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-   -   Traxxas Trx 2.5(r) Tuning Problems...Any advice (https://www.rcuniverse.com/forum/traxxas-monster-truck-forum-251/3418197-traxxas-trx-2-5-r-tuning-problems-any-advice.html)

razor116 10-03-2005 02:44 PM

Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
I have had my Traxxas revo for about 10 months now. I have had amny many problems tuning that damn engine they put in it. The engine seems to give symptoms of too lean but there is always blue smoke coming out the exhaust. When i run it in grass it slowly loses its power until finally it just makes a long, drawn out, moaning sound. Is that from it being too lean or too rich. I think i was told that is because it is overheating which means too lean. But i have the high speed needle really far out. Also, could the low speed needle cause it to eventually lose power?

My most recent problem is that when i give it full throtle, it accelerates flawlessly through first gear. But after it shifts, the engine stutters and cuts out/ loses its power.

Yes, i have watched traxxas's dvd...i know it says i am running too lean but i really don't think that i am. I mean, when it happens, there is a nice trail of blue smoke. Could this problem be from it running too rich? I think it might because richening the highspeed doesn't seem to help any. Also, could the problem be from a blow, or weak glow plug? Should i be using a certain brand of glow plug or a certain degrees rating?

Please, i need all the help i can get.

Porsche968 10-03-2005 03:17 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Sounds like you have been having some problems with the TRX. I had lots of problems with that engine as well. My advice to you is to check your fuel lines for any breaks in them. It's probably best to just buy some new line it's cheep like 99 cents a foot. I would recomend opening the carb up and checking for worm gaskets since your that far you mine as well open the whole engine up and check for damage and poor gaskets. You should also buy a temperature gun. The little finger held Blue Duratrax infared temp gun works great for me. It sounds to me like theres something else going on besides bad tuning. Once you tear everything down reset all the needles to their factory positions and start again. You should also when breaking in an engine move the pistion to BDC between tanks. The DVD doesn't say to do this but, I feel it's an important step.

razor116 10-03-2005 03:53 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
I have brand new fuel lines in it right now. I need to know a couple of things:

1. Could the low-speed needle adjustment affect what the engine does with wide open throttle?
2. Could the idle speed adjustment have anything at all to do with my problems?
3. If i changed the fuel brand but not the nitro % could that cause weird **** to happen?
4. Are there any glow plugs that if i put in my revo would cause anything like this?
5. What are the factory settings of the needles...for example,

Idle speed: all the way in, then back out __turns.
High speed: all the way in, then back out __turns.
Low speed: all the way in, then back out __turns.

Also, i've been reading other threads and when people have tuning problems, the person giving advice always says check for leaks in tank, fuel lines, carb and so on. How could this cause my problems?


Try and answer as many of the numbered q's as you can, thanx a bunch
oh, one last thing, when my engine dies, should i buy a new truck or just get a different engine for it, i've her the os 18 works well with revo.

cat627f 10-03-2005 03:55 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
I had the same problems with mine, only to find out I had a air leak. First time was my fuel tank had a crack in it, then I fried the engine to find out that the hs neidle was stripped out inside the carb, so I junked the trx and bought the os 18 tm. Big differens, this engine tuns very easy and holds its tune.

razor116 10-03-2005 04:26 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Cat...i have alot to tell you...i just ran it and there was some wierd stuff going on....would you mind if we continued this discussion over the phone, that is if you are comfortable giving out your phone number.
thanx

Deandome 10-03-2005 04:44 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Dunno if this is a posibility, but I had a weird tune yesterday w/my Ofna/Picco .21 drop-in....

It started great, didnt' cut out, but it sounded & acted WEAK...it barely moved the truck. I leaned it out like THREE TURNS & got a little more power, but then I noticed one of my zip ties on the header/pipe coupler had come off. Seems that air leaks AFTER the engine are as bad as those before (carb) and/or in the engine (backplate/head).

I replaced it & all was fine...after I took 10 minutes to find the tune that I originally had & hadn't needed to change once ALL SUMMER!!! I LOVE the fuss-free nature of this engine, it's amazing!! I hope to god that I can get sleeves/pistons/parts for years to come, unlike the nightmare all you Fantom .18 owners are now facing.

