Tuning your TRX Engine

[Double G]

Hope a mod sees this and will update the first post of this thread.

Good post and yes I did.

[blunts4m3]

The unfortunate part of this is, here is the only place where I can find the information I need to reset my carb etc etc, and that link on the first page, doesnt work, apparently again. Perhaps if I pm this Double G fella he will fix it again.

[cherokee77]

I bought the 2.5 T-Maxx from an attorney in the box, he said he drove it for a few mins and it died and did not want to start,so he shelved it, men I was really happy the thing was brand new ITB, anyways Itried to run the motor, and believe me i have been into these Nitro engines for a lots of years and own a performance shop, to make a long story short, I went out and bought the 3.3 and thought breaking it in by the books,I would have a good truck,I dont know if I got a bad motor cause the thing ran like crap out of the box..I live in So. Cal,weather similar to texas, why cant these motors be like our airplane motors, that runs every time,without all the break in crap, I was so frustrated and seen this guy driving a TA 4.6 MGT, and I bought it from him...thing starts and runs perfect, I'm not putting Traxxas down, as I bought an e-maxx and love it except I am a Engine noise type of guy..just my 2 cents about The 2.5 and 3.3, just too much to deal with and getting a bad rap, hopefully traxxas will come up with some kind of breaking in their engines so everybody could have a good time with their product...Tnx

You didn't follow break-in, and then you drove it in sub-zero temps (and I'm assuming made no provisions to keep heat in the motor since you didn't mention it). So to me, it looks like you're piston and sleeve wore out early, based upon your symptoms. I imagine you leaned it way out to get the temps up.

So then because you didn't follow directions, and wore your motor out early it's the fault of the motor?


No, most people don't abuse their equipment as you have. If you drained the oil from a Ford Taurus and then locked the motor up running it without oil, would it be the fault of Ford? No, of course not. You were the reason.

The same thing applies here, as it sounds like you starved the motor for oil. Then you complain as if it's not your fault...

gonna be exactly the same pretty much!! play with it and keep on playing(tuning) it

[Nitronaught]

I bought the 2.5 T-Maxx from an attorney in the box, he said he drove it for a few mins and it died and did not want to start,so he shelved it, men I was really happy the thing was brand new ITB, anyways Itried to run the motor, and believe me i have been into these Nitro engines for a lots of years and own a performance shop, to make a long story short, I went out and bought the 3.3 and thought breaking it in by the books,I would have a good truck,I dont know if I got a bad motor cause the thing ran like crap out of the box..I live in So. Cal,weather similar to texas, why cant these motors be like our airplane motors, that runs every time,without all the break in crap, I was so frustrated and seen this guy driving a TA 4.6 MGT, and I bought it from him...thing starts and runs perfect, I'm not putting Traxxas down, as I bought an e-maxx and love it except I am a Engine noise type of guy..just my 2 cents about The 2.5 and 3.3, just too much to deal with and getting a bad rap, hopefully traxxas will come up with some kind of breaking in their engines so everybody could have a good time with their product...Tnx
gonna be exactly the same pretty much!! play with it and keep on playing(tuning) it

You can't compare a large block Nitro airplane engine to a land vehicle Nitro engine. They are not designed for the same things... For one thing thei discplacement makes them much more forgiving on needle settings, so is the amount of toque required... Airplanes require HP more than torque and land vehicles require more torque then HP... So they are going to run and tune differently........ Simple.

I own 3 TRX engines. my first engine was the TRX 2.5, I was new to nitro , didn't know how to tune, but I followed the instructions had my learning curve and it went 4 gallons. I rebuilt it with a new piston and sleeve, even added the 2.5r cooling head and it went 8 gallons before it starting losing perfomance but I still ran it for another 4 gallons to see if it would finally die,,, it would still run but needed a new piston sleeve and front bearing... It's shelved for now...
Engine 2 is a 3.3. Went 7-8 gallons and I just rebuilt that one and broke it in... HAs about 1/3 of a gallon through it and it's starting to wake up.....
Engine #3 is on it's 5th gallon and running fine...

