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Old Jan 16, 2012, 02:25 AM
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southern oregon
Joined Feb 2010
52 Posts
NGH engines

Mr. Chow, I purchased one of your small gas engines from Agape hobbies and Racing and it has the walbro carb. It seems to run okay, but can't seem to get the radio interference to quit. Have had to shut the plane off with the electronic kill switch three times now and managed to save most of the pieces. Not the best feeling.. Seperate batteries, 2.4 JR, ignition in the front of the 80" cub, radio behind the wing. The nice folks at Agape advised me to twist the spark plug cap to eliminate the interference problem. I checked the owners papers again and still no reference to this problem. I have received a new OPTO switch and will try it again. Does the plug cap need a ground wire soldered to it? The plane gets in the air, flys for about one lap to gain about a hundred feet of altitude, and when the throttle setting is changed to slow the engine down or go to cruise, the plane immediately goes into a stunt show mode on its abrupt way to the ground. When the opto switch is used, the engine quits, and you can regain control of the plane for the rest of the way to the ground..... Not a great introduction to flying with gas... Any advice from the experts would be appreciated. The comments from the gallery at the field are not the best regarding this set up. Sincerely Randy Shaw
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Old Jan 16, 2012, 05:42 AM
Registered User
Kansas City
Joined Apr 2010
606 Posts
A loose cap can cause this issue. I have used a common hose clamp around the cap to firm it up. Has worked for years with no more problems. Best regards.
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Old Jan 16, 2012, 05:50 AM
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flypaper 2's Avatar
Kingston, Canada
Joined Jun 2004
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It could be a bad plug ground as you say especially when you say it starts or gets worse when you throttle back. It may be hitting a resonant speed. if it is that, which I have had to fix before, is to solder a wire to the wire loom over the plug wire or to the plug cap itself. Just to find out beforehand you could clip a jumper wire with aligator clips from the wire loom to the crankcase. Wouldn't be a bad idea to put the wire permanently on it anyway, just for insurance. A resistor plug would also do it but I don't know it they make one for this size of plug. Hope this helps. One of the guys in the club thought the plug cap was to tight so he took the wire clamp ring off the plug cap and raninto this problem. I put the ground wire to the plug wire and it solved the problem.
P S. The screw clamp works as Lifer says too but I didn't whether it would fit over this plug cap.
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Old Jan 16, 2012, 09:29 AM
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Kansas City
Joined Apr 2010
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The advantage of the hose clamp is that it is cheap, and usually works!
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Old Jan 16, 2012, 03:32 PM
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United States, OR, Portland
Joined Jan 2008
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So I -could- actually possibly use this or a similar gas engine on my Pete n Poke, since I know people have put .56 4 cycles in one. Probably would have to use a smaller fuel tank to fit the pump behind the firewall. Just thinking out loud.
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Old Jan 17, 2012, 01:43 AM
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southern oregon
Joined Feb 2010
52 Posts
NGH ignitions VS radio receiver

Gentlemen, thanks for the suggestions. I will try the wire with a clip on the metal plug cover. And you are right, there is no resister plug in this size application. I may be able to run it long enough to see if the transition stage in the Walbro is okay or not. My particular engine did not come with a fuel pump, but a hose connection from the crankcase to the Walbro in front of the cylinder. I will put the new ignition kill back into the plane as that was all that saved any of it. Just pulling the trim down on the throttle servo would not be quick enough to save the plane. The Opto switch is instantaneous !!! Regards, Randy Shaw.
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Old Jan 17, 2012, 01:48 AM
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Joined Dec 2011
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Mr. Randy, sorry for this problem.
there is a spring inside the cap, please check if it is in. and check if the connection is loose.
and please check if sonewhere of the carb or crankcase leak fuel, if air into via somewhere, it is this.
please tell me which size it is. michael
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Old Jan 17, 2012, 05:31 AM
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Kingston, Canada
Joined Jun 2004
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Randy: Yours, with the Walbro carb, has the fuel pump built into it. That's where the fuel line connects to from the crankcase. The crankcase pulses operate it.
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Old Jan 17, 2012, 08:49 AM
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Keller, TX
Joined Aug 2005
299 Posts
Randy, the most likely cause of your problem is that you don't have the spark plug cap on all the way. Snug is not enough, it has to be very firmly pressed on. Bare handed is usually not enough for me, I need to use a cloth or some kind of cushioning on my hand to fully seat it.
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Old Jan 17, 2012, 02:12 PM
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southern oregon
Joined Feb 2010
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NGH engine

