• Welcome to RCTalk! 🚀

    Join the #1 RC community where hobbyists connect, share, and get expert advice on RC cars, trucks, boats, drones, and more!

    • ✓ Friendly & passionate RC enthusiasts
    • ✓ RC tips & troubleshooting
    • ✓ Buy, sell & trade RC gear
    • ✓ Share builds & upgrades

Problem keeping trx2.5r running in my revo

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
R

REVOlutionary

RCTalk Member
Messages
26
Reaction score
0
Points
0
RC Driving Style
ok this is the deal I'm trying to save up some money to get a new engine because I've been having some problems with my trx 2.5r. i've tried everything I've rtv just about every possible leaking area on the engine that is was told to, I've checked the compression on it and it has around 51psi cold. I've put a new carb on, made sure the glow plug was new and in good condition. ok now my problem, the truck was starting and idleing fine but as soon as you go to take off it dies. now I've checked the low speed screw and it was set correctly also the high speed screw was about 3 3/4 turns out and it would run about 215 like i was told to, next if i do get it to go and run it will run for a couple of minutes, get warmed up and then die once i let off the gas, and wouldnt start back up for a couple of minutes until it cools down. now it is to the point that it wont even stay running, i will put the ez start on and it will fire up but as soon as i let the button go it will die. but if i leave the button pushed in and the ez-start motor is spinning the engine the motor will run.(kinda crazy i know) I'm to the point were I'm just about to sell the whole thing and give up.
i live up in sacramento,ca up north, if anyone could help me out i would greatly appreciate it, even if you could just give me a couple of things to try. :help: :help:
 
Need more info. Are you all the way through the break in? How much have you run it since finishing the break in? (assuming you have finished)

Have you tried to lean it? What signs or symptoms does it make right before it quits?
 
How much fuel have you gone through. It almost sounds as though your p/s is shot. Check the compression warm if you can get it there, just don't burn yourself. When it's warmed up can you spin the flywheel easily by hand?
 
3 3/4 turns on the HSN? Weird... Mine has to be way richer than that to run right or it stalls. I have to run at least 1 full turn out from flush on the LSN and 5.5-6 turns on the HSN. I have about a gallon run through mine...
 
this happened on my Ultra LX Comp. Try taking the truck by something(bumper), holding it in the air and then give it a little gas, just over a little to get the wheels turning. Then put it on the ground and you're off. It worked for me, although it may not work for you. Please get back to us if it doesn't.
 
olds97_lss said:
3 3/4 turns on the HSN? Weird... Mine has to be way richer than that to run right or it stalls. I have to run at least 1 full turn out from flush on the LSN and 5.5-6 turns on the HSN. I have about a gallon run through mine...
Click to expand...
Factory is only 4 turns out on the HSN and flush on the LSN.
 
I'm with Olds on this one. My TRX was happiest at just about 6 turns on the HSN and flush to half a turn from flush on the LSN.

I wouldn't hold it up and get it running then go. You're not solving the problem, which is it stalling after it warms up. Besides, running a nitro with no load will ruin it if you do it over and over.

I'd set your needles back to factory, then back your HSN out 5 turns and give it a whirl.
 
Don't band aid it, it's not a viable solution. Sorry Spit but that ain't gonna work. If this is new, use wd-40 to check all possible areas for a fuel leak. Also what are you weather conditions like? Rainy, humid? Another, pull the plug and check to see if the whole coil glows or if it's just the inner (deepest) part.

Maybe something in this link will help ya:
http://www.rchobbies.org/cars_eng-tuning.htm
 
olds97_lss said:
Yeah... I know. But mine won't hardly run at those settings. It's way to lean on both needles.
Click to expand...

Just goes to show how much climate has an effect on these engines, mine ran rich on factory settings. My 2.5 is 3 1/4 on the hsn and a 1/4 in from flush on the lsn, it also doesn't run good at 215 degrees, it's happy around 245-250, it has just over 2 gallons on it.

So REVOlutionary did you buy it new or used and how much fuel has been run through it? Dieing out after running a few minutes is common during break in, but it's also common on an older engine that is loosing compression.
 
ok this is the deal the truck was bought practically new it was broken in and thats it. i personally have run about a gallon through it but about the last quart i ran through it it was acting up real bad. i took it to a shop and the guy tweaked on it and adjusted the needles and the LSN was about an 1/8 out from all the way in and the HSN was 3-3/4 out. now i know it sounds crazy the guy said the same thing he checked the cold psi and it was 51. he fired it up and it ran around 200-215. they guy told me it should run around that range but from what I've heard i thought 250 was about right for these engines.

when the truck runs for those few laps it does it will run and then when you let off the gas and then gun it again it just boggs but runs and you can drive it. but then it just dies and then wont start agin til it cools off. the weather aroud here is around 50- 60 degrees it wasn't humid or anything just windy.

