new engine for my max

[jim]

I'm down right fed up with that trx 2.5 engine, it won't hold a tune for two tanks. it is extremely hard for me to tune

i have a few questions. (by the way, this is my first nitro)
1: its been only about 35-40 degrees out lately, that warmer it gets will it be easier to tune?

2:i can't seem to get that "sweet spot" were it will do wheelies on demand, i can actually get the high speed just right that isn't too bad. Its mainly the LSN that I'm haven trouble with, its in farther that flush with the throttle body is this normal?

3:how much will a 75cc fuel tank help with keeping a steady from a full to a low tank?

4: i might replace the engine soon with somthing else, i will for shure just get a new one when i need to replace the sleeve and piston in this one. so what do you guys reccomend for a reasonable priced (under $160) engine that has great tunability and newbie friendliness. Thanks a lot

EDIT: its was running at about 200, so i wrapped the head and it runs at a steady 260 to 290 degrees now (seems to run a bit better when warm

 

[SkyMaxx]

1. The warmer it gets the more reliable your indications will be. When it is cold out, the engine has better cooling characteristics. You might actually be at the sweet spot with a 170 temp check. Problem is that the outside air rapidly cools the engine for you.

2. Wheelies have a lot to do with engine power, but in most cases they have more to do with gearing and suspension set-up. If you have a top speed type gearing on the T, you will have a hard time ripping those cool looking wheelies on demand. Tell us what you are running in the way of gearing and suspension set up, and we can perhaps give you some changes to make (if they are necessary).

3. The smaller fuel tank might help, but it will reduce your run time. A trick I use when tuning my T it to tune it at a half tank of fuel. This way it will be a tad rich at full tank, right on at a half tank, and a tad lean near the empty mark.

4. For the price listed, try a Fantom or an OS. Both make solid mills that can hold a tune. I dumped my TRX Pro .15 prior to putting a gallon through it and got a Fantom. It is a great investment, powerful, and easily tuned.

Note: Be careful on the wrapping of the engine. You may actually overheat your engine and contribute to a shorter life (not a factor if you are getting a new mill). Engines run cooler in the cold; that is just the laws of physics at work. Wrapping it to keep it warm for start up is a good plan, but wrapping it while running...I would recommend against that.

 

[Skyline Racer]

Hey man, Same here, If you want to keep the 2.5 you can always get the Sirio replacement piston and sleeve kit for it. Or you can go out and by a O.S Carb for it " I AM NOT SURE IF the O.S carb will fit the maxx 2.5" because the carb is a 1/8 scale size. Correct me if I'm wrong. Later

 

[SkyMaxx]

The Sirio upgrade is a great idea. As for the OS carb, you just need to get the right one for the 2.5. I do not know which one is a direct fit, but there are members of this site that use OS carbs on their TRAXXAS POS engines.

 

[Skyline Racer]

Yeah its a great bang for the buck , 80.00 vs. about 200.00 when you can have the same power basically.

 

[sbb4us]

Jim, How much fuel do you have through your 2.5? Because mine was hard to tune and wouldn't hold a tune and wouldn't do wheelies for about the first half gallon or so, then all of a sudden I could do wheelies and it was easy to tune after that first half gallon. As you drive it the engine gets more power and becomes easier to tune (In my opinion).

 

[STYLEZ-MAXX]

Have you guys ever thought about the new Picco .21 Smallblocks? You want wheelies on demand? Well, here it is. You can check it out at OFna's website. WERKS Factory has one also called the P2, basically the same engine since its made by Picco as well. Really good upgrade with alot of Torque.

Traction plays a big part as well if you wanna wheelie freely. :ahem: . Try running your needles slightly richer since the weather their is Cold/Cool.

First post. Wooot!

 

[jim]

My gearing is exactly stock, i have done absolutly nothin to it
bnut today, i took a full fuel bottle full of fuel and i tryed to restart from stock settings and it just stunk. its about 45-47 degrees out today. i could get the high speed set no prob. but i could not get ANY ACCELERATION OUT OF THE LOW END!!!!!!! i started really rich at stock settings, then i kept leaning 1/8 turn it got slightly more power barely noticable amounts, then it started to go downhill again should i just keep leaning it bit by bit or what???
and i half almost put a half a gallon through her, followed breakin to the LETTER, i have no idea what to do....

 

[jim]

I tryed one more time and i had to put the LSN all the way in and it didn't have any oompf so i took the air filter off and the idle stop screw was WAYYY off, if was almost half thottle at idle, but u guys new that was coming when you read the first part lol, so i put that back to normal and I got it running OK, but I think the stock gearing is way too high. it took it out on the road and it is too fast for such a newbie, i want to gear it down. what do you guys reccemend for gearing. MY REVERSE IS MESSED UPit works about 30% of the time, I'm getting to FOC on fri but I'm wondering if I'm the only one with a messed up reverse.

 

[sbb4us]

I think the reason you think the reverse isn't working is that the car has to be on be on flat ground and the car has to be stopped. Try this and I am almost positive it will work. Can someone who knows more about how the reverse engages explain more in depth, the guy at my LHS explained it to me a while ago but I forget right now.

 

[olds97_lss]

You also need a relativly slow idle for reverse to work. You can't shift from forward to reverse with any power on the drive train. It just won't let go.

I can't give you any good news about the 2.5 as I only put up with mine for about 1/2 gallon worth of fuel. Hindsight, I should have run it longer. One of those "If I knew then what I know now" issues.

I did drop an OS 15 cv-r(x) in it and I didn't think it had enough power to lumber the maxx around. I've said this about 15 times before, but I would hate to see anyone else make $150 mistake as I did.

I'm now sporting a 21 converted maxx and any power problems I have now are due to having to much power.

 

[SkyMaxx]

The reverse clutch mechanism requires there to be low to no rpms within the tranny. Than means that if your spur gear is flying (regardless of throttle position...as many with metal spurs can attest to the fact that from WOT to idle, the spur can take a while to spool down), you will not be able to shift into reverse.

Basically, no load on the drive train and the thing should work just fine. There have been several instances where the clutch mechanism for reverse just breaks. Personally, I would stick with your plan and get the FOC. You may have to walk every now and again to flip your ride, but the tranny will perform much more smoothly.

 

[SVTSupermaxx]

For the rev. to engage it does have to be "idle'ed" way down. Just go FOC like said above.

As far as running, how many galls you ran? Mine ran like crap until i got about 3/4-1 gall. in it. And finally found a good spot ( btw it liked 230 deg.)

Each engine is diff. Try some diff. glow plugs and you mentioned your LSN. Did you try the pinch test just to get a rough guess?

 

[30%NitroBoy]

Hey Jim - Well welcome to the club, my 2.5's have been a bitch at times but not nearly as bad as your experienceing. They are noticable easier to tune and hold a tune better in smaller truck like a Nitro Rusty.

 

[mrjackass1963]

I had similar problems with my truck when it was new. I bought
a new 2.5 complete engine & it was night & day differance.
I've now have 3 gallans trhough this one and it will keep up with just about anybody! I am getting a piston & sleeve for the
other engine now so I have a spare. I know I ran the 1st one too hot.
I blame the first engine problems on being new to the hobby
& not knowing whats too lean.
The only thing I did different on the 2nd engine is a Nova cooling head.
Don't give up, good luck!