My engine is a model GT17, ser. # 171104005 purchased from Agape Hobbies on 6/6/11. As soon as the weather clears I will try the ground wire method as it would seem to be the most reliable, and verified so I won't get any more suprises. By the way, Agape Hobbies are real nice people to deal with and I enjoy their service. Randy Shaw
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Old Jan 18, 2012, 08:08 PM
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Joined Dec 2011
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Sir. keep in contact if you have any doubt, every problem will be solved for you. Do not worry.

It seems the "key" Fuel-delivery-system work well for GT9.

http://s1207.photobucket.com/albums/...rent=PT-19.mp4
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Old Jan 20, 2012, 02:00 AM
UAS Pilot/Tech Instructor
CryHavoc's Avatar
United States, CA, San Diego
Joined Apr 2000
1,422 Posts
Just got my '9 today. 4 days from Himodel to San Diego. Paid $200 total. I chose DHL express. Hope to get it broke in this weekend.

I posted some very interesting videos, on page three of this thread, from a guy called Surats on Youtube running this engine. Seems to run slightly better using muffler pressure instead of the pump.....Especially the throttle response. Must be some pressure lag in the pump but I did notice he was using some very long fuel lines. The manual has a supplement sheet that is pretty specific on pump placement and fuel line length. Anyway, should be fun.

Later,
Mike
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Old Jan 20, 2012, 02:08 AM
UAS Pilot/Tech Instructor
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United States, CA, San Diego
Joined Apr 2000
1,422 Posts
Quote:
Originally Posted by seeingeyegod View Post
So I -could- actually possibly use this or a similar gas engine on my Pete n Poke, since I know people have put .56 4 cycles in one. Probably would have to use a smaller fuel tank to fit the pump behind the firewall. Just thinking out loud.
The power output is around the same as a .50something Four Stroke so I think it would be perfect on that plane. Its no bigger than current .46-50 engines so it would fit physically with no problem.

My buddy built one of these and there is plenty of room to shift things around for the ignition and extra battery. Not to mention the wing area to carry the extra weight. Like you said a slightly smaller tank would help. Just remember you'll have to build the tank with gas friendly stopper and fuel lines.

Mike
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Old Jan 20, 2012, 02:25 PM
Demonstrations on Saturdays!
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United States, CA, Woodland
Joined Jan 2012
344 Posts
Got mine this week from Hi Model, same 4 days by DHL to Sacramento area and breaking in this weekend.

Found a deal on an old Orline V tail Bonanza .40 size and will fit just perfect. Will need to build a small bubble on the cowl for the plug wire but nothing extreme.

Chose the gas for weight issues hoping the smaller fuel tank would help offset the adding of retracts, flaps, full interior, lighting and CD player with 12" subs! Ok no CD player but everything else. Plus I hate nitro!

I've been waiting for gas to evolve to a reasonable level to get into it. Never was anxious enough to gut a weedwacker an convert it.
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Old Jan 20, 2012, 04:11 PM
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United States, CA, San Diego
Joined Apr 2000
1,422 Posts
Hey Gravity, your model sounds good. I'm gonna put mine in an ARF Kawasaki Hein. The engine will stick out but its an ARF and I just want try the engine for now plus I wont have to deal with possible cooling issues while I figure it out.

Mike
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