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Magnum Engines XL 91 RFS Blue R/C 4-Stroke Engine

Availability: In stock

$189.99

No. 210868

OR

Quick Overview

This is a Magnum XL .91RFS R/C 4-Stroke Engine. The XL .91RFS is a single cylinder, four-stroke engine incorporating an aluminum piston, iron ring and steel sleeve for long life and high power output. A dual-needle valve carburetor for precise fuel/airflow metering is standard.

Magnum Engines XL 91 RFS Blue R/C 4-Stroke Engine

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User's Guide (259.9 KB)This is the User's Guide for the Magnum XL .91RFS Engine

Details

Magnum XL .91RFS

R/C 4-Stroke Engine

This is a Magnum XL .91RFS R/C 4-Stroke Engine. The XL .91RFS is a single cylinder, four-stroke engine incorporating an aluminum piston, iron ring and steel sleeve for long life and high power output. A dual-needle valve carburetor for precise fuel/airflow metering is standard. The engine features a dual-ball bearing-supported crankshaft and camshaft, dual bushing-supported connecting rod, and a high-flow muffler for more power and reduced noise. Your Magnum XL RFS series engine was designed by expert engineers and built by master craftsmen using only the highest quality materials and CNC machinery. These qualities provide the long life and dependability you have come to expect from an engine of this caliber.

Magnum has been bringing you high performance engines at an affordable price for more than 20 years! During that time the line has grown and expanded to offer a full line of 4-stroke and 2-stroke engines. And, all are made from the finest materials on the latest machinery. Plus, you get the added security of a full one-year warranty that protects you from any manufacturing defects and or premature wear (crash damage not covered). For reliability, high quality, and performance the choice is MAGNUM!

Features:

• Ringed Piston Design for Long Life and High Power

• Aluminum Piston, Iron Ring and Steel Sleeve

• Rear-Updraft, Dual Needle Carburetor

• Crankcase Gas Recirculating System - Improved Lubrication and Cleaner Model!

• Choke Valve and Lever

• High-Flow Quiet Muffler

• Dual Ball Bearing-Supported Crankshaft and Camshaft

• Dual Bushing-Supported Connecting Rod

• Blue Rocker Valve Cover

• Safety Propeller Nut

Specifications:

• Displacement: 14.95cc

• Bore: 27.7mm

• Stroke: 24.8mm

• Practical RPM: 2,000 to 11,000

• Weight with Muffler: 22.4oz

• Muffler Thread Size: M11 x 0.75mm

• Crankshaft Thread Size: 5/16 - 24

• Recommend Propeller Size: 14 x 6 (Break-In)

*Requires glow plug, fuel, propeller and support equipment. We recommend using 15% ~ 20% Nitro Methane Fuel with 16% ~ 18% Castor Oil/Synthetic Oil Blend Lubricant. We recommend using a hot heat-range glow plug designed for 4-stroke engines, such as Thunderbolt HP, O.S. Type F or Fox Miracle Plug. Propeller size will vary based on many factors. We recommend a 14 x 6 propeller for break-in.

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Additional Information

SKU 210868
Manufacturer Magnum Engines
Mfr Part Number XL91RFS-BL
Video No

Customer Reviews

1st one great, 2nd one not so great Review by At6 Flyer
Rating
First 91 awesome performance. Installed it in my Top Flite P47 and after three seasons runs like new. Second 91 not so good. I installed it in a Top Flite AT6. I broke it in as manual recommended using 10% fuel containing castor oil, Omega brand. Just started my second season and engine threw a rod. At least the plane was on the ground. OBTW I'm out of the warranty period.
(Posted on 5/26/14)
engine repair Review by airman10
Rating
I got my engine back from repair ran better than when out of the box and really quick service too. (Posted on 4/26/14)
so far runs great one little issue` Review by Tripacer
Rating
got mine up and running today for the first time in 50 years of modeling i followed the instructions on how to break it in even went and bought a NEW gallon of fuel set up as per instructions fired right up was WAY to Rich (would quit if you pulled plug wire off) leaned it out till the HIGH SPEED NEEDLE Bottomed out but at least you could pull the wires off and it would stay running ran a whole tank through (10 OZ) decided to figure out why it would run so rich with the HS needle seated took all apart and came to the conclusion the Needle was BENT and would not screw all the way down with out binding borrowed one out of my Magnum 46 2 stroke and now after 3 tanks i can adjust the needle all the way in or out and i think its time to go fly this beast
im giving it a 3 star for the bent needle have sent an email to there Service dept will see how good the service is should be a slam dunk just replace needle (Posted on 4/19/14)
breaking in Review by airman10
Rating
I was breaking in a new engine had ran a tank full though it and when almost through second tank it engine made loud noise and quit threw a rod.I have one with many hours on it.I think it was defective,it back under warranty (Posted on 3/11/14)
Lack of parts availbility Review by Single stick
Rating
Michel, our apologies for out of stock parts. Please know the crankshaft is now in stock. Matt


