Newb...Having trouble with engine...

[DaveK]

Hey guys,
So I bought this REVO 3.3 used from a guy the other day...he ran it for me when I bought it, everything seemed okay, except that the idle sounded pretty high. He told me it was tuned, and I shouldn't need to mess with it.
Well, the next day I couldn't get it to start for a loong time...and when I finally did get her running, the idle was still super high, and it was getting up to 270 F, so I figured I should park until I knew what was up.
I checked the HSN, and it's 4 turns out, and the IDLE screw is cranked all the way open! I tried to lower it, but it keeps stalling anytime I don't keep it all the way idled up....
Sorry for the newb question....hopefully I'll be a fast learner!
So, any advice?
Thanks a bunch!
Dave

 

[Nitro4910]

There is a great tuning Sticky here.
https://www.rcnitrotalk.com/forum/showthread.php?t=60832#flowchart

Set the Idle Gap @1mm & the LSN flush with the inner ring & re-tune.
You can a #60/61 wire size drill bit shank to set the gap.

You also need to check over the engine, carb, & exhaust for any damage that can cause leaks, fix any defect that you may find.

Drop a new plug in it & tune it.

LSN set flush w/inner ring

Idle Gap should look about like this once set @1mm.

Set gap like this with the drill bit shank, with the slide kept pushed against the Idle Gap screw.

 

[Nitrotrout]

That's the bummer part of buying a used rig, its a crap shoot. You never really know what you're buying until after you've bought it. Good news is that it runs.

These 3.3 engines seem to perform best in the 270 range but not at idle. If your truck is running 270 at idle then you have a situation.

Have you checked over all the electronics and such? They tend to have issues on used rigs from time to time.

 

[DaveK]

Thanks for the info, I printed out the flow chart and I'll be sure and follow it then next time I start the Revo.
270 seemed to be way out of control for sitting at idle...if it matters, the previous owner had the idle screw cranked all the way down, so the idle was set as high as it can possibly go...plus, I think the LS Needle is lean (?), since it is set below the level of the inner ring. If I'm understanding what I've read so far, being lean and having a high idle could make it run hot at idle?
I tried to lower the idle (even a little bit), but then it wouldn't stay running...

I know there's a lot of particulars for me to learn, but I'm still trying to make sense of the basics.
As far as the electronics, everything seems to be okay, I guess...the controller works, the servos work...is there anything else related to the electronics I should consider?
I don't see any obvious defects or damage to the powertrain...but then again, I don't have a trained eye for that stuff yet....the motor is supposedly new, only 5 or 6 tanks through it...he advised me to take it easy for a couple more tanks before I open up the throttle.
When I have some time to work on it, I'm going to set everything on the engine back to default settings and go from there. That's 1mm Idle, 4 turns open for the HS needle, and flush with the inner ring for the LS needle, correct?
Hopefully I can get somewhere after that!
Thanks again guys!
Dave

 

[Nitro4910]

When I have some time to work on it, I'm going to set everything on the engine back to default settings and go from there. That's 1mm Idle Gap, 4 turns open for the HS needle, and flush with the inner ring for the LS needle, correct?

Yup those are the Stock, get it started settings.
I find on my 2.5's the flush on the LSN is too lean & both are turned further out the that.
But @ those settings should get you going so you can tune it.

 

[DaveK]

Thanks so much!
Yesterday after work I put the needles and idle screw back at Stock, and I was able to get it running!
The previous owner had the LSN really lean, and the idle turned all the way up...sheesh.
I did have some trouble getting it started at first, I ended up taking off the Air filter to look into the carb, and I tried to start it like that, and it worked...once it ran for a few seconds, I put the air filter back on, and it started fine after that. I also put a few drops of fuel into the cylinder to prime it...that helped.
Once I was up and running, I got the needles and idle tuned to what I think is a good position...plenty of response, getting a little smoke, idling smooth (and lower), and temp running about 230F-240F...
I ran the tank out of gas, and then it didn't want to start back up, so I brought her in for the night...I'm hopeful that it'll be fine when I try to start it up tonight again....
Is it unusual to have to remove the air filter and prime the cylinder to get a quick start?
I know it must be bad to run the engine (even for a minute) with no filter...so I wonder if I can find another way to get it to start more easily...
Thanks again! I had a blast with it yesterday!

 

[Rolex]

We're glad to hear that you got it running.
Buying used is often a struggle, but if you stick with the advise you get here, you'll be breathing exhaust in no time.
It's not a problem to have the filter off as long as you're not driving it.
An easier way to prime it, and priming is normal with a cold engine, is to put your finger over the exhaust while spinning the starter. That uses the pressure to push the fuel to the carb till it starts.

 

[chickenman242]

if ,and I mean if its just been broken in I would suggest changing the plug ,they tend to get fouled during break in and if this guy had running lean it may have caused the plug to expire early.
I would go for either the traxxas plug #3232x or and os lc3/lc4 ,probably the lc3 unless you are running 30% nitro.
as for the air filter is it clean? ,I would take it apart and check to see if it has too much oil in it and perhaps grab a new one or give this one a clean and a light re oil.

 

[DaveK]

Thanks for the help, you guys...this forum has proven to be a gold mine for good information!
The Air filter is one of those two-part foam units, with a hollow foam cylinder outside and another dense foam cylinder core...I read somewhere that they shouldn't be oiled, just replaced...is that true? I washed it and oiled it anyway, just in case...does anyone recommend a different style of filter? The guy I got it from included a couple of other air filter assemblies, they look like K&N style filters....haven't tried to use either of them.
I'm super stoked to have it running good...my son and I had a blast driving it around the field up the street...it was really cool!
I guess the only thing I still struggle with is starting it when it's been sitting for a day or so...seems really hard to get it running when the motor's cold...does it help to use a hairdryer to warm the engine a bit before trying to start it?
Maybe I'll replace the plug and see if that changes anything...
Thanks again!
Dave

 

[Rolex]

Toss the K&N filters.
What you have is the best. Probably a Motor Saver brand 2 stage filter. The inner foam gets oiled for the dust that was tiny enough to get past the outer dry filter. Usually you can just blow off the outer foam and replace it without touching the oiled filter regularly. You'll be able to see when the inner one needs cleaning.