tunning a Maxx 2.5

[godale03]

Is there any one out there that can give me some advice on how to tune this motor? It doesn't really cut out on me, but it runs sluggish and I can't get it to idle for anything. It wants to constantly jump forward, and I have to feather the gas to get it to excllerate. Any suggestions? Thanks

Nitro Newbie

Tom

 

[jon2]

ok first of all is this a new 2.5 maxx? If the engine is new did you break in the engine? Have you touched the needles at all? What fuel? What Plug? What is your weather condition? A few things are needed to help you out.

I await your response!

Jon2
RCNT Staff

 

[godale03]

Jon2,

It is the new 2.5, and yes I have run it through the Traxxas recomended break in period. Actually I have run 6 or 7 tanks through it. I have not adjusted the needles at all. Everything is still as it came to me in the box. I am running 20% topfuel, and my next gallon happens to be Monster 20%(the LHS was out of Traxxas fuel). I am using traxxas long heavy duty plugs. Right now the weather is cold, I am in MD. I am not running it much because of the cold, and the fact that my fail safe is still on order. Can I even run the Max in the cold? If not, what temp should I run the motor in? Thanks for all of your help in advance. I know electric, but Nitro is a whole new ball game. Thanks.

Tom

 

[dave]

i also live in MD and its been pretty cold. I think you should try and break it in a few more tanks when it warms up if you didnt follow the winter weather break in section. If you broke it in when it was that cold the piston probably hasnt expanded into a direct fit yet. if its jumping foward then turn down the throttle trim and use the idle screw on the carb to adjust it. I havent had any problems with mine yet i didnt tough the LSN and my HSN is 3 1/4 turns. i suggest that you adjust the carb instead of using factory settings

 

[baldie]

If you are breaking it in in cold weather, it is best to cover the cooling head with a piece of paper or perhaps a baby sock, but don't cover the top of the head. Also try to invest into a temp gauge. I did and it has helped me a great deal. Running temp should be around 240. Being your in cold weather it might be hard to get that reading. It is important to be around that temp so engine wear is minimal. From what I understand, if the running temp is in the 100's, although it might seem good, it can wear your engine out fast.

As for your tuning issue.....put the HSN at 3 1/2 turns out from closed. Put the LSN flush with that pieice sticking out and pointing down to the left. Make a couple full throttle passes, and turn the HSN 1/16 clockwise until you do not see any performance changes. After each adjustment, make a couple passes. If you don't see any smoke from the pipe, the temp is above 270, you see smoke coming from the cooling head, or it cuts off at full throttle...then you've adusted it too far. In this case, you will turn the HSN 1/8 counterclockwise until any or all of the above is gone. At this point the HSN is set. You will then adjust the LSN. Pinch the fuel line. Normally the engine should cut off in about 2-3 seconds, if the LSN is set correctly. If it takes more than 2-3 seconds, turn the LSN clockwise just slightly and try it again. If it cuts off right away, turn the LSN counterclockwise just slightly. Adjust until the engine cuts off 2-3 seconds. As for the idle adjustement. You want the idle to be as low as possible without it dying on you. This should help your creeping problem. Also make sure your throttle trim on the radio is turn all the way down before making the idle adjustments.

I'm a newbie like yourself I've learned alot from these forums and have only gone through 8 tanks through my tmaxx. I followed this instructions from the moderators here and my maxx has been perfect. Just be patient. My tmaxx would cutoff on me here and there also but its all normal. Sometimes new engines have hiccups and it just takes time. Once the engine is completely broken in, you should have any problems. Being that you are in MD and its cold, it may not get better for you until the weather warms up. Just my 2 cents.

Is there any one out there that can give me some advice on how to tune this motor? It doesn't really cut out on me, but it runs sluggish and I can't get it to idle for anything. It wants to constantly jump forward, and I have to feather the gas to get it to excllerate. Any suggestions? Thanks

Nitro Newbie

Tom

You have the same problems I had when I first got my maxx. The sluggish and the excelleration problem is more than likely an LSN adjustment. Once you fix that adjustment and the HSN...yoru idle problem will be fixed as well. Read my last post for some pointers.

 

[.21Rc10GT]

Baldie!! Looks like Rolex turned you into a Genius!!!!

 

[Tarant]

just curious but did u read the manuel or watch the dvd.
Cause when I got my maxx for the first time I knew absoulutly nothing and I read and watched and I have never once had as many problems as so many people seem to have

 

[Rolex]

Baldie!! Looks like Rolex turned you into a Genius!!!!

LMAO......Thanks Baldie. I guess I can take today off.

Just one correction. The idle. You don't want it as low as possible, you actually want it as high as possible without making the car creep or the clutch chattering. The higher the idle, the more stable the engine runs.

 

[baldie]

just curious but did u read the manuel or watch the dvd.
Cause when I got my maxx for the first time I knew absoulutly nothing and I read and watched and I have never once had as many problems as so many people seem to have

Not all engines will run the same. Some will run perfectly and some will have minor problems.

Baldie!! Looks like Rolex turned you into a Genius!!!!

Just trying to return the favor....hahaha. It feels good to know how to fix things now. Of course I'll probably run into things in the future I'll need pointers on.

 

[Rolex]

I've seen most of the problems with tuning because they run the minimum amount of break in, and then want to make it absolutely RIP instantly. Anytime I've helped someone break in a new engine, I follow the manufacturers specs for each tank. After the 4 or 6 tanks for break in, each tank after that gets tuned just slightly, and performance tuning doesn't come till tank 10 or 12.
No matter what you've heard about breaking in, no engine is at its' peak till its' had at least one gallon through it.
A lot of engines go through a 'stubborn' period after the break in, but when someone does 4 tanks, then starts to make major adjustments to both needles for racing performance, that's where the trouble starts.
Too many adjustments, too much adjusting at once, and with both needles and the idle. If they're new to nitro engines, they get lost on what they changed, and being unfamiliar with the carb adjustments they don't know what needle adjustment corrects each symptom.

 

[godale03]

Baldie, Rolex, and Crew,

Thanks for all the suggestions on Tuning the motor. I actually ran the break in during the last couple of weeks in August. I have not run it this winter except for the couple of days that the temp was above 45. I have ordered a temp gauge from my LHS so it should be here by Wed.... I hope. I have been very leary of running it in the cold because of my inexperience. I will do exactly what you guys have suggested and report back on my progress. I usually pick up things fast... usually. I had no problems with Planes but land based is posing a real challenge. Thanks again guys.

Tom

 

[Rolex]

I've flown planes for many years. They are effortless compared to these.
Break in the engine at high throttle, then set it and forget it. They are a lower RPM, and have a constant cooling source.
The trucks work very hard moving a lot of parts and mass, and are subject to tougher conditions.