RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

i had the same problems with tuning and took the t-maxx motor off (with the advice of my hobby shop owner )and threw it in the trash.... and got a os-18. ... a perfect drop in for the t-maax ...and broke it in to the specs from os.. and have not had to tune it since. this engine is great...more power than the stock maxx and will wheelie on comand..the t-maxx engines are garbage. and are respectable hobby shop owner will/should tell you the same thing. the engine is a traxxas disaster...

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

Ranger and all,

I recently felt my flywheel and i can turn it with one finger easily. It over heated and got loud yesterday. Today i found that my exhaust manifold headir was broken. I still think my engine is done because My truck didnt get real loud until the last minute...my truck has been acting really weird for a week. My main question is can the RD Logics twin exhaust system be used with an os 18 tm? Also, if i can turn my flywheel easily, could that be from the broken exhaust...because a cant determine whether my engine was acting weird because of the broken exhaust or cuz the engine has lost it's compression. I think my engine is done because my engine has been giveng me problems for a while and i only heard my revo get loud at the last minute AFTER it overheated. I think the manifold got weak from it overheating but my engine is still blown.

If the RD Logics twin exhaust is compatible with revo i have nothing to lose by buying it. Let me explain: If the problem is with my exhaust...problem fixed. If the problem is from the engine, i get an os18 and i STILL have a great exhaust to use with my os

Also guys, if i can turn my flywheel, that just means that SOMETHING is wrong, not just my engine. Right?

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

If you can turn the engine over with one finger "easily" while it is cold than you are lacking in the compression department. It could be a loose cooling head, loose glow-plug, bad gasket under glowplug or under the cooling head, or your piston and sleeve are worn.

It's also possible although highly unlikely, that your flywheel is loose and you arenb't actually turning the crank over. Although if your flywheel was that loose the thing wouldn't have been moving at all.

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

Tommy,

There is still some resistence on the wheel its just that i can (without much effort) turn it all the way around. I can hear and feel the 2 strokes of the piston while i move it. I is definitly moving the piston.

Im about to order an os 18tm

What exhaust should i get with that?

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

Good luck with the TM, I love mine.

I know nothing about pipes for the revo.

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

See new thread about a revo setup with an OS 18 tm and what good compatible pipes there are. I just broke my stock exhaust manifold for the second time and i dont want to put another $20 into a poor exhaust system. Reply to this in the new thread named

"REVO w/ OS 18tm: Exhaust Systems"

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

Thank god it ain't just me!! My trx 2.5r was great through the break in, and aftrwards for a while. But then I let it sit for awhile with all fuel burned out, engine preped with afterrun oil etc.
I pulled the truck out and it would not pull fuel to carb. I rebuilt carb, new o-rings, set everything to traxxas specs etc. It ran good, but was temping about 260, i richen it up, but it would not hit 2nd. I burned that tank out and called it a evening. Did all post run prep, tried to run it again started ran for a little bit quit. Tried new glow plug nothing. I pulled the engine down checked the sleeve for pinch it got tight near the top. Put all new o-rings in new head gasket, sealed motor very lightly with silcon, and I mean very lightly. It would not pull fuel to carb when priming it with finger over exhaust. I hooked the fuel tank to my OS .18 in my tnx and cranked it, its also got simalar type of electric start as revo. I got fuel to carb imediately!!

I have never been so frustrated with tuning a engine in all my life. Now before all of you sling crap at me and call me an amature etc. I own 20 nitro's, engines such as ofna, thunder tiger, OS, gs.25 cen .16, machs. So you can say it is me, but i think the engine is crap. When i bought my first tmaxx. I fired the engine for the first time set to factory settings by traxxas, it shot up past 300 degrees. I shut it down imediately.

I have a new trx 2.5 I'll sell out of my Jato, honest I never starrted it or put nitro through it. I am afraid to try to break it in for fear of the same results, new engine for the JATO.

OH if your wondering the REVO got the RB concept 323tm with exhaust mufler and all for 219.00 shipped:D

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

When you rebuilt the carb, did you check it for obstructions. Did you blow some presurized air (PC cleaner works great) through the fuel path? I had similar issues and fought with them, trying everything, eventually I found some debris inside of the HSN fixture. Cleared it and all my problems were solved.

