CRRC Pro GF26I

[Wingman26]

Thanks!

[joseae]

I don't know how many of you have the same problem but I am having a hard time setting up the low the idle. I find that every time it transitions from high to low, it takes a while to finally slow down to the preset idle. Then if I trim the idle lower it keeps coming down until it reaches under 1750 rpm and stops. I have tried different needle settings but nothing seems to work.

[Jedijody]

You are to lean and or have an air leak.

[joseae]

Last time I ran it I ended up setting both needles back to factory settings. Judging by the exhaust, if anything, it may be a little rich. I will check for air leaks. Could timing have anything to do with it?

[Jedijody]

I've never seen one do that and not either find a cracked insulator, leaking carb or insulator gasket, or be able to adjust out with the needles. It's possible I guess for the ignition to cause it but I've not experienced it before. Did you have the carb off for any reason just prior to this happening?

[3Dguy]

I had an air leak in mine once. I couldn't get the engine under 3,000 rpm without killing it. The insulator block was ok (but I've heard of problems) it was just a gasket that I forgot to change out after removing the carb...

[joseae]

	Quote: Originally Posted by Jedijody
	I've never seen one do that and not either find a cracked insulator, leaking carb or insulator gasket, or be able to adjust out with the needles. It's possible I guess for the ignition to cause it but I've not experienced it before. Did you have the carb off for any reason just prior to this happening?

The carb has not been off but it has vibrated loose a couple of times. I just can't recall if the idle problem was there prior to that. I guess I will have to remove the whole carb assembly and check for cracks in the insulator and gasket. Is it safe to use thread lock on the carb and insulator bolts?

[davidjensen]

Had several flights on the 26 today with an APC 17x8. I tached it at only 7600 rpms and it ran well. I pulled the cowl and spent a lot of time moving the high end needle to see if I could get more rpms but was unable to. I will go back to the 17x6 but doubt I will ever see over 8500 rpms with it. Gas was 89 octane with 50:1 lawn boy.

[flymoor]

You do not need 8500 that would be too high, the best power on the 17x6 APC is about 7800-7900, plenty of power . Have a great day
Rich

[2robinhood]

	Quote: Originally Posted by flymoor
	You do not need 8500 that would be too high, the best power on the 17x6 APC is about 7800-7900, plenty of power . Have a great day Rich

I wouldn't say that.
I know every plane will fly different with different props, that what in flight testing is all about.
I have tested many many props on the GF26I.
In my personal findings, my APC 17 X 6 was @ 9450 rpm and was the prop out of all that I tested for sport and the 3D flying that I am able to do ( still learning 3D ).
I found that the more rpm's I turned the more power I produced.
I know that prop efficiency , size , and shape come into play, but like I said, the APC 17 X 6 @ 9450 rpm was the best performer.
Here is a list of props and rpm reading that I took.
I am @ just above sealevel and running the CRRC Pro pitts muffler.
Rpm numbers did change as the engine broke in ( they gained ).

Master Airscrew Classic 16 X 10 @ 7800 rpm
SY 16 X 8 @ 9000 rpm
Xoar 16 X 8 @ 8400 rpm
APC 17 X 6 @ 9450 rpm
Xoar 17 X 6 @ 8400 rpm
Xoar 17 X 8 @ 7500 rpm
Xoar 18 X 6 @ 7750 rpm
Master Airscrew ( wood ) @ 7200 rpm
APC 18 X 6W @ 8000 rpm
Xoar 18 X 8 @ 7400 rpm

[2robinhood]

	Quote: Originally Posted by davidjensen
	Had several flights on the 26 today with an APC 17x8. I tached it at only 7600 rpms and it ran well. I pulled the cowl and spent a lot of time moving the high end needle to see if I could get more rpms but was unable to. I will go back to the 17x6 but doubt I will ever see over 8500 rpms with it. Gas was 89 octane with 50:1 lawn boy.

I never tried a APC 17 X 8, but you are down about 2000 rpm from what I was getting with the APC 17 X 6 and about 1000 rpm off with the same prop.

Hard to give you a reason, without seeing and playing with the engine.
What muffler are you running?
How is your idle and transition?
How much fuel has been run through the engine?
Where are you in regaurds to sea level?

[joseae]

This is kind of strange, according to your list you are getting 9450 rpm with a APC 17 X 6, I can only get about 8650 rpm tops with the same prop. On the other hand, with a Xoar 18 X 6 my engine was at about 8300 rpm compared to 7750 on yours.

[2robinhood]

What carb is on you engine?

[RappyMan]

One of the old pros on here posted a simple way to set the needles on the carb. Turn both needles out 2 turns (from closed.) Set the high needle for best rpms. Go to idle and start leaning it up - it should start picking up rpms. Put the low needle at the point of highest rpms at idle. If the transition is okay... you are done.

I set up a 50cc this way and it was easy to do and runs good.

[davidjensen]

The only reason for the lower RPM I can find is a sizable scratch on the cylindar wall right above the exhaust port.