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Sluggish when engine is cold..........

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chrisexv6

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Playing around with tuning my TRX 2.5 today. Finally getting it thru tanks without it stalling at all, turned out to be a leaking carb. Carb is replaced now, but I'm noticing that I dont have a lot of power (at all) when the engine is cold. Once it warms up, it screams, but before then its pretty boggy (running rich, doesn't even shift into 2nd for a while).

I dont know if this indicates a worn piston/sleeve, but it doesn't sound like it does (it doesn't stall at any time.........cold or warm), and the engine only has 1/2 gallon thru it.

Any ideas? I've tried going back to factory specs and then taking it from there, but I seem to be ending up in the same spot.

Thanks!!!
-Chris
 
Ya know, most of my rc's are tuned like that. I wish I could tell you exactly how to fix with it but I will tell you to deal with it. I've found I get my best overall when tuned like that. So you burn a tank or almost a whole tank of gas getting it warmed up but when it gets warm, watch out!!!
 
You may still be a bit on the rich side of the sweet spot but thats not a bad thing. It usually takes me 4-5 minutes of warm up laps before I get to temp. I say if it funs well when its heated up leave it alone.
 
Yeah, even my bro-in-law said the thing is sick when warmed up (probably even faster than his brand new one), but before warmed up its a dog.

I have a feeling a Motor Saver and a Big Bore might help it out a little :) give it some oomph even if it is cold.........and I need more fuel, now that its past break-in and tuned pretty well, I can't just run a tank at a time anymore.........thats not enough fun!!!

-Chris
 
I believe that's part of nitro, Chris. Of all the engines, I believe that nitro engines are the most sensitive to their environment. (Temperature, humidity, altitude and barometric pressure.) I baby my 2.5 somewhat and keep it on the rich side. When I first start it up it runs like a dog. After a few laps with the body off, I top off the tank, put the body on, and let 'er rip.

You should have received a small card the size of a business card that outlines the relationship between rich/lean and temp/humidity/barometer/altitude. Keep it. It's the only piece of Traxxas documentation I carry with me in the toolbox. (I might actually learn it sooner or later.)
 
i think that it is that it just needs a little while to get warmed up. that is what my motor does. about 5 mins to get it going and then after that it is good.

bryan
 
My maxx does the same thing. I was told that it's normal. So I just deal with it.
 
Originally posted by wdavidhicks
You should have received a small card the size of a business card that outlines the relationship between rich/lean and temp/humidity/barometer/altitude. Keep it. It's the only piece of Traxxas documentation I carry with me in the toolbox. (I might actually learn it sooner or later.)
Click to expand...

Do you have a scanner wdavidhicks? I would like to see this.
 
Originally posted by mcvickj


Do you have a scanner wdavidhicks? I would like to see this.
Click to expand...

tuning.gif
 
I think it was posted in another thread that even though the humidity changes, it usually reflects the exact opposite change in air temp.........i.e. more humidity feels hotter, but the air temp is really cooler. Thats why 70 degrees at 75% humidity feels so much hotter than 70 degrees at 50% humidity :)

-Chris
 
It feels hotter because evaporative cooling isn't as effective. The reason you sweat is to provide moisture on the skin that can be absorbed by air. As it evaporates, cooling takes place as liquid changes to gas. With higher humidity, the air is closer to its saturation point, cannot absorb as much moisture, and is therefore not very effective at cooling you off.

Does that bend a topic pretty well?
 

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