I race at a track with a bunch of Traxxas RC's (mainly short course trucks now)... I've rebuilt engines for others at the track and helped some of the newbies.... Lost count after 20 odd of them... They get ran every weekend at the track with quite bit of run time on them and the only times I see issues there is physical evidence that it was ran too lean or too rich... Now the causes of those mixtures to be off can range from a leak, to just poor tuning....

Just my experience with these engines....

That previous owner could have already damaged the engine prior to you touching it... Just by running it without breaking it in could have stressed the internals enough for them to fail no matter how you may have treated it....

I find your post not exactly very fair to Traxxas since you have no clue what the previous owner did... 30,000 rpms without being broken in would do the trick perfectly...

Your quote of Misbehavin' seems in respons to something he had seen, like in a picture... And if that previous owner ran his RC without tuning he would be correct in his observation, but I think you forgot to include that tidbit of information in your post....

This thread was designed to help people with tuning, not to complain of a bad experince you had buying a used Nitro RC.

[Jwayne15]

Im still having problems tuning my trx runs good but no where near as snappy as the ones ive seen thats been tuned in I cant figure out where im going wrong tuning it

Its not peppy until its rolling already you if I qtr throttle it it kinda sputs but if I nail it itl kick in I just put new clutch and and fly wheel on idk if I have the idle pin set wrong or my lsn isn't set right would like to run it more in the process of try to tune it I cracked my bulkhead (rear)

[12TRAPTOR]

I have a 3.3 but I can't seem to keep it idling. I have tried everything but nothing has worked. Can anyone help?

[slidin6ofem]

I have a 3.3 but I can't seem to keep it idling. I have tried everything but nothing has worked. Can anyone help?

Does it start? How long does it run until it dies? New rig or new to you? I had a real tough time tuning mine until 1. it was broken in plenty and 2. was all warmed up.

[Spentdrop51]

My 3.3( running of of 33% nitro) will not seen to tune in right, it won't start. Nor stay running. Please help.
Thank you in advance.☺

[PUDDNMONKEY]

Reset to factory tune of 4 turns HSN, 1n3/4 LSN and idle gap of 1.0mm. Fresh plug too, see how that does for u. Hope this helps.

[Mrsickaluffigus]

Ok so this is a long thread to try and sort out this problem on a phone but i just got a slayer pro i broke in the 3.3 running 33% but even with the hsn at 5+ turns and the lsn around .5 to .75 turns out from factory it seems to be detenating i have black plugs with the coil almost always protruding from the plug now i have plenty of rich blue smoke and its quite responsive but stalls after a long run but if ran in short burts it will stay runnin till i blow a plug and it has just under a gallon of gas thru it
any help would be awsome thx

[Double G]

Ok so this is a long thread to try and sort out this problem on a phone but i just got a slayer pro i broke in the 3.3 running 33% but even with the hsn at 5+ turns and the lsn around .5 to .75 turns out from factory it seems to be detenating i have black plugs with the coil almost always protruding from the plug now i have plenty of rich blue smoke and its quite responsive but stalls after a long run but if ran in short burts it will stay runnin till i blow a plug and it has just under a gallon of gas thru it
any help would be awsome thx

Your HSN is too rich and trying to compensate for a too lean LSN so you may have smoke up high but trouble with idle and high temps down low. Go back to factory LSN setting of 1.75 and an idle gap of 0.7-1.0mm open and HSN at 4. Typically the HSN will need to be leaned a little and the LSN needs to be a touch rich from factory.

[Mrsickaluffigus]

Even runnin 33% i thought i was suppost to run it rich with a higher nitro content

[Double G]

Even runnin 33% i thought i was suppost to run it rich with a higher nitro content

Again :

Your HSN is too rich and trying to compensate for a too lean LSN

[Nitronaught]

Even runnin 33% i thought i was suppost to run it rich with a higher nitro content

I recommend reading this https://traxxas.com/forums/showthrea...ul-Tuning-tips

Yes i posted earlier in this old and long thread, but it's very obvious you have not gone over it or your questions/statements would be different.

