Ok i'm starting to get really fed up with my trainers engine, in months I havnt had a successfull flight without a dead-stick or "bad sounding" engine necessitating an urgent landing.

It is a Magnum XL 52.

2 weeks ago I replaced ALL silicon tubing and secured them with small zipties (not too tight so I made sure I didnt cut the tubing...)
This was while trying to fix this problem, At that time I also found out that the needle valve (placed on the rear with a tube extender) outlet nipple was broken and letting air in.
The valve has now been moved forward and there is NO air in the tubing.

The plane always behaves perfectly on ground at startup etc.. but once in the air... things go wrong... it will "missfire" (not sure if its that but it hickups) or sounds very wet.. or just cuts out, on any throttle possition.

Today we started to work out that when we gave it full throttle... and someone picked up the plane, shook it.. moved it arround all axes, it would cut.

I'm getting seriously fed up and close to binning it and buying OS.
As its had a few "begginers landings" i'm wondering if its just taken one to many bashings..?

but where else can I look?

You might want to check the clunk in the fuel tank. Be sure it can move freely inside the tank.

checked and yes it can.

It's really a shame you have chosen this engine for a trainer. This not a trainer engine, but a performance engine that requires some skill in set up. One thing you can do is replace it with a more suitable engine (Magnum 46 XLS, for example) and come back to this engine for a future project that can benefit from the additional power at a time when you are more comfortable with running engines. You haven't said what prop, fuel, glow plug you are using or if the engine is new or fully broken in. You can start trouble shooting glow plug, fuel, etc now, but I can sense your frustration with it. You want to be flying, not fussing!

Another possibility is that you have a little speck of dirt in the needle valve from the hard landing. When you replaced the fuel tubing did you also replace the tubing in the tank? How fresh is the fuel you're using?

"You want to be flying, not fussing! "

Amen to that! IN my 20 years plus I fussed with Super Tigers and one K&B. I never had a problem with OS..., ever. I only fly gas and electric now, but if I would go back to nitro (.40 size) I would go back to a OS FX...

Some people like to fuss with powerplants, and love the challenge of getting one good run out of 10, and become experts in landing all over the place. As long as you are having fun this way, it is OK, go for it.
Me, I loved to run one fuel tank at home (on a new motor), go to the fled, and break the thing in in flight. I really loved those OS 40/46...

Good luck and remember, life is short, and out time at the field is very very short, use wisely:-)

Gerry

When you picked it up and shook it, were you pointing the nose skywards? If so, and the engine stops, you may be running the engine too lean. Richen it up a 1/4 turn to the left - or a couple of hundred revs below max, and give it a go. Whatever it is, I hope you find the problem, nothing worse than an unrealiable engine to unsettle your nerves when flying.

Ok, yes the engine is broken in. its 10% nitro Lube fuel i'm using with a 11x6 rprop currently but it was an 11x7.

I have flown F3F gliders for many years but moved to spain where there is not enough wind or hills to warrant gliding, so i've moved over to glow planes....
I got 52 speed engine as I knew it would take me very little time to learn to land on the runway and control the engine etc as the actual "flying" is not an issue.

Yes I changed the fuel tubing to the clunk as well.. it is ALL new.

Yes it was vertical when it cut out. The guy there suggested it could be due to starvation of fuel.

There is no spunge padding for the tank, could this cause problems?

I am going to try taking the whole tank system from another plane and plumbing it into this engine so I can proove wether the problem is in the tank section or motor section........

Check your tank stopper to ensure it is sealed... You can pressurize your tank a little and hold it under water and look for bubbles but usually if it's tight enougn you can't spin the stopper.

You mentioned you found the needle valve "broken". How exactly was it broken? Over tightened and stripped, tip broken off, rubber O-ring broken? If the engine was abused in anyway you may never get this thing to run right without extensive repair that may as well constitute a new engine purchace.

I for one have never had an engine damaged by a crash or hard landing but I suppose if you landed on the needle valve assembly it could be part of your problem. Also if you sucked dirt down into the crankcase and ran the engine without disassembly and cleaning this can cause reliability issues as well.

the damage was caused to the "extender" system for mounting the needle valve farther away from the prop.

The outlet nipple was slightly snapped and so letting air in..

I fixed this my moving the needle valve to the frontal possition beside the carb.

Some Magnum engines do have problems. You will do well with an O.S.

Iam currently rebuilding the fuel tank and pickup system again... with new clunks (from another retired plane which never had problems..) new fuel tubing (again)
and will padden the tank with foam.

if this does not work, on tuesday (pay day) its an os 46ax for me!!

ok some pics..

first shows the front of the engine.
There was a LOT of fuel escaping from here after I took the coweling off the plane. The cowel inside was totaly soaked with fuel.
Is this normal?

the last 2 show the needle valve problem and solution, in the last photo you can see where the threaded section of the nipple is still inside and where the nipple broke off.

Another suggestion - check the pressure nipple on your muffler for being clogged. That has caused engines to go lean in flight and nose up on the ground even if the needle is set rich.

