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Problems tuning

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SkurvyPirate

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I am new to the forums but I thought this would be a great first post since I have spent two days trying to get this beast running.

I recently took over my brothers Tmaxx which he ran a few dozen times before it got stored away for a couples years. I have driven it before a long time ago and remember a lot about it. I have also read through the manual and done a lot of forum reading. But I am definitely new to the scene.

First off, I have been having a blast and in three days have already had to replace the lower suspension arm twice and the bulkhead and some screws (whoops!). Been trying to tune it up and down my driveway which is gravel and in the country but rough and lined by trees haha.

Here is the problem, whenever I seem to get it tuned right it ends up being too lean and the engine smokes and it has even stalled out. Then I richen it back up and it gets sluggish. I am doing 1/8 turns and everything. When it seems like it is in the zone where I want it, and before it gets too lean, it runs ok but the engine won't rev up at high speeds.

I will hit it full throttle and it takes off then it seems to hit a wall or bog down maybe a little bit with the throttle still full for 3 seconds or so, then it revs up to higher rpm and then shifts into second. I have read that this condition could be from it being too lean, so I richen it up and it becomes very sluggish as I said above.

I just feel like I can't find it's happy place. I am thinking of just turning it back to factory defaults and giving it another try from there. Any other suggestions?

Oh and I just bought a temp gun today so I will be able to more accurately tell if it really is running too lean or what is going on. Sometimes when the engine smoke I think it is just excess WD-40 from my post run care.
 
i wld suggest going back to factory settings..

Is the engine sealed..??

If its a traxxas motor i wld highly recommend sealing it to stop all air leaks :)
And now you have a temp gun that will help alot more.. Dont let it get over 290-300 if possible try to keep it at 270maxx..
i have heard that if it does get hot not to shut the engine off completly but to let it sit there and idle for a minute or two.. but dont quote me on that one.. thats what i do but i cld be doing it wrong..? maybe some1 else can shed some light on that issue

Goodluck :)
 
How do you seal it? I worked on it today and set it back to factory and started tuning from there. Some problems I'm having:

1) it seems to stall out after I let off the throttle sometimes like it idling too low. Which it could be and I have adjusted the screw a little but I don't want to anymore because it jerks just sitting there now.

2) it seems to be pretty well tuned except sometimes it still kinda hits that wall before it shifts. It used to every time and now its about 1 in 4. I'm afraid to lean it out anymore, I have it about 1/4 turn past factory but with it dying I don't want to lean it more right now. The temp has only reached about 230 to 240 max through all of it though

3) after it stalls out it doesn't start back up right away (which it would always do before). Which points to overheating but I don't think it is as its only gotten up to 240.

Any suggestions on what to try? I will look into sealing the engine also.

Sent from my Droid
 
Lean your low speed needle about 1/8 of a turn and see how it does. And get a fuel brand with rust inhibitors mixed with it. I have found that using WD40 for after run tends to shorten glowplug life. I get twice as many tanks out of them since I stopped using it.
 
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I ran it today and it was running about as good as I have ever seen. The only thing is that it is still stalling out after I have been running it a bit. It was only getting up to 220 max so it's not overheating.

I guess next thing I'll do is seal it when i get the time. Thanks for the advice. I'll post back how it turns out.

Sent from my Droid
 
Well if it's been sittin for a while it may just need the cob webs blown out of it! Sounds like to me it gets better every time you run it.
 
Well I ran it today again and I think it is perfectly tuned but it is still stalling out after a few WOT passes.

I'm beginning to think it needs a rebuild, it's showing all the symptoms:
1) Hard to start when warm
2) Stalling out when warm
3) Stalling when letting off the gas

My question now is should I buy the piston and sleeve for a rebuild? Or do the Traxxas engine replacement?

Sent from my Droid
 
Do u live in the US...??
If u are i wld do the replacement option..
I live in Australia so it takes a long time to do..
If you do buy a new piston and sleeve make sure you get the conrod aswell..!!
But you will probably find that for the price you might as well buy a new engine for just a few more $$
 
A piston and sleeve is like 34 bucks. But I might a well just trade the whole thing in for a replacement and spend 40 more.

Last question, should I get the same 2.5 or upgrade to the 2.5R or even 3.3? If I got 3.3 it would mean a lot of other parts right?

Sent from my Droid
 
i just did this same thing and i chose to upgrade to the 3.3. the stock 2.5 parts will work just fine under moderate use. (but with the add torque and power of the 3.3 you may find it hard not to get on it). i left everything stock and just plan on upgrading as the parts go. but theres nothing wrong with another 2.5 and if your lhs is like mine you can only get 2.5r or 3.3 anyway no more standard 2.5's. the choice is urs but i think most would agree for the price difference upgrading is worth it. just my 2 cents. hope it helps .
 
There's no difference between the 2.5 and 2.5r they are the same motor. If it were me I'd pop for the 3.3. I wouldn't bother with the exchange program you can find em all day long on ebay a lot cheaper. Then I would rebuild the 2.5 and either sell it or put it in something else, but that's just me. It's up to you on what you wanna do.
 
cwal1774 said:
There's no difference between the 2.5 and 2.5r they are the same motor. If it were me I'd pop for the 3.3. I wouldn't bother with the exchange program you can find em all day long on ebay a lot cheaper. Then I would rebuild the 2.5 and either sell it or put it in something else, but that's just me. It's up to you on what you wanna do.
Click to expand...

+1 on that..
3.3 all the way.. upgrade if/when parts break
Rebuild the 2.5 and sell or drop in another rig :)
My GF just put a 3.3 in a standard TMaxx and so far all is good
 

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