jeremy sawatzky

HELP!!! My engine is so messed up!! it gets into the 320 degrees on factory settings in 5 minutes! I have to richen the hsn a whole bunch before it gets down below 270. Once i tuned it and it got too rich and the revs. got too low for it to shift into 2nd gear. After i let it cool i took it for a spin agian and the settings were completely opposite, and i didnt even touch any of the needles while it cooled.
The engine doesnt seem to have the power as it used to either. is that a tuning problem or is my engine shot???
HELP HELP HELP HELP HELP HELP HELP HELP HELP HELP !!!!!!!!!!!!!!!!!!!!!!

nitro guzzler

doesnt sound good.Try 4 1/2 turns out on the high speed needle and 2 1/2 out on the low speed.works everytime for me.let me know

jeremy sawatzky

thnx. but ive gotten the highspeed turned out 5 1/2 turns but it still runs really hot. I have had my smaxx for only 4 months i dought its an airleak.

nitro guzzler

might be time for a rebuild.

DaveG55

Check your compression. Using one finger (and only one finger) turn the flywheel. If you can turn the engine completely over with just one finger you need to replace the piston and sleeve. It's pretty easy to do and costs about $30 - $60 for the parts. If the compression is good, don't dismiss an air leak. If you did not take apart and seal the motor when it was new you COULD have developed a leak. Heck, one time I even developed an air leak around a carb that I HAD sealed.
Dave

ramer

My Feedback: (3)

how did you find that you had a leak around the carb. i'm thinking that i have a air leak around the back plate but i'm not sure. is there any way of checking?

tommythecat

My Feedback: (2)

Yes, run the engine while spraying wd-40 around where you think the leak is, if it is leaking significantly, it should rev up when you spray the WD-40. You can do the same thing with starting fluid (ether).

Your best bet is to just assume it is leaking and seal the common leak areas with High temp O2 sensor safe sealer (autoparts store). Just put a tiny bit around the backplate and around the case where the carb body inserts. I also had a leak on the high speed needle fitting once, so you may want to seal above and below the plastic nipple as well. Use the bare minimum ammount of sealant needed to cover the surfaces you want to seal.

Also, check to be sure you don't have a leak in the fuel tank or lines. Just remove the fuel line from the carb and the pipe. Plug one end and blow into the other. If it holds pressure, its good, if it leaks at all then you need to find the leak and seal it (usually around the fuel tank cap.

chogan

I agree - sounds like classic leak symptoms. You can use a little silicone on the carb base. Check the back plate - you can do the same thing there. Most likely it's the HSN seat/fuel nipple. Replace the seals, don't tighten too much.

jakjr

My Feedback: (18)

You didn't by chance change fuels did you?

Ive noticed the traxxas engines seem highly sensitive to fuel changes. The 2.5R in my T-maxx can go from running majorly rich/cold to majorly lean/hot just by changing brands of fuel (even if the nitro %age is the same). It seems to run the absolute best on 20% traxxas top fuel.

jsclimbn

any one know the stock carb setting for the trx 2.5. including the idle, low, and high speed.

pinky2252s

high speed 4 1/2 out low speed flush with the carb, the idle? did you mess with that at all? if you didnt theres no reason to adjust it

NitroNuisance

I Changed the idle! doesanyone know the factory setting for that?

DaveG55

1mm - 1.5mm air gap

Danju

i just changed the fuel in my 3.3 from topfuel to odonnel (same %) and this engine is really sensitive to fuel change.... from stock settings, my engine would go to 300 in like 3 min....it was so fustrating...just when i was about to give up, i richend my HSn about 1.5 turns. and the temps came down 90 degrees.... and now, im having a blast with it.....

unwritten7

Having same problem. 4mins and its up to 300+ just wondering if the original poster found the problem.

mik32526

hey yea about that im a new member and im having the exact same prob i think i really need a new sleeve and piston but i just bought it like two weeks ago i am a beginer in the whole nitro thing thankyou this advice has helped alot

camaro2666

i have a t-maxx 2.5 with a dual exhaust i made out of copper fittings,looks good sounds great but having trouble getting the tune up set just right. copper tubing is 1/2 tube

rooker

My Feedback: (1)

Seal your engine!!  I fought the same issues before I sealed it.  Believe DaveG55.  I have done things that he suggests, they work.  If those stock settings do not work(or close to stock), seal your engine and check pinch(compression)

silverman1

100% agreed, Hey Rooker hows things going!!!!

rooker

My Feedback: (1)

things are going good.  I ditched the Acme and got a Tmaxx with a 2.5r.  I also have an electric Rustler now.  Thanks for asking.  Haven't heard much out of you lately or I missed your name?

I have tried to pay attention to these posts to learn.  I think it is working!!

4x4Redneck17

Hey jeremy, im new here and im havin the EXACT same problem with my 2.5. However mine will not even idle.  I just had it rebuilt and i think the tuning is wayyy off or i might have a air leak. I turned it 4 turns out on the hsn and it sounds kinda splotchy. i turned the lsn out 2 and a half but no results. The only way to make it keep running is to give it gas with the controller. Then when i take off with and let off on it a little bit it cuts off. Any ideas, and is yours doin this too Jeremy?

chuckstattoos

you need to adjust your idle 4x4 just turn it clock wise a 1/4 turn at a time and check again you really want to adjust the idle while the truck is running so turn the throttl trim up enuf to keep it running then change idle and turn trim back down to 0 and see if it does it. and make sure when you are setting the needles to stock you are turning them out 4 turns not half turns if you go on youtube theres ton's and ton's of videos on this kinda stuff.