My Magnum .52XLS is giving me a problem with mid range transition. It will idle all day long and transition right to full throttle, however when I'm flying if I stay at about 1/8 to just under 1/2 throttle for more then 10-15 seconds it's a toss up between dead stick, sputter and run or transition like it should. If the engine were on a sport plane I don't think I'd even notice the problem... for 3D flight the mid range SUCKS!!!!! It has no air leaks. So far I've tried lean/rich on both low and high, moved the tank position up and down and O.S. A3, #8, McCoy-59's and one fox plug... miracle plug I think. I'm running powermaster 15% swing an APC 12.25x3.75 somewhere around 12,500 to 13,000 depending on the weather. nothing so far has cured the problem for good, some day's I can make 1 or 2 flight's without a dead stick other day's it won't make 1 full flight. any ideas?? BTW if I stay out of the mid range and just go from idle to around half throttle/ full throttle it will run the tank dry... I even took it to 400 or so ft and glided it down at idle... dam thing transitioned right out several times... do one harrier for to long at 1/8 or so throttle ... you better be ready for a dead stick.


John

I am running my 52 with the same fuel, Thundr Bolt plug(R/C long), MS 11X7 prop. I would run the 12.25X3.75 execpt the prop would be under ground on my Global Lucky Stik. I had a problem with transition just like you are saying. The low end needle was set at 3/4 of a turn out. I leaned the low end a touch so I am about half way between 1/2 and 3/4 of a turn out. I can still pinch the fuel line and it will run for 4-5 seconds before it starts to change RPM.

I have found the needles to be very sensitive to adjustments. The low end, when changed from 3/4 to 1 full turn out will cause the engine to die when going form idle to full power. To me, it sounds like your low end is still a little rich. When you make changes make them in 1/16, 1/32 of a turn. I small adjustment can make big changes in the low end.

Dru.

Dru thanks for the advice... I've leaned the low end until it stumbles in transition(about 1/2 turn open), open it up just enough to allow transition to the highend and I still have the mid-range problem, it simply wont run any leaner on the low end than I've had it. you say you run the thunder bolt plug...maybe the plug the Magnum recommends is worth a try I tried thunderbolt plugs YEARS ago, didn't like the way my engines ran on them so I've just stuck with what I know... I'm also going to try a different prop[:@] I really hate to do this... that APC pulls the snot out of my plane and turns up real nice, It could be a load problem in the mid range though so I suppose it's worth a try.

Thanks
John

I had the same reaction when using the Hobby Shack brand plugs a long time ago. They would last a flight or two and not give good runs. If you can try the Enya #3 plug. It is not cheap but they do last a long time and will help with a rich running engine. I forgot to metion that I also wrapped the idle needle with teflon tape to help hold the position, mine is a little bit on he loose side.

Dru.

Dru Thanks again... I've never tried an enya plug... cost is not a big factor for me when it come to plugs, I'd pay $20 a plug IF my engine ran better with it and it had good longevity... I found out early on in this hobby cheap is not worth FRUSTRATION. If I don't get this 52 under control soon it's going in something that doesn't need good mid range performance... maybe I'll throw it on my scat cat I also had the loose fitting low end needle, I replaced the O ring with one out of a small hydraulic O ring kit we had at work... snugged it right up.


John

Are you guys running the same muffler combination? In other words, if both using the same muffler, have you removed the baffle, drilled out the exit hole, or? I have the XLS .52 myself and it is pretty new, so I am interested in this thread and the outcome. I'm thinking that the engine could be sensitive to tank pressure as well as having a very sensitive low end needle adjustment......

Ernie

Ernie good point... I'm running the stock muffler, stock exit hole baffle removed. I've tried it with the baffle in no difference[] I've also played with tank height, I could make it run worse but not better, right now the tank center is just a hair lower than the HS needle... I've also ran remote needle valve from day one, no air leaks so I don't think thats a problem.

John

I forgot to mention that I did drill out the baffle to a #20 sized drill and used copper colored high temp RTV to seal the muffler. The baffle helps with noise and tank pressure.

How long has the engine been running?? Mine had problems until I passed the one galon mark. I am now at 1 1/2 1 3/4 gallons and the power is up and the needle settings are staying put. There have been others that have the rich mid range you have and some don't, I would like to mic the carbs to see if it is a QA or a design problem

Dru.

