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Still Struggeling with Engine- Please help-

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RevoME

RevoME

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Hi Guys,

Revo 2.5R Engine, ran it again today, takes ten to twelve minutes to heat up above the 245's. Thats when I quit, I know at the rate it heats up that it will be above 300 and bust the engine...
History:
Gas Tank Seal was leaking, causing a lean condition, fixed.
Now:
Engine runs and performs fine, but will overheat.
HSN on factory settings and richer at all times. Tons of power, wheelies on demand! But not appropriate for this engine...
LSN on factory settings but idles terribly high, reacts sloppy to LSN adjustments and the LSN is out one full turn from factory settings.
When adjusting, I noticed that my screwdriver could trigger idle fluctuations up to a stall, simply by touching the LSN...
I realize that I am pulling some sick air somewhere, but what can I do?
Carb & Intake are sealed and tight, but this thing is driving me nuts!
Please give me a hint, I'm ready to take the LSN assembly off the engine, but am concerned what expects me there :o)

Thanks Guys!
REVOME
 
Make sure your backplate is sealed as well and that there are no leaks in your fuel lines. If you are unsure about your lines, replace them. Also check your fuel tank for any cracks.
 
robmob said:
Make sure your backplate is sealed as well and that there are no leaks in your fuel lines. If you are unsure about your lines, replace them. Also check your fuel tank for any cracks.
Click to expand...

Rob,

I had the EZ-Start out, but installed it back in, there were no seals?
My problem appears to be somehow connected to the idle needle assbly.
I'll give it a complete over... and post again, thanks!
Any other suggestions, please shoot away!
Jason
 
O-ring could be bad on your low speed needle.
 
robmob said:
O-ring could be bad on your low speed needle.
Click to expand...

I'll check the whole shebang... just wanna make sure I'm not taking something apart that I'll never get back together again :o)
I am replacing quite some stuff, I noticed all the dustboots were bad, he must have sprayed a lot of wd40 which seems to eat rubber! I'll post pics once I get stuck!
REVOME:ale:
 
Revo,

In my youth I was a small engine repairman to supplement a high school boys needs...lol...From the sounds of it...Rob may be right about the O-ring. Especially based on what you said about manipulating the low speed needle...If that ring is bad...I could see where it would create an air leak and stall it out...At least for awhile, I will add my disclaimer that if I am full of it, I apologize...However, based on info you provided and my experience with "small carbs" Mr. Mob may be all over it....

Hawk
 
Last edited:
How much fuel has been through this mill? Chances are if WD-40 was used for aro or to make it look pretty it probably ate the seals.
 
RevoME said:
When adjusting, I noticed that my screwdriver could trigger idle fluctuations up to a stall, simply by touching the LSN
Click to expand...


This is because the LSN is on the throttle arm...You need to adjust your idle screw are your linkage. At idle the throttle arm should be against the idle screw, you should be able to push on the LSN and not have any idle change.
 
What rob was saying about your backplate...take the back plate off, not the ez start, the metal plate under the ez start. That is the backplate. take that off and seal it with some high temp rtv sealant. Doing the backplate and the base of the carb is part of my pre first run ritual.
 
jetmechG550 said:
How much fuel has been through this mill? Chances are if WD-40 was used for aro or to make it look pretty it probably ate the seals.
Click to expand...

She has seen less tha 20 tanks, I knew why I was against WD40...
The truck looks brandnew, except for the rubber boots and that carb problem.
I had it apart all the way to clean it up and found the (i'll call em dusty's) dusty's where all broken. So the newbie tip I will extract from this:

AFTERRUN OIL IS BEST FOR AFTERRUN! Leave the WD40 to your squeaky garagedoors!
:smart: he?
I'll post pics once I get closer to the culprit, but thanks so much!