[Dura36]

Its too hot richen high speed needle should run 160 to 190 no hotter if u dont see blue smoke its to lean

[Double G]

That is too cold. Should run low to mid 200's.

[Dura36]

3.3 in rustler all broke in clocked today at 91 mph superfast scarry at 91

[Nitronaught]

Its too hot richen high speed needle should run 160 to 190 no hotter if u dont see blue smoke its to lean

At 160-190 degrees your internals are not fully expanded and you are putting a lot of undue stress on your conrod and piston...

Where and how are you measruing those temps.... No way are you hitting hose speeds... Your conrod is swimming in fuel inside the casing at those speeds you are reporting and surely this i swhen the conrod get's stretched and or splits from the stress.

Mfr recommended running tems AT THE GLOW PLUG should be between 210-260 no more than 270 and no lower than 200.....


91 mph with a poorly tuned 3.3 (160-190 it's not tuned right)

Obviously you did NOT read the link I provided.

[gfdiers]

Honestly in all my 25 plus years in the RC business and hobby that Traxxas makes some of the three best nitro engines I've dealt with, with some negatives but over all the best. For beginners they can be difficult to tune at first but you'll get the hang of it. This one thing I must say with emphasise is it's very important you follow your break in procedure the way traxxas wants you to do it. Then follow the tunning procedure to fine tune your engine. Keep in mind you will have to re tune your engine frequently and for some ppl I see that's where problems start. Not keeping track of your needle turns getting confused with where your settings are at, always remember how to return your engine to factory settings and start over before you call them or taking it down to your hobby shop. Allot of times ppl bring in their nitro models and say it won't stay running. And majority of time I find it's horribly out of tune and this is with Traxxas and other makes. Secondly is maintenance, clean your TRX engine properly after your done with just follow the procedure very easy. Neglect and abuse will shorten your engine life, I have engines that are many years old and still get good use out of them whether I'm at the track or just bashing around the yard. I will admit they can be touchy and sensitive that's usually when outside temperatures start to fall and it takes patients to re tune it. Invest in a digital temperature gauge and keep track of your temperature. At the track I like leaner and cooler (lean as possible without going over 270 Degrees) At home in the yard I like a little richer and mid 200's. Listen to your engine as well listen for cracking and popping noises after you been bashing for a while you may need to richen it.

[Renegademarc]

I printed and read this article seven or eight times, I have alot of punch for about the first five minutes of running and then my engine stalls. I performed all the recomended tests on the low and high speed settings, I am running at about 250 farenheight but I can only get five minutes or less before it stalls. I also added 15 inches to my pressure line because it seems to be loading up. This did reduce the pressure in the tank and it doesnt bog anymore but I cant seem to fix the stall. Does any one have any suggestions or treatments that I could try? , I traded a thunder quake 1/8 scale for my t-maxx and I dont regret any part of ot, PLEASE HELP to get my 2.5 to stay running, I'm starting to get frustrated

niro passion to the end.

Due to expansion rate due to heat you lose the compression I have 5 1.5 that are all wore out and need to be rebuilt because of its stalling after 5 minutes or a quarter of a tank of fuel ran through it it's quick for the first 5 minutes runs like a top then it stalls and you can't start it no more

[dado099]

Hello,
someone can be so kind to measure for me the interaxial distances of TRX 3.3 engine backplate screws ?
Should be square ?
Thank you very much !!!

[RickG]

In a quart of nitro, whatever your percentage choice is, add 2 ounces of regular gasoline and mix thoroughly. The gasoline has a lower flashpoint and the engine will start better and idle a little higher. Change the fuel filter often. The small inline filters are just a fine wire mesh and tiny contaminants can get through. I take hole punch and cut a small piece of coffee filter to put inside. I hope that helps.