WILDCRASHWILLY

I would like opinions on an engine switch I'm about to perform. I have some experience with the Saito four strokes but not the magnum four strokes. I have numerous Magnum two strokes all perform excellent except a 52 that I have. I plan to replace it with a comparable powered Magnum four stroke They are letting me pay the difference and exchanging engines for me. My question is, is the RFS 70 comparable or should I consider replacing it with the 91? I also, need to keep in mind prop shaft lengths as the 52 is mounted back as far as it will go. It has a 1/16 inch clearence between the spinner back plate and the front of the fuse cowl ring housing. The fuse does not have a removable cowl the engine is mounted through the opening in the top of the plane. The plane is a Hots built from RCM plans.

Thanks for any info you can share on this subject.

Cyberwolf

My Feedback: (4)

Whats wrong with the 52 XLS .
I can share a couple things that I did to mine to get it to run .
1. I changed the carb to a OS fx 46
2. Make sure you run a gasket between the muffler and the engine .Honest this is a biggy !
3.Break it in with a little prop I was told by the Magnum techs to use a 10x6 untill it was fully broke in .I now use a 12x4 lots of power and runs fine .

As far as the length of the engines you can go to tower or hobby people and get the specs .But I think your going to find the 4 strokes are longer.

WILDCRASHWILLY

I run several Magnums in the 46 range and they have been perfect. The 52 has given me some midrange problems though. At times it has run good and at times poor transition. Now it does seem to make some bearing noise as well. I sent it to Global, I don't know what they found but they left me a voice mail stating they were going to send me a new engine or I could pay the diff and go with a four stroke as I had mentioned in a letter I sent them. I decided to go with the four stroke. I have to call them today and let them know.

asmund

then go for the 91. The 70 and 91 is of almost the same weight and physical size, if its too much power, throttle back, and you`ll have a more suited engine for coming planes. they tend to grow bigger and bigger as time goes

wcmorrison

My Feedback: (2)

The Maggie 91 4C is a lot more powerful than maggie 52 4C. The Maggie 70 is probably closer to the power range of the XLS 52. Like man said, I'd go for the 91 -- more engine!

Cheers,

Chip

WILDCRASHWILLY

Thanks for the advice guys, HAVE DONE. The Magnum service center is hard to beat IMHO. They took care of my problems with absolutely NO PROBLEMS!!!

Ed_Moorman

My Feedback: (1)

I own all three engines, the .52XLS and the .70 & .91 4-strokes. The .52 is a powerful, high speed engine. The 4-strokes both run great. The .91 is only an ounce or so heavier than the .70. I use the 4-strokes in scale plane and had the .70 in a sea plane. They have the grunt to turn a large prop, 13-6 for the .70 and a 14-6 for the .91, but for speed, you'll want the .52 XLS.

I also have Saito 4-strokes and I don't see much difference between the Saito .72 and the Mag .70 except the weight. Saitos are known for their lightness.

The .52 4-stroke would be nowhere near the power of the .52 2-stroke, but it is a great running, small 4-stroke. A buddy and I have a pair of .52 4-strokes in a scale twin and have never had an in flight failure.

fjbfl

Hi fellow members! I have a question that I hope someone can answer it?

I think I have a magnum plain Jane 46 engine? The only thing that was marked on the engine was
plate with the markings "M-46", and I am assuming the "M" stands for Magnum.

The Low speed Carb needle arrangement is rather unusual, in that to remove it, you have to
disassemble the whole thing, as the needle screws out from inside the carb. not from the outside
like most low end needle carbs.

My problem is that the needle works it way out when the engine is running. I tried to find a
replacement "O" ring for it, but can't find one.

Any suggestions?

Campgems

I'm no expert here, but I have two Magnum four strokes, a 52 and a 70. The 52 is just getting broke in, about 1/2 gal through it and it got it's first valve adjustment tonight. I am switching fuel also at this point. I used Omega 10% with 5 oz of castor added for break in. It ran good on the top, but I haven't got it to idle down well. My instructor pumped in a tank of his 15% today and what a difference. I'll see if I can get the idle down tomorow.

The 70 is a new engine with only one tank through it. I'll use the castor rich fuel for break in on it also, then to the 15%. I picked this one up to replace the 52 on my Ruperts Dad. I had to ad around 8 oz of lead to balance that engine out, and, gee whiz the 70 weighs just about 8 0z more than the 52.

Both engines are long. The 52 is 5 1/4" from the firewall to the face of the prop thrust washer, this is using the DuBro 4 stroke engine mount which adds a bit to the length. The 70 is the same length, but I wish I had given it another 1/8" or so because I couldn't use a lock washer on the mount to firewall screw behind the needle valve.

I'm just getting back into the hobby after 30 years and I am realy impressed with these two engines. Mount them up, fuel up and hook up the glow driver and hit them with the starter. Both fired up as soon as the fuel hit the carb and both ran quite well without any adjustments. Not the bad old days of flipping a prop for a half hour to get it running.

Don

Flyboy Dave

My Feedback: (21)

fjbfl ....

....your low speed screw is moving because of vibration. Balance the prop
spinner and backplate. Once you have the low speed adjusted perfectly (just a tad
rich) you can use a small amount of blue Lock-Tite applied with a toothpick to the
low speed screw threads on the outside to help hold it. A small amount of the thread
locker will wick into the threads and help hold it.

The correct answer is, of course, to replace the weak o-ring, and get everything
balanced, so the screw won't turn on it's own.

FBD.

WILDCRASHWILLY

ED

I went with the 70 four stroke because I felt it would be close in power to the 52 2 stroke, but mainly because I was afraid I would have a physical room problem with the Hots. I had built the engine compartment around the 52 XLS and was afraid the 91 would not fit since the 52 was a tight fit. I have modified the rudder and elevator tail feathers to make it more responsive as a fun fly plane so I'm not necessarily interested in speed. I do want it to have good pull out from a hover and harrier though. I should receive the engine Friday.

BTW, I see your connected to RCREPORT. I just dropped FlYRC and bought a two subscription to RCREPORT!! I read a friends and am looking forward to my first issue.