misterpanda

I recently ordered a new Magnum 91 4 Stroke (with the blue valve cover). Should be arriving shortly. This is my first foray into Magnum 4 strokes. Did I make a good purchase? Any tips or recommendations for this engine? I'm all ears.

Thanks a bunch in advance.

Misterpanda

jeffie8696

Hit and miss quality control, if you get a good one its a good deal.

NM2K

My Feedback: (14)

Is it your first four-stroke? Or is it your first Magnum four-stroke? If it is your first Magnum four-stroke, but you have had other brands, such as OS, Enya, YS, Thunder Tiger, you may be surprised at how much longer it takes to break-in than some of the other brands previously mentioned. Worry not. It doesn't take THAT much longer. Just hang in there with it and you will enjoy a good, solid engine.

Use a dab of castor oil in your fuel, if you can. Always run your four-stroke a tad richer than you would run a two-stroke and they will last a long, long time. Four-strokes are not as prone to quitting from running rich. Not to worry. I hope you enjoy your Magnum four-strokes as much as I have enjoyed mine.


Ed Cregger

jeffie8696

Just for fun, here is my Magnum 52. http://www.youtube.com/watch?v=MtBmcXQpUYk

misterpanda

This is my first Magnum 4 stroke. I'm currently running a 70 and a 52 Surpass by OS. Both run like clockwork and I enjoy them very much. Currently running full castor home brew with a touch of nitro (which is rather hard to come by around here). Wanted to try out a different brand of engine. As far as the predicted long break-in is concerned, that's ok by me. I enjoy running these little marvels of engineering, anyway. We'll see how she turns out. Thanks for the tips and light shed.

Misterpanda

wcmorrison

My Feedback: (2)

I have enjoyed my Magnum four strokes.  High Nitro is not necessary.  They do like some Castor and probably will tolerate all Castor oil very well.  Here in the States where Nitro is easy to get, I burn generally 10%.  I own Saitos, OS and YS too.  But I seem to run my good old Magnun more than the rest of them.

jeffie8696

Ihave been running 30% just for fun.

NM2K

My Feedback: (14)

Let me know how much fun it is when the extra nitro breaks the crankshaft and you have to change it.


Ed Cregger

jeffie8696

Just dont care.

1QwkSport2.5r

I cringe at the thought of using more than 10% nitro, let alone 30%.. I think all but one of my engines won't run well on more than 5%. I might even quit running nitro in some of them to save money.

I've never had a Magnum anything, but a buddy of mine has a few 2-strokes and 1 or 2 4-strokes and he has had good luck with them. One of his Magnum 4-strokes has 15 gallons or more on it and it still runs well. I'll probably never own one, but those that have the good ones like them.

TFF

My 91 has been chugging along for about 10 years. 2 airplanes and no special care; more like abuse.

NM2K

My Feedback: (14)

Do you remember a while back when some members of this forum began breaking crankshafts in their Magnum FS-91 engines when using higher nitro values? I'm not bad mouthing the engine. I have several of the various sizes myself. I just don't think that I would like to go to all of the trouble to break one in and then break it purposefully when I knew that higher nitro fuel would cause such a failure.

Jeffie's a big boy and can handle his problems himself. I would just hate to see someone else break a great running engine by reading about Jeffie's 30% nitro adventures and trying the same thing themselves, without having been warned of the consequences.


Ed Cregger

fiery

My Feedback: (2)

Use 5% nitro in ours, they run fine.

Save the 30% for the YS's.

mike109

G'day
Down here we don't see many Magnum engines these days but we do see lots of the ASP version which is essentially the same and comes from the same factory. Generally they are OK though the four strokes generally run better than the two strokes.

Some times we have had leaking valves - I had one on a 61FS and a friend one on a brand new 91 - but I fixed the 61 for a few dollars by buying a new head complete with valves and I fixed the 91 by using the old "toothpaste lap" trick. I suspect the valve or seat had some contaminant on it and a gentle clean with some tooth paste and she was good to go.

I'd say you will be pleased with your new 91 and as you are in the US of A, you can probably get reliable warranty service if you need it. Most of the ASP motors I have seen have been imported cheaply from Hong Kong so we just sort out any problems we find for our selves.

Oh yes, most of us run 10% nitro in them and some castor oil too.

Cheers

Mike in Oz

acdii

Been running 15% Wildcat in my engines and they all run really good.  Fuel recommendations is 15-20% in the manual for the Magnums.  It also states you can run 25% Nitro as long as you have 18% or higher oil content.  Both my Magnums, a 52 and 91 run really good. Both fire off on a back flip of the prop, my OS needs a starter whether its the first start of the day, or it just came in for a refuel.

NM2K

My Feedback: (14)

I just looked at your video. Wow! That sucker is moving right along. What size prop are you running? I already know that you're using 30% nitromethane in the fuel.


Ed Cregger

jeffie8696

I am using the MA black 11X7.5 prop, it seems to work really well with all my 50 size 4 strokes.
My buddy Joe reccomended it to me and it is a great choice for my application.
Iinstalled the 52 4S to slow the plane down from the Irvine 53 , 2S that caused it to flutter one day. Ilike it just fine now.

acdii

The APC 11X7 is even better then the MA. I ran the MA on my Kadet with the OS 52 FS, then switched to the APC and it flies even better.  I swapped out the OS for the Magnum 52 and the results are pretty much the same.  The MA has a bit more flex than the APC.

jeffie8696

My finger still hurts.

BAS

My Feedback: (28)

Just for info i have a Magnum 91 and a ASP 180 and use Wildcat Heli fuel 30% nitro 23 % oil . I have around 3 gallons thru the 180 and 5 gallons thru the 91 with 2% caster blend. Had no problems at all both run very smooth and idle is great.

jeffie8696

maybe the air in iowa makes the engines tolerate more nitro

1QwkSport2.5r

I always knew there was something about Iowa that was better than Minnesota...

acdii

So far the 91 is running good, needs more time on it, but that will have to wait, I dumbthumbed the plane it was on taking off in the wrong direction with low rates and folded the wing.   I also think the tank was too low because the fuel would drain back with the engine off, which is probably why I had issues with a dead stick.  

warshop

Hello all: I have acquired a couple of Magnum .91 4-stroke engines ( older ones, before the current blue hear series). I have one INVERTED in a plane. What is the best Glow-Plug for the Magnum .91 inverted. Also, which best prop size. I am using 13x8. Also, using 15% fuel.

Thanks for your replies and knowledge about this engine, for best running performance..........

BAS

My Feedback: (28)

Use a OS F plug or Ys Plug . I have used these two in all my 4 strokes for years and they last a long time. Prop sounds about right i have a newer 91 and i use a 14/8 but i run 30% nitro.