91 magnum in super skybolt .Flies great, engine all you need,smooth and steady.. Less than 2 hrs. running time suddenly stops . Remove engine from plane and remove back plate.. Crankshaft pin sheered off as if cut with a laser! 13 month old engineso no warranty. Tried to obtain a replacement part with no luck.that was 4 months ago.. now its December and still no parts..Stick with Saito and O.S. . Mike Melendy, Blue Max R/C flying Club (Posted on 12/2/13)
most reliable engine Review by tom
Rating
I have about 8 flights only on this Magnum 91 FS but it has never quit in the air or in idle at taxi in or out. This is m ore than I can say for my Saitos and OS 4 cycle engines. I also have 2 Magnum 52 4 cycles and the are the same for starting and for reliabilty. (Posted on 11/29/13)
Crankshaft problems Review by Pilots
Rating
This is my second engine. The crankshaft broke on both after about 75, 10 minute flights.The first time I crashed my plane, the second time i was luckiy because I was still on the bench. the engine runs great but this is a dissappointing flaw. (Posted on 9/26/13)
91 magnum Review by butthole
Rating
nice engine for the money (Posted on 7/25/13)
First Glow Engine Review by x-electric
Rating
My first Magnum .91 would not run very well after break in. It didn't seem to respond to needle valve adjustments and the needle turned very hard. I removed the high speed needle valve and found some debris inside like chunks of o-ring but the o-rings looked fine. Cleaned everything out and then I could get it set up and it ran wonderfully :-). I have owned this engine for over a year now with no problems at all. Starts very easily. I use a starter motor without using the choke (much less messy). So I removed the choke lever as it just gets in the way. I have the engine mounted horizontally in a Great Planes Escapade 60 and have been flying this setup going on the second season now. Starts great, idles great, has plenty of power, and what a bargain! (Posted on 4/30/13)
First one Review by So far so good
Rating
I'm an OS guy but always am looking for a bargain. I have a lot of engines, including OS, YS, Super Tigre, Thunder Tiger, and a couple of mongrels. So far so good with my new Magnum 91. it started slobbering rich following the directions. I couldn't get it to hold on even using the Sullivan on board glow. it finally ran and held on at about 1 1/2 turns open on the main. Break-in was OK. It ran out a couple of tanks and it seems like it will be a strong runner. It even gave me a good smokey idle. The heat being on at high trim helped. Confidence is high,will report back after the maiden and a few other flights. I bought this on sale for $130! Now that's a bargain! (Posted on 1/15/13)
A great engine! Review by RON
Rating
I have a few Magnum engines, One of the Vegas store managers was a store manager, we were flying one day and I was using a different but one of the top brands of 4 strokes, It always gave me problems with the low end from flight to flight. He asked me to buy the 91, he wanted more flying info first handed, I bought it on sale and did the recommended break in exactly, He wanted to follow everything in the directions. I was flying a Global ultimate Bi-plane and the 46 that I had in it just wasn't getting it, I decided to install this engine in it, (It came out a little tail heavy anyway and this engine balanced it just right) I ran it pretty rich for a few days, we flew every morning. After just about half of a gallon I started leaning it out. Doing it as my 40 years in the hobby taught me. Nose in the air. I demand quick throttle response, smooth throttle response and good idle that I could depend on out of my engines
I fell in love with this engine, I had more power than the Ultimate needed but it was and still is fun. I don't remember when the first Hobby store opened in Las Vegas NV. but this is engine is still in service in the same Plane.

