boosted180

My Feedback: (8)

hi. i have a magnum .46 2 stroke that keeps on quitting after about 3-5 mintues of flying. i'm absolutely positive that i'm NOT running too lean. in fact on one of my flights i richened it up to the point where it barely had power to fly (just to make sure), and still it quit on my after about 3 minutes. after landing, the engine was hot! i dont have a temp gauge, but the muffler was too hot to touch. what could be causing my problems?

i had a magnum .52 that ran really good for about 2 months, then did the exact same thing. in fact i've sent it back to magnum but they are still insisting that i was running it too lean and told me that it's not a warranty type of problem. am i doing something wrong or are these engines just crappy quality?

thanx,
brian

RC-Captain

Yes and they don't like alot of nitro. So how much are you using and what kind of fuel ?

Rudeboy

Engines just don't start "running hot" suddely after two months without problems...

I'd start looking elsewhere before blaming the engine. Check out your fuel system... and make sure your tank is properly isolated, as a lot of "engine suddenly dies for no reason" scenarios are caused by fuel foaming.
Take a look at your glow plug. Try a new one and see how it does on that.

Magnums may not be top of the line quality... but they sure aren't "crap" either...

tIANci

What do you mean by you are running not too lean? Have you tached it? Also, the low end does play a role on the temp, this is my experience with many 46 sized engines and actually most engines. If the low end is lean somehow the engine seems to over heat. Check the low end out.

boosted180

My Feedback: (8)

i'm gonna check out my fuel tank and lines today and will put more foam around the tank to isolate it from vibrations. i'm using 15% nitro powermaster fuel, thunderbolt idle bar plugs. i'll also try to richen up the low end a bit and see if that helps.

i wasnt trying to imply that magnum engines are crap (although i've heard this from quite a few guys that fly at my local field), i'm just trying to figure out what's going on.

like i said, my first magnum was great. the power was phenomenal, it hand starts almost every time, and overall ran great. it's just that it started overheating, dying, and killing plugs after about 3 months then things just kept on getting worse until it wouldnt run anymroe. if it was something on my part, i'd like to find out so i can prevent it with this engine also.

brian

BillS

Reasonable questions to ask yourself during the troubleshooting process.
1. Does it run OK on the bench?
2. Is the carb fuel inlet clean?
3. Is the low end over riding the top end?

Bill

Rupurt

What prop are you running? Is the oil coming out of the exhaust "clean" ?

boosted180

My Feedback: (8)

the oil coming out of the exhaust is clean. the engine has been really erratic, one day it'll be fine and the next i'd have problems. the last time i ran it, even while on the ground, i can hear a noticable decrease in speed after it gets full throttle for a few seconds. when it's in the air, this is even more obvious when i give it full throttle for uplines. then the engine would just hesitate real bad, or just dye after a few seconds of full throttle and i'd have to dead stick it. i thought i was running it too lean so i back out the needle valve to get it as rich as i could (barely enough power to fly), but still the same problem.

the carb fuel inlet looks like it's got some fuel around it but this is normal, isnt it? other than that, it's clean. there is no leak anywhere on the engine or in the lines as far as i can tell.

one thing i noticed was that there were tiny air bubbles from the tank running to the carb. i think this may be the fuel foaming and that's why i'm gonna try to insulate the tank.

i'm running an 11x5 prop.

what do you mean by "the low end overridding the top end"?

thanx.

Rupurt

Definitely sounds like it's still running lean. Check your clunk isn't to close to the back of the tank.

Flypaper 2

Bubbles in the line is a definite no-no. Absolutely will make it run lean. Could be a pinhole in one of the fuel lines. I'd replace the clunk line and the line between the tank and needle valve. Make sure the tank isn't touching a bulkhead or fuse side.

BillS

On most engines the low speed needle can be leaned to the point where the top end needle setting will not be reliable. The friction of the ‘O’ ring in the carburetor holds the low speed setting in place. While bench testing (highly advisable) I have seen the low speed needle vibrate lean messing everything up.

Suggest you pull the engine and put it on the bench until the problem is found otherwise it will take forever. Attempting to trouble shoot difficult problems in the airframe is dangerous to the health of the airplane. But … it’s yours not mine.

Bill

blw

My Feedback: (3)

What glowplug does Magnum call for? Do you have an OS F plug to try out? It is pretty much the standard for 4 strokes. The OS 8 is the standard for 2 strokes. You can't go wrong by substituting those plugs in this situation. That plug with an idle bar may be your problem (along with fuel line bubbles) if the manual doesn't specifically call for them. Is there a reason for using the Thunderbolt plugs?

I tend to disagree with the statement that Magnums aren't made to a high quality. I agree that they don't spend much on the finish of the outside, but they are normally powerful engines with chromed liners. Some are quite powerful, as are some ASP engines from the same plant in China. Evolutions are high quality engines (I have 2 of those) and they are also from the same plant. I think that some people don't think Magnums are good enough because they don't have the OS name on them.

huey-pilot

My Feedback: (17)

I had a similar problem with a ST 91 and OS .15, they would quit in the air after a few minutes of running. It turned out to be bad fuel, the fuel had become contaminated probably from pumping unused fuel from the airplane tanks back into my fuel jug. After I switched to a new gallon of fuel I haven't had anymore problems.

boosted180

My Feedback: (8)

problem solved! turns out that there was a tiny leak in my fuel line which was causing the bubbles (and causing the engine to lean out). i replaced the line, took apart my tank anyway to see if there's any other problems, insulated it with more foam padding, richened up the low end just a tad bit and it ran flawlessly today!

after each run, i used my high tech temp measuring device, my hand, to see how hot the engine was and it was very cool. i can easily keep my hand on the muffler w/o it getting uncomfortable. when it was overheating my last time out, i burned myself my just touching the muffler for a fraction of a second.

now i can finally get down to business with trimming her out.

by the way the thunderbolt idle bar plugs are great plugs, esp if you run an inverted engine. the os#8, at least in my experience got loaded up with fuel while going out to the runway and would occassionally quit. i use it in my magic extra which has an upright engine and it runs fine.

also, billS, you made a good point about the low end vibrating lean causing an unreliable top end. i think this is what may have happened on my .52. i'll keep an eye out for this on my .46.

thanx!

brian