synthetic003

hey guys i recently bought the trx 2.5r i had the 2.5 but blew it up anyway i broke in the motor perfectly an i mean perfectly well i broke it in with 20% nitro then ran what i had left no big deal
well i know it isnt the smarterst move but i went from 20% to 25% and i was trying to run it in the grass but it just wanted to bog down an die but it runs just fine on the black top??? anyone got any ideas ? i never ran it in the grass till i switched fuels so i dont know if its that or if it is my gear box i removed the spur gear a while backwhen i was repainting an cleaning everything so i aint to sure how far to have the spur gear tightened please some one help an i know the 2.5r is not the best engine but i aint willing to go buy another this one is just fine for me so dont suggest i go buy another please

89ram

changing fuels only means re-tuning for that fuel. if it bogs down, your slipper certainly is not too loose. do you have a different fuel you could try? what gears do you run? do you have them for top-end? maybe you need lower gears?

bennyblanco

when it bogs do you see a lot of smoke cause if thats the case its to rich.

125cchyperman

If he's running in the grass then the grass will catch the exhaust and not allow it to disapate as fast as if driving on the pavement so it's going to look like there is going to be a lot more exhaust then there actually is. Or if the truck is actually rich and you just cant tell it onroad. Or maybe it's stuck in 2nd gear. When doing a high speed pass onjroad can you hear it shift into 2nd or dont you. This could make this happen.

There are several thing that could make this happen as when diving offroad you have a lot more resistance to the truck then if driving onroad. If you have any other questions just get back.

rawkfist2

OK we wil settle this now.

Onroad, engine spins freely with little resistance and air gets sucked straight to the engine


Offroad, engine spins with high RPMs and is hard to move. Air is getting restricted by the grass in front of the car. Meaning, engine will become hotter. Every time you go from onroad ot offroad, tuning must be changed unless the grass is about an inch high. Thats y i like to drive on the golf coarse! Dont tell those cops... Hope this helps.

125cchyperman

AHH WHAT ARE YOU TALKING ABOUT. For one thing it could be many different things that is causing this. You air theory has absolutely nothing to do with this and to tell you the truth it make's absolutely no sence at all. It trully doesnt make any sence.

The reason why most will see higher temp's in there engine or see there engine bog (if the engine is not tuned right or the gearing is off) is because of the grass. The grass gives a ton of resistance if high enough and the truck has a tough time moving. The reason why you see the higher rpm's is because the truck will not shift into 2nd and will stay in first gear. If it does shift into 2nd it will then bog down and will shift back into first. Once again if the grass is high enough and gives more resistance.

The tuning does not have to change at all when going from onroad to offroad. I do not know where you got this or if you thoughy this up by yourself, but you dont have to retune.

Tuning your engine is just getting the right fuel to air ratio to your engine to make max hp. If your engine is already tuned correctly then you should be alright. And most dont run there neeldes so close to being go or blow so you dont need to retune. I have no idea where you came up with this stuff but your off.

rawkfist2

I NO read my post. It will over heat. just do this. go out in the road and tune it. Then go in tall grass and tell me if it is tuned perfectly. It always needs a little richer when running in grass!

Pritchett

you don't tune to temperature, you tune to performance.

Engine runs hotter in grass due to greater resistance. If anything should be adjusted, it's the shift point.

There's no reason to retune your engine everytime you cross the road.

MBX5T Maniac

My Feedback: (-1)

It could also be a clutch problem, because there is less strain on the clutch onroad, vs offroad, which is a lot more.

But when you switch to a different % of nitro, you must break you engine in again.

rawkfist2

I jsut went and used my truck WOT on grass. 248 temp. WOT on street. Temp 216. No one can say that temp doesnt matter

MBX5T Maniac

My Feedback: (-1)

It's hotter, because there is more strain on the engine. The engine revvs more offroad, because there is less traction, and the tires are spinning, and fighting to get some traction. Therefore the engine temps are hotter. It's common sense. And the engine has to rev more in order for the truck to be able to fight it's way through the grass

rawkfist2

Exactly what im saying. People say tune for performence. How can you say that. The temps will eat ur engine alive.

MBX5T Maniac

My Feedback: (-1)

Not if you have them below 270*. If you keep them at that temp, you aren't straining the engine, because the temps would be much higher. Just make it a bit richer than normal when going through grass, and stuff, that way you aren't going to ruin your engine!

