Revo revving high, running slow.

[adxdopefish]

Hey guys.

More problems with the Revo. So far nothing has been too dramatic, and fixed easily. The other day driving around I thought I heard the pitch of the engine change a little. I was about to run the tank dry so I thought it was just the normal noise of the fuel running out. The fuel tank then did in fact run out and I thought all was normal.

I have just fired the machine up again tonight and can now confirm that something is very wrong with the truck. I had a hell of a time trying to tune it so it would even start. It has to be running so rich that fuel is sputtering from the exhaust pipe, or else it just won't start. Tried all default settings on all three needles, no start.

After tuning it to a point where she will actually run, I can finally drive it without stalling, and the revs really get up there in a big way, but the truck is SLOW. A friend of mine with a Revo was out with me tonight so we ran the trucks side by side. Mine was making a lot of noise and not moving fast, and he was just being gentle with his around the car park and it was flying as per normal.

I am still very new to the scene and do not know what could be causing this problem. I tried looking around the forums and on Google but could not find anything like this.

Any ideas guys?

Thanks,
Brad

 

[itsalifeworthliving]

your problems are just normal "newbie" problems.. wants you get the tuning down, it will be a breaze. keep in mind that tuning is a regular accurance as tempatures and humidity change even from day to day.. so try to do as much home work on it as possible and ask plenty of questions.. a simple fix for your motor reving.. check your slipper clutch, its the large gear next to the clutch bell. youl see a nut set up with a small thick spring. if you hold the gear and give it a little twist it will tighten up. it is desireable to have some sort of slippage under harsh landings and so on.. it will protect your drive train. as far as your tuning go's. your revo should start from stock settings unless it is super cold outside.. I've been using the stock setup as a referance on traxxas motors for many years, and it never fails.. try not to mess with the idle screw. that could throw all your tuning off.. most idle problems are coused by you low speed needle anyway. GET A TEMP GUN!! it sounds like you dont have one. it is much easer to tune to temp then, sound and feel.LOW SPEED NEEDLE.. stock setting is "flush" with the inside. that is a direct root of hard starts(besides a glow plug). once you get it to idle and run smooth, THEN go to you high speed needle.. dont forget about the glow plug. they arent always good or bad.. if they are "almost" bad, you can have a diffucult time starting.. when it dought... just replace it.. it will save you alot of agrivation and frustration. in the end, you will have many spare glow plugs. tuning takes plenty of practice. youl know when you start to get good. youll be able to run tank after tank with a simple temp gun and screw driver.. it will get easer, but try to focus on the tuning aspect then the driving aspect for a little while.. good luck, and keep the questions coming...

 

[Cupooterluvr]

:goodpost: He's right. Tuning is very easy after a while, and you develop something of a "reflexive" effect, where if the engine does this then you automatically do that. It really helps if you have an expert there to show you what's going on. I know that before I met my neighbor Brian I was totally noob in every aspect of tuning, but then he tuned my engine perfectly and from then on I was an ace at tuning.

 

[adxdopefish]

Problem solved.

Problem solved, I think.

I had the truck outside after work but it was getting dark very quickly.
So it turns out that as much as I thought my tuning was correct, something was off and that was the cause of my stalling issues.

After I had that sorted, I moved onto the speed problem, and found it to be caused by the slipper clutch. I've never touched the slipper clutch before and have not really used the truck all that much. I tried turning the spur gear with my fingers (i THINK it's the spur gear) and noticed that the slipper was letting it turn easily using my fingers to move it. I thought that if I could move it that easily with my fingers, then imagine how much it must be slipping when taking the huge power from the Revo TRX 3.3.

Tightened the slipper clutch, ran it again. She's back to normal, absolutely flying... Maybe this thing was way too loose from factory, because it feels faster than it has ever been.

Thanks again for all of your help. You guys are a great team.

-Brad