REVOME
 
RevoME said:
She has seen less tha 20 tanks, I knew why I was against WD40...
The truck looks brandnew, except for the rubber boots and that carb problem.
I had it apart all the way to clean it up and found the (i'll call em dusty's) dusty's where all broken. So the newbie tip I will extract from this:

AFTERRUN OIL IS BEST FOR AFTERRUN! Leave the WD40 to your squeaky garagedoors!
:smart: he?
I'll post pics once I get closer to the culprit, but thanks so much!

REVOME
Click to expand...

Here we go, had the entire thing apart, seals looked clean and very nice. Next will be to put new seals in the carb, and see if that fixes it.
When I took the EZ-Start out and the backplate I found oil and rests of ARO.
Cleaned it all up and reinstalled. I adjusted the idle screws and checked everything as far as linkage. with throttle @ idle the carb shows less than the required .7 mm for an opening.
I don't know, I'll run it later and see if that did anything.
:bow: Thanks guys!
Jason
 
I'll add, in addition to the excellent advice already, that while you have it apart you seal the backplate as RobMob mentioned. Take a bit of RTV sealant and run a small bead around the backplate opening then reinstall the backplate. I put a a bit on an index card then use a toothpick to run the bead. I also use RTV on the carb throat as well. Should help prevent any further air leaks.

May also want to be sure the fuel filter is clean and that if it has an O-ring, that it is in good shape as well.
 
My addition to this is On the HSN assembly, I seal that up as well. I remove the whole HSN assembly and right at the washers I will apply a thin coat of RTV. I mean thin. I will let that cure overnight and then when done screw her down snug. Don't over tighten it as you can tear the seal that was laid down.
 
The little silver screw that comes out of the carburator, right behind the HSN is f***** up, excuse my french.
This apparently adjusts the closed throttle setting.
With everything in the closed position, I adjusted this so the carb would have the 0.7 mm opening, and set everything back to factory settings.
Engine started and ran fine, I need to re- adjust everything, because now throttle response is slow, prolly caused by linkage adjustments I did earlier....
I'll need to go run it somewhere, garage is "unhealthy at best"
From what I saw now, engine performed better, shifted and did not show any signs of cuts... temps slightly high, but below the 240's, and today it's almost 40 degrees...if there is a "factory" setting for this little silver screw as well, I couldn't find it anywhere, please let me know.
I have had engines on airplanes, never, ever had such a challenge tuning one and get it to run steady and fine.
Seems to be a problem if you buy a used rig... you can't screw it up yourself.
But heck, working on it, and especially this place... DO I LEARN A LOT OR WHAT?
 
Last edited:
Are you talking about the idle set screw?
 
jon2 said:
Are you talking about the idle set screw?
Click to expand...

Here is a picture...
Revo_screw.gif


this thing.
 
Thats your idle screw.I hope your adjusting that to set your idle, and not the LSN (The screw on the slider). Sorry, I'm a bit confused - in your posts you seem to be adjusting it for idle, but then you call it your 'little silver screw' kind of implying that your not sure what its for? The LSN does effect your idle when you adjust it, but its by no means what you should adjust your idle by...

Mike
 
SnakEyez151 said:
Thats your idle screw.I hope your adjusting that to set your idle, and not the LSN (The screw on the slider). Sorry, I'm a bit confused - in your posts you seem to be adjusting it for idle, but then you call it your 'little silver screw' kind of implying that your not sure what its for? The LSN does effect your idle when you adjust it, but its by no means what you should adjust your idle by...

Mike
Click to expand...

LOL, I'm going backwards... :hammer:
Yes I do use the Silver screw to adjust my idle.
What I found, was that the idle set screw was out of whack entirely.
Now after having found out that apparently the linkage was adjusted to compensate for the screwed up idle set screw (to use the right word).
From my own post I gather that I mixed the LSN and the idle screw and therfore got extremely confused as well.
I'm sorry. Anyhow, the idle screw sits so the carb has the 0.7 opening in neutral position which I could have figured is correct, everything is back to factory and I'm out running this bugger again. The guy who owned it before me did get me out of my chair for today.
This was my neckbraker... I should have though again right there:
if there is a "factory" setting for this little silver screw as well, I couldn't find it anywhere, please let me know
 

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