Magnum XL70RFS 4-stroke engine review - RC Groups
Shop our Airplanes Products Drone Products Sales

Magnum XL70RFS 4-stroke engine review

Magnum's new XL.70RFS .70 4-stroke! This engine is a single cylinder, four stroke constructed with an aluminum piston, an iron ring and a steel cylinder sleeve. It also features ball bearings on the crankshaft and camshaft and a dual needle carburetor.

Article Thumbnail


Published Engine Specifications
Practical RPM:1,800 – 11,000
Weight w/Muffler:21.2 oz.
Manufacturer:Magnum by Global
Available From:Hobby People

First Impressions

The engine was adequately packed and had no damage. It came with some very good documentation including an operating manual, a maintenance sheet explaining valve settings, an exploded-view drawing with part numbers, a quick start guide, a decal sheet and a very detailed troubleshooting chart. The engine also had 2 allen wrenches for service. It did not include a feeler guage for setting the valves, any measurement data, or a glow plug.


There was not a measurement chart included with the engine so these are the measurements I made. Bear with me, here goes…

Crank threads:5/16-24
Case width (not including mount lugs):40mm
Overall case width (including mount lugs):57mm
Mounting hole width (center to center):50mm
Mounting hole (front to rear, center to center):21mm
Drive washer back to front mounting hole:55mm
Drive washer to tip of crank:36mm
Mounting hole diameter:4mm
Height (bottom of mount lug to valve cover):98mm
Bottom of mount lug to bottom of case:21mm
Drive washer to back plate:86mm
Drive washer to rear of carburetor:113mm
Drive washer to back of choke bracket:119mm


Check out the nipples in the intake and at the base of the cylinder just behind the cam cover in the photo above. These are connected together via a short piece of fuel line and make up the re-breathing crankcase vent. It expels excess oil from the nipple behind the cam cover and draws it into the intake to use it again. There are only positives to this arrangement. It provides it’s own “top end” lubricant, it’s eco-friendly and it helps keep your plane slime free.

The offset manifold allows the throttle arm to be a wee bit more ARF friendly...due to a lot of manufacturers pre-drilling throttle linkages for 2 strokes. This puts the arm right in line! No more bending horseshoe shapes in the throttle rod!

Magnum comparison pictures...XL.52RFS (left), XL.70RFS (center) and XL.91RFS (right)

Factory Recommendations

I broke in the engine per the instructions. Magnum recommends that a fuel with 10% nitro and a blend of 16% Castor/synthetic oil be utilized for break in. They also recommend a 13-6 prop for break in. I used a Master Airscrew 13-6 K series and an O.S. Type F glow plug.

After running 40 ounces of fuel through it, the engine remained trouble-free. I had to richen up the low speed needle only 1/8th of a turn to get a flawless transition. I then changed to the maximum nitro content in the form of 15% Cool Power with Byron’s Castor additive.

RPM Readings

The following RPM readings were taken at 300 RPM below absolute peak.

Master Airscrew K series12-810,500
same14-6 (largest recommended)8,800
same14-4W(Idle) 1,900

Flight Testing

For detailed flight coverage, watch RC Power for an upcoming review of the Global Decathlon, including flight testing with this engine!

Hear Her Purrrrr....



The Good Stuff

  • Great power.
  • Value priced.
  • Centered carburetor choke.
  • Maintains it’s needle settings.

The Not So Good Stuff

  • No printed dimensions and measurements.

The Magnum XL.70RFS is one sweet engine. All throughout the testing, it never gave me so much as a hiccup! It’s ruggedly built, trouble free, strong and inexpensive. This is a no brainer. An engine that delivers premium performance at a value price needs your attention! It has a rapid and seamless transition, even when swinging the big flat blade 3D props. It’ll idle down to 1,900 RPM, reliably. As a matter of fact, The RPM numbers for the MA 13-6 AND the APC 14-4W props match my O.S. FS-70 S2 exactly!!!

I would not hesitate to recommend this engine to anyone.

Thread Tools
May 30, 2004, 11:06 AM
Carrying a lot of weight!
therotund1's Avatar
If anyone has any questions or wants to know about any details that I may have missed, I'll do my best to get them answered.

A special thank you to Don Sims for shooting the video on this engine.

Dave Huff
Oct 13, 2004, 03:17 PM
Registered User
What is the dimension from the shaft centerline to the top of the valve cover? Needed to see if the engine will fit within a cowling.
Oct 13, 2004, 03:54 PM
Carrying a lot of weight!
therotund1's Avatar
Pete, I'm measuring 98mm from the centerline of the crank to the top of the valve cover.

I just happened to be mounting another one of these on a different plane... Good timing huh???

Oct 13, 2004, 04:25 PM
Registered User

Shaft to Head Dimension

Very timely! One gets lucky once in a while.


Nov 08, 2004, 08:13 PM
Registered User
is magnum made by the same factory with ASP ?
Nov 09, 2004, 08:19 AM
Carrying a lot of weight!
therotund1's Avatar
I have no official word on weather the ASP and Magnum engines are from the same factory but, from looking at them, I suspect they are. Either that or someone copied them exactly except for the logo's.

The XL70RFS is one of the best engines I've ever had. It takes all the stuff I do to it in stride and never complains. I love it!

Jun 24, 2007, 07:18 AM
Pro Bro # 2398
GassPasser's Avatar
Do You Think There Is Significant Power Increase For Me Switching From The Mag 61 To The Mag 70 ? The Mag 61 Makes My Sig Senior A Tad Sluggish Since Converting Her To A Tail Dragger...thanks
Oct 13, 2007, 01:37 PM
Registered User
How many turns has the low speed needle valve when the engine is new.
Aug 25, 2013, 08:00 PM
Registered User

Same as ASP 91 From Hobby king

This is the same motor as ASP 91 from hobby king. Same company. I bought an ASP 91 4 stroke head for my magnum 91. Same head as the magnum. Hobbypeople 64.95 Hobbyking 29.95 All the parts are the same as the magnum. Same motor and a lot less money. Thought i would share that with you.
Oct 19, 2013, 12:31 AM
co-owner rctoys4all
Originally Posted by therotund1
If anyone has any questions or wants to know about any details that I may have missed, I'll do my best to get them answered.

A special thank you to Don Sims for shooting the video on this engine.

Dave Huff
Hi, I need to replace the bearings in my magnum xl 52. can you tell me the easiest way to do this without disturbing the push rods and rockers.
Oct 20, 2013, 05:02 PM
Registered User
Originally Posted by rcramer
Hi, I need to replace the bearings in my magnum xl 52. can you tell me the easiest way to do this without disturbing the push rods and rockers.
Sorry, but if the Magnum is an O.S. clone, you will have to pull the head to get the liner out to get the piston out to get the crank out to change the bearings.
setting the valves isn't a big deal compared to changing the bearings IMO.
Nov 24, 2016, 01:20 PM
Registered User

Need Magnum xl 70 rfs blue 4-stroke parts replacement


I was wondering if anyony might have the old engine that is no longer needed.

I basically need my cam gear get replaced so I'd buy the whole engine (used one) or the part.

Please let me know if you are interested.


Thread Tools