I now have a couple of 52 4-strokes and a few 2 stroke engines none of which I would part with. I don't pay the high price of some of the other engines, Hobby People prices it's engines so the every day flier can buy them and I do not or ever have seen a difference in Magnum in retrospect to the High cost engines. You can"t go wrong with this and the other Magnum engines.. Take the plunge, You'll be happy you did.
Ron in Navada. (Posted on 12/11/12)
Great engine at a great price Review by HPDriver
Rating
My first 4 stroke engine. Replaced a Super Tigre .75 in a Hangar 9 Spitfire MKII 60. Throttle arm on the same side so basically a drop in. Startled me by starting on the first flip. Starts and runs as good or better than any engine I have had in 50 years of model activity. Liked it so well I purchsed a Magnum RFS .52 for my Kaos .40. Same experience as the RFS .91. Usually one flip starts and flawless performance. Thank you Hobby People for great products at great prices. (Posted on 10/26/12)
Great !!!!!!! Review by Patrick
Rating
Patrick, thanks for the great comments. Matt

25 years in hobby and have spent alot of money on things that advertised quality and it turned out to be junk .., I have never had a motor that could hand start right out of the box. Very little adjusment and it has never missed a beat and pulls my aero works 300 much better than the "Junk" dle 20 I finally threw in garbage . (Posted on 8/6/12)
Great running hassle free performance Review by Mark
Rating
I have had several magnum 2 strokes over the years all were good performers. This is not my first 4 stroke but my first magnum 4 stroke. My 91RFS is in my hanger9 Fokker DVII and it runs great. Running 10 % with a 14x6 wood prop about 15 flights . Love the sound and performance. Can't beat how easy to operate these engines are.Would definitely recommend any of their engines. (Posted on 6/21/12)
Performance, Performance, Performance!! Review by Calebizsol
Rating
This engine is installed in a World Models 60 size P-51 mustang. I've ran about two gallons of fuel through it. Started with 10% Nitro and now I'm running 20% Nitro (Coolpower). The bird climbs like a banshee and is totally predictable and responsive on final approach. Never a dead stick!! Taxiing is a pleasure. I'm using a Saito Glow plug and a APC 14x6 prop. As a matter of fact, I just flew it an hour ago!! (Posted on 6/20/12)
Great engine. Review by Magum "MAN"
Rating
I have a fleet of Magnum's. 52's on Kayos's,70 on "SOPT ON " 50 ,,AT-6 , and now my new DirtyBirdy ,now have about 100flts. on it, Just one word "AWSOME",put fuel in it let warm up for a second or so, and fly, no need for all the adjusting, tach. etc. Do what you went to the field for. FLY Thats my story and I'M sticking to it. (Posted on 6/1/12)
Great Engine Review by Old Hoosier
Rating
Love the power and the sound! This my first 4 stroke engine. Wish I had gotten one years ago. This 91 is on my Big Stick 60. I have about 15 flights on it with the 91. No messing around, just start it, fly it, and enjoy.

I'll put a Magnum 4 stroke on my 81" Cub. Looking forward to flying it and listening to the neat sound of the 4 stroke. Quiet and powerful engine
(Posted on 2/24/12)
perfect Review by skyking
Rating
Had this engine on a senior telemaster with really big tires, weighting in around 12lbs. and flew like a champ. NEVER had a problem what so ever. Don't know how old the engine is, but its old. Locked up several years ago, taking apart and put back together with NO ajustments and run PERFECT. NEVER, EVER, would I buy another OS. (Posted on 11/20/11)
Solid Reliability Review by Rich
Rating
This is my second Magnum 4 stroke.The other is the .52 .
Broken in as the manual states,These are the most reliable engines I have ever had the pleasure to fly.The only time one didn't start was my fault,I had the throttle
servo reversed.It's a good thing it didn't start!! Great engines,never a single dead stick or difficulty.Grab one ,you will not be sorry ( : (Posted on 12/27/10)
Hard to beat Review by Dragonfire
Rating
I have several Magnum .91's. They never give me any stress.. Just prime, connect glow ignitor, and flip! You cant go wrong here! You want a stress free engine? Here it is.. (Posted on 12/11/10)
Runs great, good power and no dead slicks Review by Clyde G.
Rating
I am using two Magnum XL 91 RFS 4 strokes on my ASM A 26 Invader Bomber.
I have 31 flights on my plane without using onboard glow and no dead stick landings. Both engines start easy, have good power and sound great as twins. (Posted on 11/26/10)
Super deal Review by Rich
Rating
Running 15% cool power, 14X6 prop, have three in my planes, an Astro Hog, a Four Star 60, and J-3 Cub. Perfect low idle, transition, and all the power i need. I prime the engine, add my glow heater, and 1 or 2 back flips and it's running without any fuss. (Posted on 11/19/10)
Great price, bought 4, all reliable for me Review by Dalotel
Rating
One of the best idling and transitioning engines I've owned. Break in was easy. It runs great on a 14X6 prop, 15% cool power fuel. Using 3 of them presently, 1 in a Four Star 60, a vintage Astro Hog, and a J-3 Cub. I prime the engine and 1 or 2 back flips, it's running without any tinkering at all. (Posted on 11/19/10)
Not real happy with performance. Review by Dave
Rating
Dave, Please call the Magnum Service Center as I am sure we can help. The 91 has great reviews and many of our guys are flying. Its a great engine. When you call, please provide to our tech the glow plug type, engine mount location, and any other info you deem important. We look forward to helping you.


