It fired up! :)

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Skwerly

Skwerly

RCTalk Addict
Messages
775
Reaction score
2
Location
Yucaipa, CA
RC Driving Style
  1. Bashing
Well, I took the Maxx to the hobby shop today, after trying for two weeks to start it. The guy took one look at it and said `uh, yuh, this thing won't start... motor's blown to hell.

So I had planned on investing (read: going broke on) in a big block 3.3, but I was smart and went home to ponder it. That's when I remembered that when I acquired the truck, it came with an extra motor. I checked it out thoroughly, and decided to go for it.

I cleaned the heck out of it, then swapped over the head, the motor mount, the carb, etc. I installed the pull-start because that EZ Start gets annoying when the battery dies.

I filled the tank with fuel, popped on the ignitor, primed it, and ZOOM! It fired up after just a few pulls, and idled well, but high.

NOW, on to the questions (sorry).

I ran the thing out front for a while, and it is noticeably faster than the other engine (when it did decide to start), but the idle is HIGH. It's so high that when I put the thing on the ground it takes off on me a bit lol. I backed the idle screw out as far as it would go, played with the needles a bit, still nothing. It isn't exactly screaming, but I know it should be lower.

Once it warmed up it got better, but not much. I also noticed that the back tire, behind the exhaust, was spotted and wet with fuel, which would tell me it is running rich, but I have the thing leaned pretty far out from the factory specs. I'm secretly wondering if the head did not seat right and I have a vacuum leak of some sort, but not sure. I know that would probably create a bunch of heat, but the engine never got very hot (I don't have a temp guage yet, but water definitely didn't sizzle on it).

Any suggestions on how to calm it down? Here are the carb settings:

HSN: 2.5 turns out as per the manual for break-in settings. Should I be 3.5 turns out?

LSN: All over the place lol, with no change whether I go in or out, seemingly. It ended up about 1.5 turns IN from flush, if I understand what flush is. I was trying to lean things out because of the excess fuel that it's apparently getting.

The outside temp was approximately 65 degrees upon firing it and running it for the first time.

I did set the idle withe the brake on, but because it' still idling so high, the brake doesn't exactly stop the car - more like slows it down a tad, so it'll coast enough for me to catch it.

Sorry for the long post, but I'm really stoked that I got this thing to fire! :)
 
Heh, yep, I forgot to mention that, as well. I have the trim at zero, but I suppose that doesn't mean much with an old car and used parts... maybe I should try going to the left of the "0", which I really never considered.

Thanks for the idea, I'll try it out tomorrow!

However, that begs one question: If "0" is the carb's baseline idle, why would there be settings below that? Know what I mean?

I tell ya, I'm having a BLAST with this nitro RC stuff - I really wish I had acquired a car sooner, because I can't remember the last time I had so much fun in the backyard hahaha! :)
 
Skwerly said:
Heh, yep, I forgot to mention that, as well. I have the trim at zero, but I suppose that doesn't mean much with an old car and used parts... maybe I should try going to the left of the "0", which I really never considered.

Thanks for the idea, I'll try it out tomorrow!

However, that begs one question: If "0" is the carb's baseline idle, why would there be settings below that? Know what I mean?

I tell ya, I'm having a BLAST with this nitro RC stuff - I really wish I had acquired a car sooner, because I can't remember the last time I had so much fun in the backyard hahaha! :)
Click to expand...

0 on the throttle trim isn't necessarily the baseline idle for the carb. It's the baseline from where the throttle servo is centered.

If you're 1/5 turns in from flush on the LSN, and it's 65 degrees, it sounds to me like you're way lean on the LSN. It also sounds like you're way Fat on the HSN. But, let me back up and ask, what motor is this? Is it a TRX engine? 2.5? 3.3?
 
SORRY! Yes, it's a TRX 2.5. What are good baselines to test from in say, 70-75 degree weather, which it probably will be tomorrow afternoon when I go back to work on it :).

Thanks for the information on the trim, that makes sense!

Once it is light out and I run it for a while, I'll be able to tell more about what it is doing. I really appreciate the responses, though, this place rocks. :)
 
Pull your air filter and watch the throttle when setting the trim(engine not running). Make sure when you brake the throttle doesn't move. Then you'll know where the trim needs to be when the engine is at temp and idle set.
 
I'm wondering if its an airleak cause an air leak causes more air to be able to reach the engine witch is causing it to rev high i have the same problem with my 2.5 too !
 
Yea, I was thinking air leak as well. I wouldn't have a clue where from though, lol! Now that it's daylight I will have more time to check it out today, and tune the thing and whatnot. :)
 
ahhhh man 70 degrees. where u at man? i would love to have that weather right now. i think its warm when its like 35
 
nice info,my Traxxas engine 2.5 hasn't be running for about a year and when I got it running to day it was on factory break in settings it was working very rich and it was splitting the fuel out and it was running nicely but the tuning wasn't so sweet,I had to return to factory settings twice and my engine was running very hot but I think that I will get him running tomorrow perfectly as I know what I was doing wrong plus my battery pack was empty after 3 tanks....
but atleast I got it running with no problems.
you should check out an Traxxas Website for more info about tuning an Traxxas 2.5 & 3.3
 
Thanks for the advice! I honestly think (hope) that the carb was causing my problems. I could not get it to idle, and no matter where I set either needle, fuel spat out the exhaust. I also believe I had an airleak (maybe still do) and am trying very hard to combat the problem.

Keep us posted on yours, as well. I'm rather new to this hobby, but I have learned five years worth of stuff here in just a few weeks LOL!

My new shocks came yesterday, so I think I'll throw those bad boys on today. I have the 2.5, and upgraded to the 3.3 shocks, so at least the ride will be better while I save up for a carb LOL. They are only about 40 bucks or so, but right now I'm a bit strapped, so here's hoping! :)
 
is there any good bashing spots in yucaipa i am about a half hour from there
 
Actually, I haven't had mine out of the neighborhood yet, but there are a TON of places here locally that I'm going to try out! Beaumont is like 90% nothing but weeds and hills, I test my Jeep out sometimes on the bike trails haha.

Once I get this thing running right I will post up where I abuse it :).

I lived in MoVal for years, and although it's nice, I do like it here MUCH better, even though it's further from civilization LOL!
 

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