2 Stroke HELP!!!!!!
 

I have a Magnum 1.8 2 stroke that I need help with. It has standard carb with low end in carb barrel and high end needle on side of carb. I am running 10% fuel with 20% oil. Master 18x8 prop. My problem is that I cannot get ity to run without the ni starter attached. It runs like a top with the ni starter attached, idle to full power. If I take it off, it dies instantly at idle as well as full power. I have tried fox miracle plug, OS type F and A5, plugs with the same results. Does anyone know why this is happening, and what to do to fix it?

Thanks
Voodoo

RE: 2 Stroke HELP!!!!!!
 

That sounds like a tough one and I may be totally be off base since I don't know the total situation with your engine.

How much time do you have on the engine? I have sometimes found it necessary to run a tank full or two during break-in before I could lean the engine enough to keep it running without the battery. I would also suspect that it will take about 3 gallons to complete a good break-in. I'd run several tanks on the ground, then fly with the engine slightly rich and not stay at one power setting the whole flight.

Another thought, many large engines require less oil than smaller engines. Volume, as the amount of fuel, is a cubic function, while area, the surface to be oiled, is a square function. As displacement goes up, the volume of fuel goes up faster than the inside surface area. All this means you need less oil in the fuel for the same lubrication than you do for a .46 or .61, for example. The bottom line is that you may need a lower oil fuel after the engine is broken in.

As for a plug, I would think the OS F or Fox Miracle would be fine.

RE: 2 Stroke HELP!!!!!!
 

Also, what you describe is an indication of a rich setting...having to have the plug artificially lit by the glow starter. Try going back to basics. Close off your high and low speed needle and hook up a fuel line to the carb. Open the LS needle until you can just blow through the line then open another 1/2 turn or so. Open the HS needle to around 2 1/2 turns for a base line and try that.

RE: 2 Stroke HELP!!!!!!
 

....I think your fuel is stale.

FBD. ;)

RE: 2 Stroke HELP!!!!!!
 

Hi!
Try max 5% nitro, 15-20% all syntetic oil and an Enya 3 glowplug.
Then use a 18x8 Menz wooden prop for best performance (Master A is the worst prop you can use, but ofcourse it doesn't have anything with how your engine idles or how to set the engine).
Are you sure the tank is mounted correctly? Not too high ? And fresh fuel?

RE: 2 Stroke HELP!!!!!!
 

Jaka....you might want to check the factory recommendations before you pull
numbers out of the air. My manual states that....

.... 10 or 15% nitro is fine for the engine
....a 16-8 prop for break-in

....and specifically not to use all synthetic oil in the engine !!

....it gives a specific glow plug recommendation....not a four stroke plug.

....Voodoo....get some fresh fuel for that engine. ;)

FBD. :D

RE: 2 Stroke HELP!!!!!!
 

Check the head bolts as they might be loose or the needle settings are too rich. A hot plug works best on big glow engines. Enya3 or OSF should work great but lean out the idle needle until the engine runs steady without the glowbattry connected.

RE: 2 Stroke HELP!!!!!!
 

Thanks for the help guys!! The head bolts are tight. As for the fuel I make my own. I work for a paint co. so I can get all materials free. Methanol is paint grade, Nitro is pure, same as any fuel manufacturer gets. I use straight castor for the oil. I am using the fuel in other engines that have no problem. As the end cap of the muffler came off in flight, I am awaiting a replacement before I can try setting the carb again.

Flyboy is it possible for you to scan the instructions and send to me? I did not get any with my engine.

Thanks again

Doug

RE: 2 Stroke HELP!!!!!!
 

Sure can....PM me your e-mail address. ;)

RE: 2 Stroke HELP!!!!!!
 

Voodoo....do not use an Enya 3 glow plug.....way too hot.

There is something wrong with your fuel. When you remove the glow, the engine quits.
It will not sustain the catalytic reation own it's own....

....buy a can of good store bought fuel and try it.....castor blend is fine.

I'll get that scanning done today. ;)

FBD.

RE: 2 Stroke HELP!!!!!!
 

Hi!
Enya 3 is not a "four-stroke " plug!

But it sounds to me that you haven't set the engine...Have you adjusted the high speed needle?

RE: 2 Stroke HELP!!!!!!
 

I agree with this although fuel and plugs is consideration, sounds like the engine is way off.

RE: 2 Stroke HELP!!!!!!
 

Well just wanted to let everyone know what I have done. I bought a gallon of 15% fuel. I tried to run the engine first with my home brew fuel with the same results. I then ran the storebought fuel and it ran good. Good idle, good transition and good top end. I then blended 1 part home brew and 1 part store bought fuel. I got a good idle, the transition was a little rich, but it would transition, and I got a great top end of a couple hundred more RPM's than just the store bought fuel.

Also I noticed that I am getting alot more oil from my fuel than the store bought fuel coming from the exhaust. I blended my fuel by weight, to 2 decimal points, using the Specific gravity of the 3 components, with 10% Nitro and 19% castor oil.

Since castor oil doesn't burn off like Synthetic will, is it OK to use a lower oil content when using straight castor?

Thanks

Doug

RE: 2 Stroke HELP!!!!!!
 

Hi!
Well over here in Sweden (and the rest of central Europe as well ) most flyers use 10-15% all syntetic oil.
I don't know any flier in our club (120members) that uses 20% castor oil anymore (well...I have to when I compete in Q-500 pylonracing , but that is because the rules so prescribe).


Of course you can use lower percenatges of castor oil as well, 15-16% is no problem as long you know how to set the engine and it's not cowled in.

RE: 2 Stroke HELP!!!!!!
 

I would think that the instructions for the engine should tell you the proper fuel mix. Just the fact that you are running the engine (assuming that it was new when you started the thread) will contribute to its running better and better as time goes on, regardless of the fuel mix (within reason).

A California college/university was using two of these engines to power their million dollar lifting body research model. It was on the Discovery Channel a few years ago. The engines ran fine in the video they shot. They were being used in a pusher configuration, which really separates good engines from bad, because of cooling issues.

Most folks mixing fuel at home mix by volume, though by weight is the most accurate way to do it, as you probably know. The problem is that most formulas bantered about regarding percentages of the components are usually express in volumetric units. That would appear to yield different percentages between volumetric and displacement gallons of mixed fuel. You probably know more about this than I. Whatcha think?


Ed Cregger

RE: 2 Stroke HELP!!!!!!
 

Large engines do not usually need 20% oil, that may be part of your problem. The store bought fuel likely had 17% or 18% oil. Some of the large Supertigres recommended only 9% oil.

I now recall haveing a similar problem when I ran out of fuel except for some old control line fuel with 25% castor oil. It ran but had problems with the transition, swithching to an Enya #3 plug did the trick.

RE: 2 Stroke HELP!!!!!!
 

The suggestion of low nitro and only synthetic oil probably won't help with the problem he is having.