SpitFireV12RR said:
this happened on my Ultra LX Comp. Try taking the truck by something(bumper), holding it in the air and then give it a little gas, just over a little to get the wheels turning. Then put it on the ground and you're off. It worked for me, although it may not work for you. Please get back to us if it doesn't.
Click to expand...


i can't get the truck to stay running anymore to even try that. and if i do as soon as i give it gas it dies. I've gotten it to the point that it will idle but as soon as you give it gas it immediately dies and if its warmed up then you have to wait a few minutes for it to cool down to get it to fire back up.

i did the whole pinch the fuel line thing like it says and count and at a 1/8 turn out from fully in on the LSN is where it shuts off at 3 to 4 seconds. thats what I've been going off of. the guy at the shop told me that i dont know if thats how to do it or not. and the HSN ran pretty good at 3-3/4 4 was to much the truck would run at 180-190.
 
1/8 turn from closed on LSN doesn't sound right. The stock LSN is the head of the screw should be flush with the housing. The temps the LHS is recommending are too low as well. 2.5 should run 230-250. 200-215, if it's running most likely won't even shift. Seems like your LHS might be leading you astray.

oops, my above post should have said air leak NOT fuel leak. Sorry about that.
 
Newbie's .02 here...

Have you replaced the fuel filter and or cleaned the air cleaner?


Sorry just came to mind and had to ask :)
 
Personally, it sounds to me like both needles are too lean. The reason it isn't starting back up after you've run it is because it's running too hot. The fuel actually boils away before it has a chance to combust, so it won't start. It's too hot because it's running too lean.

Again, my suggestion is to get the needles back to factory or a tad richer than factory. I'd also get a fresh glow plug, clean the air and fuel filters and consider replacing the fuel tubing. Run it until you get it good and warmed up, then start tuning it for performance. I would not, however, suggest you get it running while holding it up then dropping it on the ground. Putting load on the mill that suddenly may cause it to tear up the drivetrain or engine. The goal is to solve the initial problem, not create a stop-gap solution that will cause bigger problems long term. It's a process of patience, once that can become mind numbingly frustrating but will pay off huge if you stick with it!

Good luck!
 
Monkey Wrench said:
. I would not, however, suggest you get it running while holding it up then dropping it on the ground. Putting load on the mill that suddenly may cause it to tear up the drivetrain or engine. The goal is to solve the initial problem, not create a stop-gap solution that will cause bigger problems long term.
Click to expand...

I don't mean to let it run in the air and then drop it while its running...I meant to let it get used to turning the wheels in the air and then place it on the ground and go. Just wanted to clear that up, as I don't want to give bad help. Because when you do that, it clears up any unused fuel while idoling(because mine was bogging out). Just thought it was doing that, like mine.

I would listen to Monkey Wrench. Like he said, 1/8 of a turn to closed for the low speed sounds way too lean!

Try what he says, it should help, but if it doesn't give us a ring.
 
i do that and then the truck has no bottom end its gutless until it builds up the R's and then it takes off but if you let off the throttle it just boggs down and wont pick back up at all.
 
Have you ever taken that mill apart? I have no frame of reference, so I don't know if 51 PSI cold constitutes good compression or not. If I can turn the flywheel pretty easily with the plug in, I know my compression is starting to go.

Let me ask you, you say you've run a gallon through it, and up until this last quart, it ran well. What, if you know, were your needle settings? Did you ever treat the engine with after-run oil? Ever pull the mill off the truck and really scrub it down? How often did you clean and re-oil the air filter? I'm truly not questioning your care of your rig, just trying to get a history of the mill.
 
I think Monkey's on to it with the overheating issue. As I said, your LSN is just too lean, fatten it up. Call Traxxas and ask what compression is on a new 2.5 is. Also, you saying it bogs from the start until it builds up the rev's to go, check you slipper as well.
 
I'd have to agree with jet and monkey, it sounds lean. If its bogging then chances are its too lean. If it were too fat it would gurgle then stall.
 

RC Builds

Back
Top