Posts: 532
Joined: 12/11/2001 From: CanberraACT, AUSTRALIA Status: offline
quote:
ORIGINAL: Mr Cox
What fuel and glowplug are you using? Settings on needle and airscrew? Level of the tank?
Good questions.
Also are you using the small bore fuel tubing that comes with the engine? Makes a big difference I found.
Then, is the fuel clean, ie. use an inline filter. I fried my first GP07 with a tiny bit of crud in the fuel. Sent it for replacement piston/liner, got that plus a lecture on clean fuel :-) Never had a problem after I put a filter in.
I found the GP07 to be a fine little engine. Sure there are things that could be improved, but I reckon you can say that about nearly all mass production engines.
Demon Leather, I'm thinking about a Top Dawg for the GP07 as well, in fact a bunch of us here have bought them (this is my 2nd one) and we are looking for suitable shoulder wing 3ch models. Any other suggestions?
Posts: 120
Joined: 12/11/2001 From: Rex, NC, USA Status: offline
quote:
ORIGINAL: johnvb-RCU
quote:
ORIGINAL: Mr Cox
What fuel and glowplug are you using? Settings on needle and airscrew? Level of the tank?
Demon Leather, I'm thinking about a Top Dawg for the GP07 as well, in fact a bunch of us here have bought them (this is my 2nd one) and we are looking for suitable shoulder wing 3ch models. Any other suggestions?
Hmmm. The only ones I can think of at the moment are he Scientific Shoestring Racer, SIG Stits Flutterbug, and the VECO Lil Pinto. I have all 3 plans. The Shoestring was an all-sheet model for .020 TeeDee power & single channel. I enlarged it to a 32-33" span for an .049 build. The SIG Stits Flutterbug was a constant chord foam shoulder wing with canopy & trike gear. Fuselage was a balsa sheet build.. I think that was for .09-15.. but will have to find the plans. VECO Lil Pinto was a small .010-020 ship, all sheet... gave you the option of shoulder or low wing build. Today, they can either be enlarged or reduced to what ever engine requirement you desire. The only one I could lay my hands on at this time was the Scientific Shoestring, so I took a photo... Bob
PS: Dave Fritzke's site has a few 049 shoulder wings, including the Jr.Falcon. http://my.pclink.com/~dfritzke/ If You're looking for something good-looking to race against a Top Dawg, use this link and D/L the PDF of the "Rivets" Racer. Though it's 020 size, and not a shoulder wing, she IS extremely classy! and has a waay Kool T-tail! The plans will tile print out for you...all you need do is tape them together, and take it to be enlarged., I'd say about 25-35%.. http://www.rcgroups.com/forums/showpost.php?p=10017797&postcount=42
< Message edited by Demon-Leather -- 6/27/2008 5:34:35 AM >
yes a new fuel. I bought it for this engine. I use home brew fuel and i bought a gallon of omega 15% for this because it is recomended. also I used small tube for this. filters are both in the intake and from the fuel pump. the level of the tank and the needle is the same. Ive tried mounting the engine in both upright and inverted. nothing happened
Posts: 532
Joined: 12/11/2001 From: CanberraACT, AUSTRALIA Status: offline
How much running has the engine done Auger1? Sounds like it is leaning out in flight. What about launching it a click or two richer? Are you running muffler pressure to the tank?
< Message edited by johnvb-RCU -- 6/28/2008 2:02:16 AM >
it has ran 13 times airborne and 10 tanks on the ground for break in. yes john i use mufler preasures. two clicks richer is no use. I even tried it 2.5 turns and didn't touched anything. i made a hand launch for it to go. but no matter how rich it is it still leans out and quits. what else do you got in mind?
Posts: 9784
Joined: 11/22/2003 From: arlington,
WA, USA Status: online
A cylinder leakage test and a crankcase pressure test will quickly tell you if the engine is worth working with. If it passes those tests, then the crankshaft fit needs to be checked for proper looseness. It must be free to spin with no axial play. Once you are satisfied that the engine is mechanically OK, then run it with a fuel system that you have checked 100%. Run it on the ground for a full tank. A weak engine [with low compression or crankcase leakage] will not draw fuel well and will die "lean", no matter what you try to do.
by the way when i removed all the parts apart and only the crankshaft in the crank case with the prop on it, it seems like theres a resistance. if i tried to flick the prop it will just make a half turn. is this normal?
Posts: 385
Joined: 7/20/2007 From: Gothenburg, SWEDEN Status: offline
Okay, that could very well be your problem...
I don't know Omega well, but I think they have one version called cool power that people refer to as cruel power. There are modern fuels that have very little oil in them and mainly synthetic. This works only in the larger ball-bearing engines. To little oil in the plain bearing way very well cause the engine to overheat.
I went to the field a while ago with the j3 and gp 0.074. I ask each one of them to give me 1 oz of fuel and tried every brand including home brews. still nothing happens
Posts: 9784
Joined: 11/22/2003 From: arlington,
WA, USA Status: online
Auger, cylinder leakage test is easy. With a little bit of fuel in the cylinder, slowly bring the piston to the top of the stroke. The cylinder should hold that compressed air for at least a few seconds. Crankcase pressure test. It is best to do this test with the carburetor removed. Put a length of fuel line into the intake port and seal it to the crankcase with duct tape. Seal off the exhaust port. Put the engine under water and blow gently into the air line. Rotate the crank as you blow and look for air bubbles coming out the crankcase. A 2 stroke engine will not run right if the crankcase leaks air. Yes, it sounds like your crank is tight. If you flick the prop, the crank should spin fast for a couple of seconds, then come to a gradual stop. A tight engine will give you a 1/2 turn and a quick stop. Make a paste out of sink cleaning powder and oil and use it to lap the crank to the case. You have to be careful about removing too much material and do a very good cleaning of the fine grit paste. It is very important to get all the junk out, putting the engine parts in a jar full of solvent and taping it to a orbital sander will give it a sonic cleaning.
Printable Version
All Forums >> RC Airplanes >> "1/2 A" & "1/8 A" airplanes >> RE: Close look at GP .07 Thunder Tiger 
RE: Close look at GP .07 Thunder Tiger - 
The plans will tile print out for you...all you need do is tape them together, and take it to be enlarged., I'd say about 25-35%.. 
RE: Close look at GP .07 Thunder Tiger -