Dean

flatout-> 10-04-2005 05:22 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Razor, you say you have the HSN "really far out". You may have it unscrewed past the O ring seal, which would create the same effect as an air leak (sucking more air than it should be, thus leaning the fuel/air mixture out) which could be causing your engine to overheat. Reset your HSN to 4 turns out and try it from there.

firemanmatt 10-04-2005 10:19 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Stock settings for the 2.5 motor is as follows:

HSN-4 turns out from closed.
LSN-1 1/2 turns out from closed (should be flush with the ring DIRECTLY surrounding the LSN.)
Idle should be 1mm out.

I have had similar problems. I see a TON of blue smoke coming out of it, and then I bring it up to me and check the temp, and Im running over 270 degrees. I cut a 2 inch round hole in the windshield to get more air moving towards the head, and it still doesnt want to fully stay cool when I run it hard. I'm thinking of cutting two 1/2 inch holes in the grill as well to get even more air moving towards that head. My wife's cousin has a T-Maxx that has the 2.5 motor in it. He put a larger aftermarket cooling head on his motor and said it helped alot. I actually like the looks of the stock head more though, and need to get over it personally, or I will blow this motor. However, for $100, Traxxas will send me a new one, so maybe blowing this one up wouldnt be such a bad thing so I can start over and REALLY get my new motor broken in properly now that I know what Im doing a little better!

Good luck, be patient, and ask you local hobby store for help if nothing else works!

DoubleC 10-04-2005 10:43 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
I am having the same problems as many of you are: overheating. I actually called Traxxas and talked to a tech. They dont tune to temp. Traxxas tunes for performance. I told the tech all my woes and he said that unless the motor is cutting out these little 2.5s tend to run hot. If you have lots of smoke then my advice: drive it like you stole it.

Dice it anyway you want, these little motors (quoted from Traxxas tech) will only last around 2 to 3 gallons. Thats about 80 to 120 tanks. Not bad imo. So, if your having fun dont worry so much. The motor is gunna blow sooner or later anyway. IF all you do is worry about engine temp than your doing just that: only worring about engine temp. Gotta just have fun with it I guess ;)

razor116 10-06-2005 11:44 AM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Thanx all you guys,
I just have one more problem: I have ran about 2 and a half gallons through and when i close the engine cut-off switch, the engine shuts off in less than a second! I have tried richening the low-speed needle and just nothin happens. it still cuts off in that same time. Do you guys think my motor is blown. And, if it is, should i drop in an OS 18, or should i just buy a new truck.

Thanks for all your responses...Just keep them coming.

flatout-> 10-06-2005 12:05 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Dump the TRX and buy an OS 18TM. It has more power, is more reliable and holds its tune well from what I have read. Cant wait for mine to come [>:] The TRX still has a few bugs IMO :eek:

razor116 10-06-2005 12:09 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
I know i should...i really want to....im only 14 years old and ive got to find out if my engine is Dead or not. If its dead should i junk the revo and go with something else or just drop in an os 18? I think i should get the OS but its expensive and i cant just spend $200+ when i dont have to....Spurface, look, i will get the OS 18 if the trx is dead but if it isnt i think i should justy get it fixed. Thanx...but from my problems that i listed do u think my engine is dead....i truley hope it is.

flatout-> 10-06-2005 01:17 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Lol, if your engine is overheating quickly regardless of needle settings, then in all probability, it's cooked[:o] Just ensure that you have no air leaks. And try running a lower nitro % content, this may bring down your temps. Don't flog your Revo, this is the next best truck to the LST (which many people say the LST is THE truck!) Stick with it. After I have installed my OS 18 I'm sure I will never look back:D Don't let machinery beat you!

TOCCHET_92 10-06-2005 01:41 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
i've had very few issues with my 2.5 and it runs fine temps only around 220, the expentant life is only 2 to 3 gallons,i'm going on 7 gallons and see no end in sight.:D

stilllost 10-06-2005 01:48 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Doublec hit it on the money he called traxxas and they told him what alot of us veterans have been preaching about the trx 2.5r runz hot. i like my 2.5r it keeps up w/ the savage and in most case rolls on by. if yer gonna dump $200+ on a engine might as well do it right and get the RB TM323. it comes w/ everything you need. os.18tm from what i here doesn't wake up until you get the trinity pipe/header combo.

