose?
 
I don't know if it will work but I think if you clean off the rubber o-rings on the needle it might make it sit tighter. There may be oil or something on the gaskets causing them to not hold like they should.

Make sure you gently seat the threads and make sure they aren't cross-threaded when you put it back in.
 
which engine is it 3.3 or 2.5r if its the 2.5r have fun those engines are horrible for holding a tune

but yeah i would sheck for a proper seal on your needle sounds like its viberating loose also check and make sure you have a good seal between carb and the case
 
I took the whole carb off and cleaned the hsn needle as well as everything else. After putting it back together again and spending some time retuning, the ruck ran quite well.
Unfortunately this time after hitting a few jumps the rear shocks blew out. The caps all came off, but the threads don't look stripped and there is oil everywhere.
Since I can't afford new shocks at the moment, can I put the stock shocks back together with new oil? Also what weight oil should I use(i'm mostly just hitting jumps in my backyard and on the street)?
 
You should be able to put them back together with no issues as long as the threads are good. I used 45 weight oil in my rear shocks. 40 is the stock weight.
 
Before taking the carb apart.. Have you sealed it? I mean have you sealed the carb neck and back plate?Those are common places for engines to leak. For a carb to be the issue, it normally lands on the user tightening down to far and tearing the orings.

Try sealing the two areas with High Temp RTV silicone. I like the blue or red color. DO not tighten down to far till they cure then go ahead and tighten once they have fully cured.They need to cure overnight.
 
yeah if you have the traxxas shock tool you can get them on there pretty tight and shouldnt have any problems but i would start looking into an aluminum bodied shock sucks as the big bores to prevent it from happening again
 
Being a newbie i'm not really sure what the carb neck and back plate are.
I'm planning on getting new shocks towards the end of the month, i just need the ones i have to work until then.
The only thing i had tightend was the HSN. After cleaning it off though the truck seems to hold it's tune pretty well.
 
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The backplate is the flat part on the very back of the engine where the pull start or ez-start connects. The carb neck is the part that goes inside the engine. When you loosen the locknut and take out the carb, the part that comes out is where you seal.
 

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