ScRacing

You guys have also missed on how much traction you have in the grass, messing around in grass is about hte best way to eat a diff, to add to the strain, when you are drifing in grass you arn't going in strait lines, you are probubly bashing wich will also raise the temps cause you will be on the gas more, you will accelorate more, and there WILL be less air for cooling. Over all expect higher temps and that may mean a 1/16th turn on the lsn and hsn, not a biggey.

LowNoma

WOW! I have never seen so much whiny CRAP since I was in grade school. The man has a question. Can we get him an answer instead of arguing about temps?!?! Mine does the same thing and I would also like to know what is going on. I, however, used 20% all the time and it does it.

les_222

Does it bog down from a dead start or from first to second?

mrjerryk

You DON'T have to break in you engine again. You need to retune it but that's it. Why would you need to break in engine in again. It's already gone through the process. It's like saying you run 89 grade gas in your car when you first buy it and you break the engine in per the manual by not driving over 55 for the first 500 miles. But then 30,000 miles later you decide to run 93 grade gas and think your cars engine is not broken in again so you go back to the 55 mile an hour speed limit.

Once you engine is broken in all you need to do from that point is tune it no matter what % fuel you are running.

ScRacing

Well then traxxas disagrees wiht you, because htey say you should at the verry least take it easy for a few tanks.

aznherb36

at MOST you just need to run richer for one tank. and if its a nicer engine it may require shimming

rawkfist2

Traxxas also sold me a crapmaxx.....

89ram

trx likely wants you to take it easy after you retune for different fuel so that you take your time and get it right, rather than burning it up right away. richen up for grass? whatever!

125cchyperman

Just because traxxas said to do it doesnt mean that it's set in stone. Rawkfist you will see higher temps when running in the grass, I mean thats a no brainer. But you do tune for performance and not smoke or temps. I mean come on, we all have been saying this for so long, there's no point in arguing that.

This hole thing got out of hand by rawkfist saying that "Air is getting restricted by the grass in front of the car". This makes absolutely no sence at all in any way. This is how it got all out of hand.

You do not have to re break in your engine if you switch fuels. You should retune to see how the fuel reacts and your enigne reacts to the fuel. Because of different nitro contents, and oil and things like that. This is recommend but not a must. I dont even think some of you know what breaking in the engine really means. Once you have broke in an engine you can not break it in again the same piston/sleeve set. If you get a new set then you can and should but once a piston/sleeve set is broken in there broke in and if you try and break it in again your just waisting your time.

As I said before this all got out of hand when a person said that the cause of his bogging down was from "Air getting restricted by the grass in the front of the car". I rest my case

ScRacing

Im sure that is exactly it, and i do not mean rebrake in the engine, i mean take it easy, as in check temps all the time and check for any problems regurally for a couple tanks, maybe for the first tank don't go full throttle for more then 3-5 seconds, ETC, but if you have an extra glow plugs, a shim or two and a temp gun, then you shouldn't have anny problems tuning anytime what so ever for anything.

And becasue of the grass causeing you to go slow, you are not going to be doing 40 mph acrost your lawn like you cna in the street, wich would contribute to over heating.

Things causeing over heating in grass

To much rolling resistence
bashing in grass so you are on and off the throttle
driving hard
moving slow so there is less cooling for the engine
added strain to the drive train
requireing alot more torque to move at a slow speed than at any speed on pavement

bennyblanco

im going to ask the question nobody asked how tall is your grass? cause i drive my revo and savage in my back yard with no problem but we cut the grass twice a week if my truck boggs down in the grass is because is to rich but thats my truck!!

PapiLou

I agree. Both my Tmaxx and Revo run fine going from pavement over the curb into grassy hills or dirt and whatever else. Bogging down from idle sounds like it might be rich, I know the 3.3 in my Revo has a very fine "optimal" zone on the hsn and lsn. I usually try to go a little rich from that point just to prevent from having to buy engines all the time. On the other hand the 3.3 in my Tmaxx is really easy to tune and i usually run rich and it still has plenty of power, even for wheelies going downhill.

One thing I would also check or listen for is a sort of grinding noise coming from the tranny when in the grass. I had a problem once with my forward gear that caused it to lose torque if i got on the throttle a little too aggressively.