I thought the 52 XLS had the blue anodized head on it, are you sure that's not the magnum .46xls as i've never seen a .52 with that head on it.

You haven't made any mention of your low speed needle. Magnums tend to be very sensitive to the low speed needle. You say the engine behaves on the ground, but don't specifically say what that really means. To check your low speed needle setting, let the plane idle at its lowest reliable idle for at least 30 seconds. Then punch the throttle to full. It should transition smoothly without hesitation. If it sputters and dies, the low speed needle is probably set too lean. If it hesitates and then goes to full throttle, its probably too rich.

If you adjust the low speed needle, make the adjustments in 1/8 turn increments or less. Then reset your high speed needle again before checking the low speed needle again. If it engine doesn't improve after a full turn on the low speed needle, go back to the original setting and adjust it in the opposite direction.

Another thing to check is to completely disassemble the carb to ensure all the fuel passages are clean and clear. Make sure the spray bar isn't varnished. Its amazing how a very small speck of plastic, silcone, or dirt will affect the mixture settings. Dissassembly and cleaning only takes a few minutes.

Finally, I'm confused by the pictures. You had a remote needle set up on the back of the engine, along with the needle mounted on the carb? Or was there simply a plug installed in the carb where the normal needle valve is now installed? If you had two needles in the flow path, you were probably creating too much resistance to flow for the engine to properly draw fuel. If you had the forward needle turned out far enough to preven this, there was probably air leaking in around it.

Brad

box says it is and the other side has 52 etched on it

OK, it seems weird that even at Global Hobby in the PARTS section for the .52 XLS it only shows the Blue head, was this engine brand new or did someone change things on this engine? could be part of your problems.

Hi!
The ASP engines are very fine engines...and powerful too.
It sounds to me that you haven't set the needles correctly. When you hold the nose of the plane straight up you should set the high speed needle at max rpm and then back off a couple of hundred rpm...this you can hear! No tach necessary.

Seeing your picture how the engine is mounted I can understand that you have trouble. The engine seems to be mounted too high compared to the tank. The best mounting position is to mount the engine on its side so that the carb center comes in in line with the tank when the plane sits horizontal. This is vital for good engine performance.

The ASP is a powerful engine and can swing a fairly large prop like a 12x6 APC without trouble . This is in fact the prop size to use even for the ASP .40 in a high wing trainer.

The ASP.40 has 2 head shims (believe the .52 has the same). If you run low nitro contents like 5% you can remove one of the head shims for better performance.
The engine also runs better with the high speed needle mounted close to the carb.
Tanks size: 10oz preferable set up with Uni-flow (Two clunks).
Glow plug: Several ...but Nova-Rossi 4, Rossi 4 OS 8 and Enya 3 and 4 are good ones

LoL....why didn't you just remove the rear needle assembly all togehter ?

well..you can't blame it on the engine just becuase...you don't know how to tune it.

I don't have problems with .46 or the .52 magnums

well, have you replace the glow plug that you used to break the engine with at least?

Did you wrap the fuel tank with soft foam to prevent foming cuazing bubbles therefore cuasing you to get hot and die.

It just depends. I can't be sure becuase it's a bit tough to tune an engine over the net.lmao.
Mostly likely I'd adjust the Low speed from the symtoms you're discribing.

In other words...it might be too lean. it runs fine on the stand or ground..but you need to richen it up
to compensate.
Therefore the lowend will get a little slugish..so you might need to adjsut it a tad.

If you let the enigne idle for a little while with the modle on the ground...you have to clear out the oil in the muffuler.
if you let off from WOT then to a slower throttle setting...this to will build up oil in the muffuler...therefore causing a slugish excelleration.

2 strokes are very easy to operate but are suscebtable to dirt,are you using an inline fuel filter?it could be clogged,also that carb looks awful big for a 52 could be causing a fuel draw problem unless you are using a pump or muffler pressure.also bkdavy suggestions as to the needle valve are also correct.have you tried running on a test stand?

I still have my magnum 52 and so does onother guy at the field. We decided to keep 'em 'cause we don't know anybody we don't like to give 'em to. [:'(] my low end needle can be seen rotating while the engine runs. locktite did no good at all.
get an OS 46 and have yourself some fun at the feild for a change.

I'm not sure what is going on but I don't think that you have a stock 52 XLS. Like posted above, wrong head.

Send them to me...I'll take them..both of them and all the magnums or non OS engines you have too.
I have teflon tape or spare O rings somewhere.lol

Did you send your mag's in then to get fixed? They do have a 3 year warranty. The magnum .52 is not a trainer engine and the 11x7 prop he is using is way too much load, this engine likes high RPM. I guess if you want a nice easy begginers engine then get the OS, if you don't mind breaking an engine in a little bit longer and actually doing some tuning then get the Mag, ST, GMS, etc.

PS. OzMo please give me some tips on how to pis$ you off so i can get your .52's first.