P.S. Flying helicopters tought me that if I save $2.00 on a plug it could cost me $200.00 to rebuild my bird.

Does anyone know if the XLX .46 has the same touchy low end settings as the .52? I am considering owning a .46 for the $70 price tag.

Ernie

Dru, mine is getting close to the 2 gallon mark. If these last few little things don't clear up the mid range problem then it has to be the carb QC, if it were a bad design I would think they all would have the mid range problem.


Ernie several people run the 46's were I fly... some have problems some don't...tuning as far as i know has not been an issue. one had the high speed needle unscrew itself during flight... we never did find the needle. another leaked so bad around the HS needle it would not run right out of the box. in both cases Magnum sent replacement parts, the engines now run fine as far as I know. there has only been one 46xls that ran well right out of the box that I know of where I fly. I think at times magnum like all manufactures has some QA/QC issues. my 91rfs ran well right out of the box... it's has around 20 flights on it now with not ONE issue, the only thing I needed to do was adjust the valves.

John

The only problem I have had with my XLS .46 is with a pitts muffler. It has/had no fuel draw or tank pressure. I ended up puting a Pery osc. pump and have not had a problem since. The needles on the Magnums have a steep angle so they are sensitive as compared to O.S., Super Tigre, Enya, and others. A 1/4 turn on my O.S. and SUper Tigre are about equal to 1/16 of a turnon my Magnums. The .46 does have power.

Dru.

I had the same problem on my GMS .47 but only when vertical. Not a lot fun when practicing hovering. I did the same thing as bvldbuzzard and installed a perry VP30 pump. I've been using this setup for over two years now. Never a problem since.

Dave.

Jsn, for giggles, pull the idle needle out and see if there is a scratch, flat spot or other defect in the needle itself. It may be bent, placed off center in the threaded piece, scratched or just a bad grinding job. Mine runs well and so do others so that makes me think it is a case of QA/QC in the idle needle or the spray bar. You might have to use a loupe to see the needle better.

Dru.

I looked at the needle when I replaced the O ring... I'll take another Closer look though. one thing i didn't look at was the spray bar... it's worth a shot

John

Dru you may have just solved my problem... the needle has a few small dings right on the end, it also has a steep taper and is Blunt on the end, if memory serves me right it should be slightly rounded not square and flat... I'm I right on this? it's been a long time since i fooled with reshaping a low speed needle.


John

well I cleaned up the needle... I looked at it with a magnifying flashlight, it had a small flat spot right on the edge of the blunt end, took a VERY fine stone and honed it straight and 90 degrees to the shaft, I also polished the tapper. Just came in from test running it to see if I screwed it up... it seems that the mid range is Leaner!!!! before I when I did a pinch test when throttled in the mid range it would rev for 3 to 5 seconds before it started to sag, now it rev's for under or right at 2 seconds. Idle is still good, transition seems fine and the top end still screams. I won't know anything for sure until I fly it but it does look promising

Dru THANKS!!!!!!!
John

I hope I could help. The only reason I thought of it was that one of my old TT's had a flat side on it from the factory. I sent for a new one ond it was round.

I think the problem is just bad QC on the grinding of the low needles.


Dru.

My Mid range problem is solved... it must have been the small ding on the Low speed needle. I flew the motor 6 flights today, it dead sticked me one time, my fault I had the Idle set a bit to low. transition is great and now I can play all I want in the mid range throttle setting without it flaming out. just as a good test I spent several min putting around almost every flight at about 1/4 to 3/8 throttle without giving it a burp of full throttle to clear it out... it transitioned right out when I punched it. A week ago before I worked on the low speed needle this flight would have lasted about 20 to 30 SECONDS in low speed /midrange flight before it flamed out on it's own or died as it tried to give it throttle.


Thanks for all the help

John

That is good to hear. I am glad my long shot of an idea worked. One old timer told me long ago that the smallest thing will cause the biggest problem.

Now we need to get this info stored so we can let others that have problems with a rich mid range.

Dru.

Glad to see you figured out the problem!

I've run Magnum for years, and have yet to have to screw with the needles on any of them. I do know they are very sensitive on the low end, and are almost always waaaaay toooooo rich coming from the factory.

These motors are on sale for a measly $79.99 (April 23rd-27th). How can you go wrong, for that price!!??

Gary