Hobie

I might just give up on the Magnum Engine I looked at reviews on it and there is allot of negative remarks . It would be a good excuse to put a bigger engine on my Hanger 9 Twist PNP and put the Evo. .46 NT on the Sig Kadet .40 LT .

BillS

I found a picture and she looks sparkling. Worth doing a Google search.

Bill

MinnFlyer

My Feedback: (4)

That is the throttle stop. It does two things - It keeps the throttle from opening too far, and it holds the throttle barrel in the carb body. Don't mess with it.

Hobie

OK I won't mess with it . I may not mess with this engine ever again . The stuborn side of me wants to make that engine run . The logical side of me says I have tried enough times to get the thing running and other pilots have had their share of problems with this engine also so give it up . If I give up I am not out anything since this was all given to me but I did want Larry to see everything fly just the way he had it . I do like the idea of getting a bigger engine for my Twist since most who have had the Twist for awhile go with a bigger engine then the Evolution .46 . This is my 2nd season with the Twist and I have flown it many many times so I think I am ready for more power . I still have done no 3D with it but I may try 3D with a bigger engine .

MinnFlyer

My Feedback: (4)

Here's something else to try.

See if you can move the carb back and forth.

If you can, losen the two screws that hold it on, press the carb down hard with your thumb, and while you're holding it down, re-tighten the screws.

Sport_Pilot

Bubbles are not necessarily air, they can be vaporized fuel. This can happen if say the fuel line comes close to the muffler and is warmed up then some of it flash's to vapor when it drops pressure across the remote needle. It can even happen if it does not come close to the muffler on a hot day.

woody12

I had a similar problem, with large bubbles and did all the tank stuff,only to find the air leak in the remote high end needle valve O ring.

Ricky Blade

from a recovering foamy fuel flyer. open the tank area and lightly wrap in soft foam rubber. isolate from the vibrations at all costs if you want to resolve your dilema. ricky

y2thomas2000

I used to have the same issue. I switched to Powermaster HELI fuel as it has an anti foaming additive. fixed the problem from vibration.

themorses2000

Make sure that your fuel tank is isolated from the fuselage...I had the same problem with Sig 4Star ARF...I created some space and installed foam to dampen out vibration...I also precision balanced the prop...Huge difference.

jhrdflemming

Hello, I found your advice and photos regarding the air in the lines very good. I am currently strugling with a TT 60 stalling in mid flight or at climb out (ouch). I think what I am seeing is bubles as in figure one. What kind of a problem does that indicate??

Hobie

I am not sure but I am amazed that you found this thread that is over 2 years old . I gave up on that Magnum engine 2 years ago and have never tried it on another plane ever since . Good luck .

Rod Bender

Could be vibration, how is your tank secured? Is your tank above\below carb centerline? have you checked ALL the fuel lines for pinholes\cracks? Is your stopper tight and not allowing any air in? How old is the fuel line?

Quigleywins

I read with intrest the thread only quickly but no one made the suggestion that the bubbles were in fact cavitation. that is because the fuel is being drawn to the spray bar by the low pressure in the venturie (below Atmospheric pressure). these bubbles appear and can be a problem to remore. In large engines I have found that to remove this problem First remove all filters amd examin there contence even if they were new the day before. Clean the water filters. Then start the impossible task of checking the joins which you did by replacing the fuel lines. In my entyre time on the road I only found that only twice this method not to work. In one case The injector was allowing cylindr pressure back into the fuel lines( in theory this is impossible so after a week of satisfactory operation we changed the old injectors back and yes the problem was with us once more) On the second occation we went to larger fuel lines which prevented the engine fuel sustem from cavitating. Now after all that dribble my suggestion is to look at the pressure pipe from the exhaust. the problem may be fixed by increasing this pressure Rember this motor has a problem and you may have to think out side the normal. My other suggestion would be to make sure that the presure in the fuel tank is not leaking. Take an air supply from a car wheel at low pressure say 4 lbs/sqins and run that into the fuel tank run the engine And see what happens. If this fixes the problemThe exhaust can be made longer , I also noted that the pickup point on the exhaust was at the end of the system I think there could be more pressure at the front of the exhaust system. Rember this motor has a problem and it may be in the design. But it is fixable never give up. Yours Paul T

loopdeeloop

My Feedback: (4)

That screw retains the rotating throttle barrel in the carb body. I've run a bunch of Magnum engines and they are my engine of choice because of cost, performance, and durability. After all, they are a clone of the O.S. Try loosening the clamp nut that holds the carburetor into the crankcase. Remove the carb and check the condition of the O-ring. Replace it if necessary and when you reinstall the carb, hold pressure on the carb (forcing it into the crankcase) while you tighten the nut. An air leak is possible in that area. And just so you know, one high speed needle setting from the manual is not the final setting. That is just a starting point. The low speed needle is inside the throttle barrel on the side where the servo linkage attaches. A leaky back cover gasket is also a possibility. Check it.

Steve Collins

My Feedback: (8)

After 8 years have passed, they have either solved their problem or chucked the engine. I doubt they are monitoring this thread.

JollyPopper

My Feedback: (6)

For anyone who stumbles onto this thread, I have read somewhere that just a drop or two of WD40 (I believe it was WD40) in a tank of fuel can diminish or eliminate foaming,

mashp39

My Feedback: (1)

Have you tried the WD-40?

JollyPopper

My Feedback: (6)

mashp39, if you were asking me if I had tried the WD40, the answer is "no". It is something I have read but never needed to check out, but it is maybe the easiest fix I have ever heard of if it works. If not, no harm done. If I had a foaming problem, I would certainly try it.

mashp39

My Feedback: (1)

I just reread this post and since there is not much chatter anymore at this site I thought I would just throw out a thought.What if you added the WD 40 to a new jug of fuel?The amount is open to discussion but would not this solve foaming in the first instance and and let us worry about something else?I have used Magnum engines in the past and air bubbles don't seem to be caused by any particular engine.I wonder if the original poster has read this recent discussion?

aspeed

I thought it was a couple drops of Armourall in the gallon. Never heard of the WD 40. it is mostly kerosene diesel fuel with a propellant. I have/had a light plane that vibrated a fair bit and the bubbles were very bad. The motor was not the problem, but the weak mounting and the plane itself. I just tossed the plane out. It did fly ok after in the air, as the bubbles went inboard. It was control line though. The OPs plane was a Something Extra, like a Twist which is a toothpick plane which could be shaking a lot. They are overengineered to be weak, I just added a doubler on mine. I like it otherwise, but the engineers should be ashamed of themselves, shot and p... on. Historical thread here. I bet things have changed, but maybe not. The motor may still be in the disappointment drawer for the wrong reason. Brittany Speers is now a senior citizen now. I guess at my age, everything looks good.

jaka

Hi!
In all my 42 years of flying R/C the problem with air in the fuel line has always been a leak in the tank somewhere,never foaming. Often has the problem with air bubbles been due to a leaking rubber stopper /or the brass tubing protruding it, which most tank manufaturers use, except Tettra.
Since I started using Tettra "Bubbleless" tanks 25 years ago, first in my pylon racing planes , then i my sport planes I have never had a tank issue.