I recently purchased two Magnum XL 91s and they were not what I had expected from Magnum. I have about 10 Magnum engines in various sizes. I purchased the 91 4-stroke to replace an 80 4-stroke hoping it would have more power and speed. I mounted it on an airplane designed for a 46 2-stroke. Boy was I disappointed at the lack of power the 91 4-stroke had. I mounted the other on a Camel designed for a 61 2-stroke and again I was very disappointed at the power. I even flew the planes several more times to give the engines time to break in and still not very much power. I also tried different props to see if that helped but not much difference in performance.
I will still buy Magnum engines but not another 91 4-stroke. (Posted on 10/18/10)
Nice engine-Great people to work with at G/H. Review by Jim
Rating
The 91 is a very good engine, I would buy Magnum 4-strokes over any other brand because they run very well, and product support is A+. also this engine is very easy on fuel. (Posted on 10/18/10)
Nice engine, nice service Review by Matthew
Rating
I have to give credit to Global Services for servicing my XL 91. I flew this engine in a 60 size Mustang. It flew very nice; throttle response was quick and the power was awesome for loop, inverted fly, tight turn, high-g turns,...The idle was nice. It also had good power at low speed, and helped me land the P51 like a dream. Unfortunately, one day I was stupid enough to fly in a 33 mph cross wind and had a crash landing. The carb broke. I sent it to Global Services. After about a month, they returned the engine back to me, nicely clean, with a long list of parts that were replaced, and get this: AT NO COST! They even test ran my engine and gave me its data performance. Just ask Farrell at Global Services, and you´ll agree with me how nice they are.
I like this engine because it flies well and less costly than the O.S and Saito, which I was thinking about when switching from 2 stroke to 4 stroke. The sound is fantastic, almost like a motorcycle. You just broke in about 1 hr, adjust high/low, test fly (I did 3; they recommend 5), and that was all. After that, just add fuel (I used 15% Omega, the same fuel for my 2 stroke engines) and have a good time. At full throttle, the fly time is about 20-25 minutes. My fellow club members kept asking me to land because "man, you´re up there for quite awhile" (Posted on 8/30/10)
magnum 91 4 stroke Review by Jim
Rating
I have been using the .91 4 stroke magnum for over a year now, it has over 10 gallons of sig 10% fuel through it now and i have adjusted the valves once. It runs excellent, always starts even in 0 degree winter months. I have had absolutely no problems and i am extremly happy with it. I have ordered another .91 and another .70 4 stroke magnum. I plan on replacing all my engines with the Magnum 4 strokes over time. I have the .91 on a telemaster sr. and it is almost unlimited in power, I can even do outside loops with it. I lift off the ground in 10 foot or less. Happy, Happy, Happy (Posted on 8/30/10)
Runs like a well oiled clock Review by Ted
Rating
I am very impressed with the Magnum XL 91 RFS 4 Stroke Engine. It is was easy to start right out of the box. What really continues to impress me is that it continues to be easy to start as well. The idle is simply fantastic. It just stits there and idles it seems forever without any sign of wanting to quit. I never expected such performance in a .91 sized engine and at such a reasonable price. (Posted on 8/30/10)
Great Power and Great Price Review by Andy
Rating
Been running Magnum for 20 years. This is a great engine. Transition is good, low end and top end are reliable and engine just works. Great engine. (Posted on 8/26/10)

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