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

I agree with silverman, the trx could be better, I'm hearing too many bad reports on this engine. Mine never saw temps below 270. I rebuilt the carb, checked piston and sleeve and checked for air leaks and everything was fine. After about 1 & 3/4 gals it threw a fit and overheated to 410 which fried it [&o]. I can remember having a conversation witha traxxas engineer a while back and he told me that unlike some engine manufacturers (RB and OS are a couple he mentioned), traxxas don't bother with a secondary machining stage when making their engines. I am not an engineer, however, to me it sounds like traxxas are cutting a few corners here and this may be the reason why people are having so many problems with the TRX.

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

Obviosly there is something traxxas is doing wrong because i have several other nitro's as well and never experienced problems like I did with the 2.5, I spent more time tinkering with this that or something, tearing down rebuilding, checking for leaks, rebuilding carbs! It almost drove me out of the nitro hobby which i fear it did to some of the newbs who bought one. Maybe traxxas should stop being so greedy and outsource the engines. They would sell sooo many more with OS engines.

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

I second that! Traxxas need to listen more to their customers. Some people on here refered to the TRX as "junk" which I thought was a bit harsh. However after having considerable experience with the trx now, I feel it is the appropriate word to use- junk :D I have just bought an OS 18 TM.

Oh, and the traxxas E-Z start is also junk, my second unit failed on me today:eek:

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

There is an issue with the design of their ez-start, there is a dual power op-amp that gets blasted i assume by feedback from the ez-start motor i replaced a bunch of them they are like 5 bucks a chip, i havent really looked into why it fries them, but usually the glow plug side of the circuit fails. I do like how durable the owb is and how easy it is to use. I bought a sullivan tigerdrive and the owb failed after 2 runs [:@] dont know maybe i got a bad one.

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

That is a great idea. I wish they would atleast give you a choice when purchasing. Like buying a 1:1 car, you get a small selection of motors and decide what is best for you.

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

You may have to adjust how fast the car shifts into second gear. It sounds like the car may be shifting into second gear to early which would cause the car to lose power and bog. For your other problems I am not sure, it sounds like it may be the low speed needle not being set right. I had many problems with my jato's engine. I just finally took it in and they called up traxxas and got it tuned right. Then I had to do a little fine tuning myself. Maybe that is what you need to do.

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

I decided to add my 2 cents, I was so frustrated with the 2.5 in my tmaxx I was ready to throw it off a cliff. All the overheating probs, would not hold a tune, died all the time, I feel your pain!

On a better note just finished breakin on an OS18 for my maxx. WHeelie monster! ONe tuning question though? If the engine dies on deceleration after a speed run, is it running too rich or lean? or is it an idle problem. It happens 1-3 times a tank, but always fires right back up! Temp is running 210-240 degrees F

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

I Talked to a kid who has 9 gallons of 30% top fuel through his trx 2.5. I feel like a idiot! I can tune everything else I own but not these motors. The other thing even 2 years back i could not get a traxxas glow plug to save my life, even the big outfits like tower hobbies had them on back order, and guess what They still them on backorder. Ask a bunch of hobby shops what to run, and you get 10 different answers, 1 shop said os lc3, another shop said megatech, finally called traxxas and they said mccoy mc 59 or 9. I used pressured carb cleaner, and blew the carb out quickly before re-oringing everything.

Started to prep my rb tm323, and I launched a exhaust mainifold spring, man was i pissed at myself. I looked everywhere for it. When the new springs arrive it will magically appear.

I have Murthy on my side when i work on things ocaasionally or maybe its those gremlins.

I agree though with you guys, Id gladly except a few less 1\10ths of hp for reliabilty. For duratrax going to OS .18 motor and tamiya doing the same awesome!! I love OS reliability, and power, just awesome, has anyone shoehorned in a os .18 into a jato???:)

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

This might have already been discussed (I didnt read through the whole thread), but what fuel are you using?

The 2.5R is very sensitive to the fuel used in it. Try some Traxxas 20% top fuel and see how it runs, that is what I run mine and so far it is the only fuel I've found that it runs worth a darn on.

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

I run my maxx at about 290 to 300 degrees, never had a problem. This is where I get the best performance. I'm sure Traxxas recommends 270 degrees, that would give the most longevity out of the motor. Using O'donnell 20%. I have purposely tried to burn out this motor, so that I can install the OS 18. Seems to just get better with a little more heat.

RE: Traxxas Trx 2.5(r) Tuning Problems...Any advice
 

my 2.5r still had great compression after the 5 gallons I put through it, but it is just wayy to weak on the low end. I got an RB TM323 and was amazed at how well it held its tune. Most importantly the power this thing puts out is just phenominal.