skrez

My Feedback: (15)

Hi guys,
I purchased a used os 120ax engine on RC Groups a few months ago. I finally got around to mounting it on a plane and tried starting it today. I left the cowling off the plane so I can check for leaks and so on. The carb was primed and seems to be drawing fuel. The glow was nice and hot and I`m using 10% fuel. I could not get the motor to even pop. The high speed is open 4 turns , and the low speed open about 3/4 turn with the carb completely closed. The motor seemed to be in good shape with great compression. Oh, also I using a bissom pitts muffler. I could not turn the motor over with my 12v starter so I was flipping the prop by hand.Any ideas?
thanks,
Frank

vpresley

My Feedback: (162)

Hi

Might need to clean the carb? Some times they get junk in them. Then change the glow plug just to be sure. How old is your fuel? Could you have reversed the presure and fuel lines? How old is your fuel tank installation? Might need to check it also. Just a few things to check.


Vince

Mr Cox

Check the glow plug and your glow plug driver, you might not get enough heat to the plug. It should at least fire off a prime if you have good compression. The plug needs to glow bright though or it will not be able to fire. If you are using the new handheld ones they have to be absolutely full in order to work.

skrez

My Feedback: (15)

Well so far I checked the glow and it is bright and hot. I did not pull the tank yet, but I betting the plumbing is correct?I will try to open the low speed needle a little more and see if that helps. I would think that it should at lease pop ?
Frank

Mr Cox

Prime until it feels wet, then connect glow driver and it should fire and run off the prime.

skrez

My Feedback: (15)

so far the glow looks good, nice and hot. I`ll try opening the LS needle and see if that works? I`m surprised I can`t even get it to pop?
Frank

Ernie Misner

Is the engine mounted inverted by any chance? In that position priming just causes the fuel to drip down and out, not into the engine. In that case turn the plane over and put a tiny bit of fuel directly into the carb intake. Or just crack the throttle above idle and crank (need the electric starter for this) for a good 30 -60 sec. until it begins to fire.

Do you see fuel coming through the line with you prime it???

Ernie Misner

skrez

My Feedback: (15)

The engine is turned sideways. When I prime, I do see fuel coming thru the line.
Frank

David Bathe

IMO 4 turns out is way to much, start with two out.

SCOTT42

My Feedback: (1)

I agree with david, 4 turns out on the high side is too much, should be about 2 2.5 turns out. Try that and see what happens.

Hemikiller

My Feedback: (125)

You should at least get some sort of pop if the fuel is getting to the cylinder and the glow is good. I have a couple engines that I just squirt a little fuel down the carb throat to prime as the cowl prohibits choking it with a finger over the carb. If all else fails, pull the glow plug and dribble a little fuel into the cylinder. It'll have to fire then.

skrez

My Feedback: (15)

Thanks to everyone who helped me out with this. I changed the HS needle to 2 1/2 out and primed it well and the 1st bump with the starter and the engine fired up. Man this engine runs great and will idle forever. Thanks again to everyone for all the valuable tips.
Regards,
Frank

Ernie Misner

That's one stump puller of an engine. A friend runs a 17x4W APC prop on that engine on his 3D plane!

Ernie