Tuning of engine...help..

[elmoredarren1]

yes i am new to this but understand it on the engine on my revo stock engine. it runs well but does not idle very good and dies alot. seems to be hot when touch after running... I have the big knob on top to about 4-4.5 turns and the small one under that one is about 2 - 2.5 turns and the one on the side is about flush with the outer housing but just doesn't seem to idle right at all have to use remote to keep it from dying. i live in fort worth tx temp is usually around 65 to 85 outside if you need to know that to help me. also how many drops of airfilter oil on the airfilter for the correct amount. thank you for your help and hope you can help!!!!!!!!!
Thanks
darren

 

[jetmechG550]

Welcome to RCNT. Stock settings is 4 turns out on the HSN and flush with the housing on the LSN. Please check you manual for those, I'm kinda confused when you talk about a third needle. These engines will be hot to the touch as they run about 220-280 degrees. How much fuel have you run through it and what kind of fuel are using (%)? During runs are you leaving a good smoke trail? If you are leaving good smoke, chances are it sounds as though your idle set screw is either not set right (which may be what your referring to) or you may be a little lean on the LSN. Check it and let us know

 

[elmoredarren1]

well i do have a nice bit of smoke and little fuel out tail pipe. on the hsn it is about 4 turns and the lsn is what i think is flush and what should the idle set screw be at and should there be smoke? i am also running 20%. and how do you know if your lean on the lsn and to make it richer is that turning it out past the housing or screwing it in more.. thanks for your help hope you can help me.

 

[SVORay]

Well I'm new also but have run into some issues like this with my Revo.


1) The first thing that comes to mind is how much fuel you got in the tank when this took place and are you running the stock lenght pressure line that came with the truck?

>The Revo seems to have a half tank issues which would cause mine to die a lot once the tank got half empty. This was pretty easy to fix by installing a 9" pressure line and coiling in up out of the way with a zip tie.

2) A bad glow plug will cause it to act like this as well.


3) If you don't have a temp gun/device...get one. These nitros run like stated above around 230 - 270 degress. So yes they will be hot to the touch even when running perfect.

> if the motor is running hotter than lets say 270 to 300 range. It's running lean and will die a lot...usualy did this to me when I only went full throttle.

> if the motor is running cool like lets say around 0 - 210ish...than it's running fat or rich. The extra fuels cools the motor down and causes it to not run well either.

Just my newb experience with the Revo.
Ray

 

[jetmechG550]

Check your idle set by removing the airfilter (engine off) and the throttle trim set to 0 and throttle neutral. The opening in the barrel should be about .020" If that's good and your getting good smoke during runs, run the truck around for a minute or two and bring it in, pinch the fuel line and start counting. The engine should die in about 5 seconds. If it dies sooner, your set too lean, if it takes longer your too rich. If it keeps running, you have an airleak which is also causing you to run lean.

 

[elmoredarren1]

ok i will check that gap today and run it , and do the pinch test. If it is rich or lean i adjust the hsn or the lsn? Hey jet what do you think about this 9" line have you heard of this and he stated to do it on the pressure side that is the one off of the exhaust to the tank correct?

 

[MEGA MAXX]

does it matter if my engine runs at about 200 degrees? or does it need to run at least 220?

 

[vbgagnon]

Youve got to be at 220 otherwise you are causing damage to the engine, and if its a traxx mill you won't be getting any power @200*

 

[Revo Rancher]

After break in you need to be about 220-240 for best run performance. If you get past 270 you are too lean, most likely on the HSN.

As to the 9" fuel line, I have never heard of that. Can you explain what was told to you (and where you heard it) and what it is supposed to do? Maybe then we can advise better. I think someone told you to add more line to the pressure line coming off the fuel tank to the pipe, but I want to make sure before I answer.

 

[MEGA MAXX]

Youve got to be at 220 otherwise you are causing damage to the engine, and if its a traxx mill you won't be getting any power @200*

I'm getting great power at 200-210.

also my idle seems to rev up and down? I'm guessing I've got the mixture wrong somwhere.

 

[Revo Rancher]

Mega, 200-210 is still a bit low, You might be doing a disservice to the life of your engine as it will cause premature wear when it is too low, same as being too hot.