My most recent problem is that when i give it full throtle, it accelerates flawlessly through first gear. But after it shifts, the engine stutters and cuts out/ loses its power.
sounds way too lean to mean. try getting the lsn to factory settings and leave it. then work that hsn till its on. my trx will hold a tune all day. when its start to get cooler i just lean it out a bit and there we go

cat627f 10-06-2005 01:57 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Don't give up on your Revo, this is a awsome truck and has a lot of potental. I personaly didn't care for the trx 2.5r one bit but $230 for a kick ass os engine to $500 for a new truck????????? Comeon now think !!!!! You wont regret the os, or a rb. This hobby takes some money to play but in the end you can't beat the fun.

razor116 10-06-2005 02:22 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Thanx cat, But how can i check to see if i have an air leak? I mean... I have only ran about 2 and a third gallons through it. It seemes a little early for the engine to be cooked.

And to the guy who thinks im running too lean,
If you had read what i said after that you would find that no matter how much i richen it, it does that. Sometimes it wont even accelerate it will just get choked.

Cat, can we speak over the phone?...its a lot easier

stilllost 10-06-2005 03:02 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
hmmmmmmmmmm yep i think its lean try pulling the hsn assembly off and clean it i bet its dirty. just hit me after i came back to see the progress.

razor116 10-06-2005 05:03 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Lately i've been on the phone with everybody:

The local hobby shop, you guys, Traxxas, some of my buddies... I've came to the conclusion that my engine is shot. It would be $70 for a new piston and sleeve, not to mention a shi*t-load of labor. Im not pouring in another $70 into traxxas's crappy engine. It's hard to tune, doesn't keep it's tune and lacks low-end power. Does anybody know of any engines that i should put in my revo? As of now, from what i read, im gunna drop in an O.S. .18tm, It's mad-easy to tune, holds it's tune, and has enough low-end power to pop a wheelie at 20 miles per hour. The other one i've been thinking about is the Picco .21, my localhb says that that engine is a ***** to tune and a newb like me would never get it right. Tomorrow im ordering the os 18 unless one of you guys gives me a better idea...


flatout-> 10-06-2005 05:16 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Razor, did u actually read my post :eek:?

razor116 10-06-2005 05:25 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Yeah, i did,

Im going to buy the os 18...i was just wondering if anyone knew of anything else? The only thing is, it's expensive...$220

flatout-> 10-06-2005 05:37 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
This may help u make your decision..

http://www.rcuniverse.com/magazine/a...article_id=549

michelob78 10-06-2005 08:17 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
The TRX makes a nice paperweight! seriously though they are among the most aggravating engine I have owned. I race and bash and when i do i see people with TRX engines killing starter packs to get em running my OS doesnt act like that. They do run like a scolded dog when everything is perfect but they will also make you throw your truck off a bridge from aggravation! I was sick of looking for airleaks breaking the carb losing its tune from day to day by more than i expected. There is life after the 2.5 and it is GOOD!

razor116 10-06-2005 08:24 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Hey, i just have a couple qestions. One, is the RD logics twin exhaust system for revo compatible with the OS 18?

Also, what is with the manual for the os 18tm?
i downloaded it and they make everything so confusing. They make up brand new names for highspeed and low-speed needles...and there are two low or mid speed needles, one highspeed, and an idle, how does that work?

firemanmatt 10-06-2005 09:59 PM

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 
Another thing to remember razor is that Traxxas will send you a new 2.5 motor for your old motor and $100. Maybe you just didnt break in the motor correctly. Maybe the motor had problems during assembly at the plant that made it. Who knows. The bottom line is, some people have had ZERO problems with their 2.5, others have had problems from the first time they started it. These motors are EXTREMELY small, running at EXTREMELY high RPMs, and run on a two stroke technology. The top of the cylinder actually has to "expand" slightly before it can run correctly. Maybe that was damaged and you aren't getting the correct compression for some reason.

Whatever happens, dont give up on the truck. The REVO is technology like no other truck. The after-market motors are a great idea in alot of cases, but be patient with what you have. If patience is somthing you dont have, you should probably look at an E-Maxx instead of a Nitro truck, because these things take ALOT of work. The question is: Is it worth it to you? Personally, I love working on my truck as much as I love driving it around.


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