Engine Troubleshooting Ideas

[bigblueswope]

All,

I'm helping a new guy at the field tune his RCGF engine.

We start it up, lean the High needle for Max RPMs and then go to idle and start leaning the Low needle.

The problem is that as we lean the Low, the idle RPMs rise to 2500-300. We can see the carb arm is closed all the way. If we richen the low, a bunch, the RPMs come down, but isn't that just because we are dumping in too much fuel, esentially drowning the engine?

What would be causing the engine to idle so high?

The carb butterfly does have a hole in it.

That combined with other air leaks around the gaskets?

Ideas appreciated.

P.S. - I KNOW it's a crappy motor, wouldn't buy one myself, but I'm trying to help out a newbie.



BJ Swope

 

[Jetpainter]

I know you said that the arm is closing, but have you looked at the butterfly itself? Does it seat well?

 

[ChickenBalls]

All,

I'm helping a new guy at the field tune his RCGF engine.

We start it up, lean the High needle for Max RPMs and then go to idle and start leaning the Low needle.

The problem is that as we lean the Low, the idle RPMs rise to 2500-300. We can see the carb arm is closed all the way. If we richen the low, a bunch, the RPMs come down, but isn't that just because we are dumping in too much fuel, esentially drowning the engine?

What would be causing the engine to idle so high?

The carb butterfly does have a hole in it.

That combined with other air leaks around the gaskets?

Ideas appreciated.

P.S. - I KNOW it's a crappy motor, wouldn't buy one myself, but I'm trying to help out a newbie.



BJ Swope

Check for peanuts?

 

[bigblueswope]

Lol.



BJ Swope

 

[Terryscustom]

You are tuning it bass-ackwards. Always tune the L first as it controls the bottom 2/3 or so of throttle and the H is mainly combined in the top 3/8.

Richen that H needle to factory recommended setting, you didn't give the engine displacement but I'm guessing it will be about 1.25-1.5 out. (Out of curiosity I'm curious where you are at with that H needle after your tuning?)

With the H at factory (probably a little rich), tune that L for quick transition and a consistent low idle.

Here is the link to the basic tuning process that works 95% of the time assuming you don't have leaking gaskets and stuff: http://giantscalenews.com/threads/basic-engine-tuning.2806/

 

[bigblueswope]

Doh! Thanks Terry. Will do.



BJ Swope

 

[bigblueswope]

BJ Swope

 

[Bartman]

View attachment 46421



BJ Swope

i can relate!

 

[BalsaDust]

Couple buddy's I fly with have rcgf engines. One has the 55 and it looks identical to my dle 55 except it has a CNCed crank case and the dle is cast.

 

[Jetpainter]

View attachment 46421



BJ Swope

We've all been there at one time or another.