The flutuating idle is most likely due to an air leak, causing a leaning condition, or your servo batteries are getting low. Or maybe a minor glitch. To check for the last two, take off your air filter for a moment while the Tx and Rx are switched on and see if you can see the servo moving the throttle and carb at all. It may look like it is twitching. If it is, then you have either low batts or interference caused by metal to metal contacts somewhere.

 

[MEGA MAXX]

nah there isnt an air leak (or my temps would be high). and i have fresh batts in both.

it just revs up like its lean and then goes normal, revs up , goes normal and so on.

it might just be cos its cold outside (about 5 deg C), but my temps are rising while at idle?

 

[vbgagnon]

Wether you want to admit it or not you have an air leak somewhere.

 

[Monkey Wrench]

Like VB said, it's an air leak somewhere.

First place I'd check is the O-ring on the fuel tank. The Revo has a known issue with that gasket crapping out fairly quickly. Personally, I'd replace it outright, just to remove on variable from the equation.

Second, check and/or replace your fuel lines. Even the smallest little hole can allow enough air into the system to cause that quick lean condition you describe.

Third, if you have the time or when you need to pull the mill, apply some RTV sealant to the carb. throat and backplate. That'll button that mill up good from any air getting in there.

Anyhow, hope this helps! Good luck!

 

[MEGA MAXX]

ok, ok. ill have to bite my lip and say......yes i have an air leakpps:

I've accidentally caught the fuel line goin to the carb with some scissors when cutting a cable tie.

hopefully...this will have sorted it.

 

[olds97_lss]

I know this is an old thread, but I have the same kind of idle problem. Once the engine warms up (runs around 220-240), after a high speed pass or just putting around (nothing WOT), I get a idle that fluctuates badly. It eventually dies if I don't give it some gas. It will drop really low in RPM's, then go high enough to engage the clutch. Each time it drops low, it drops lower and lower until it dies. It will die in about 20 seconds if I let it.

I've replaced fuel lines, replace tank seals, replaced header coupler and header gasket, sealed backplate with RTV, sealed carb neck with RTV. I'm about 4.5-5 turns out on HSN and 1/2-3/4 turn out from flush on the LSN. If I set the high to 4 and the low to flush, it's way too lean and flames out after a short time. I've also taken the fuel tank off, pressurized it under water and no leaks. I replaced the o-ring in the tank cap anyway just in case.

I'm running 20% trinity MHP and an OS #8 plug. The ambient temps are around 45F, engine temps during typical driving fluctuate from 210-240. I might try a #3 plug today just to see if it "needs" a hot plug.

Any suggestions? I've been into nitro for about 6 years. I've had 12-14 engines on different vehicles. Small block, big block. Any time I've had an idle problem or overheating problem, it was an air leak and doing everything I've listed above has fixed it. I'm kind of stuck...

 

[jetmechG550]

Wrong plug. OS 8 is a cold plug, if your running a small block use a McCoy MC-59 or and OS LC3. I'm not sure a OS3 will work, it's not a long reach plug.

 

[olds97_lss]

According to the OS chart, the #8 is medium-hot. #5 is cold.

I tried a MC-59 a few weeks ago, but it didn't make it run any better.

Actually, I don't have any #3's... I thought I did. I checked with my LHS and they suggested this one last week: http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXEXW7&P=7

I'll give it a go today and see how it likes these.

 

[jetmechG550]

Sorry, had the P8 and 8 mixed up.

 

[olds97_lss]

Yeah, this one sucks... http://www2.towerhobbies.com/cgi-bin...?&I=LXEXW7&P=7

I went back to a #8 and fiddled with the HSN and LSN. I think my HSN is still about 4.5 turns out and the LSN is 3/4 turn out from flush. It runs ok and has decent power, but the idle is still kind of erratic if I let it sit for more than 15 seconds without gassing it. It acts rich on the LSN, but when I lean it out, I can't get the idle to drop.

Oh well... when it dies, it's getting pinched and shelved because I want to throw a 3.3 in it.

I really dinged up the header. For some reason, it seemed to run more consistent with a big dent and bend in the header...