RCU Review: RCGF 120cc Twin Cylinder Gasoline Engine

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    Contributed by: Geoff Barber | Published: September 2015 | Views: 14080 | email icon Email this Article | PDFpdf icon
    RCUniverse.com Review of the RCGF 120cc Twin Cylinder Gas Engine
    Geoff Barber

    Email Me

    4029 E. Golden Acres Drive,
    Sierra Vista, AZ. 85650
    Email: rcgfsale@zjrcgf.com


    It seems as though there's a lot of competition in the gas engine market these days, and there are a few names that everyone is familiar with. Some of the big ones are DA, DLE, and 3W - just to name a few. There's more to the gas engine game than just them! Over the past decade, several smaller companies have sprung up - some have stayed, and some have gone away. But, just because these smaller companies may not be as well known, doesn't mean they don't have good products at good prices!

    RCGF, a Chinese manufacturer of gasoline engines, designs and manufactures engines specifically for the RC aircraft market. They have a line of gas engines as small as 10cc, all the way up to 120cc! In addition to the vast size range, RCGF has a number of twin-cylinder engines as well - 20, 30, 40, 60, and 120cc - all are a 'boxer' type, meaning the pistons travel in opposite directions to minimize load and balance concerns. This, in turn, also reduces vibration.

    While RC gas engines have been around for quite a while, the demand for high quality twin cylinder variants is fairly recent. But these twins have come a long way in a short time! The RCGF 1200cc twin is relatively new on the market, but definitely fits the 'high quality' definition.

    So, let's open the box and see what's inside!

    • Specifically Designed for RC Use
    • One Year Limited Warranty
    • 'Boxer' Design Reduces Vibration
    • Single piston Ring Design
    • Narrow over-all Width
    • Walbro Pumped Carburetor
    • Lightweight Ignition Module
    • Standoffs and Radial Engine Mount Included

    • None as Tested

    Skill Level:

    Time Required to Build:

    Frustration Level:

    What do these ratings mean?

    Name:RCGF 120cc Twin Cylinder Gasoline Engine

    Price: $689.99 (Accurate at time of review)

    Engine Type: 2 Stroke Gasoline Engine
    Cylinder Displacement: 120cc (7.2 ci)
    Weight with Ignition and Mufflers: 2830g (99 oz)
    Weight w/o Ignition and Mufflers: 2450g (86 oz)
    Bore x Stroke: 47mm x 35mm (1.85 in x 1.37 in)
    Carburetor: Walbro

    Ignition: DC-CDI (Computer Controlled, Auto Advance, Electronic Ignition System)
    Power Supply: 4.8 - 8.4 Volts
    Speed Range: 1500-9000 RPM
    Recommended Fuel Ratio: 25-40:1 (ashless 2-stroke oil)
    Recommended Propellers: 28x10 29x9 Two Blade

    My engine was delivered directly from the factory in China. It was packed in dense foam, and although the thick cardboard box showed evidence of mishandling, the contents were in perfect order.

    I removed all of the parts from the foam, did a quick inventory, and every piece was accounted for! The engine itself looked very nice and the aluminum was nice and shiny.

    The RCGF120 has a six-bolt propeller hub, and should keep any prop in place. Even the cast finish on the cylinders was nice, and I found no pitting. RCGF has a new electronic ignition module! This new version is capable of handling an input voltage up to 8.4V without the need for a regulator - this means that a 2S LiPo or LiFe battery can be used with the ignition.

    The canister mufflers are welded aluminum, and look nice - they should do a fine job, and the outlet tubes are long enough for even the largest of cowls. The included hardware is, of course, Metric and very high quality.

    A large-bore Walbro carburetor is standard equipment on the RCGF 120, and it's mounted for easy throttle pushrod alignment.

    As I have done in the past, I disassembled the carb to look for debris - as usual, I found the carb to be clean!

    With carburetor removed, its aluminum mount can be easily seen. Four more machine screws hold the mount and reed block in place - I removed them to inspect the reeds and check the visible part of the crank case and shaft - all looked to be in good order, so I reassembled the engine.

    What's this? Could it be? A drill jig included with an engine? Well this is most definitely a first for me! Thanks RCGF! This was a most unexpected bonus!


    Though the manual is not engine specific, it does a great job of covering all the basics - from which oil to use and how to perform the 'break-in' procedure to helpful tips on troubleshooting and safety. The manual I received was in full color as well!

    Engine Installation

    Let's get this big-bore engine installed! I will be installing this 120cc powerhouse in my new World Models 30% PT-17 Stearman. Check the RCUniverse.com homepage for a separate review of this legendary WWII primary trainer aircraft!

    Installation began with making a template - I used a piece of card stock (tag board) to make the template. The outline was traced from the engine's mount, and the mounting holes were added with help from the dimensions listed on the RCGF website. I also added the 'cross hairs' - this is essential to aligning the engine on the firewall. Without these lines, I wouldn't be able to correctly place the engine on the firewall. With the template now taped to the firewall, I was able to drill the four mounting holes. The template was then removed (I keep then for future use) and four blind nuts were driven into the holes.

    Because the Stearman has a very thick firewall, I had to purchase longer mounting bolts. This was certainly not an issue, as I was able to purchase them from my local home improvement store. The engine was then secured to the airplane, and I used a few drops of ZAP Z-42 Blue thread locker to keep the bolts from vibrating loose.

    Though technically NOT part of the engine install, I felt it was necessary to show the tank assembly and installation. As you can see, I set up the 1500cc (50 ounce) tank with a three-line system. This will make fueling and defueling the tank easier. The tank was installed and padded by DuBro 1/ 4" foam rubber to help isolate it from vibration. While this is not absolutely needed with gasoline, it certainly doesn't hurt!

    The vent line from the tank was routed to the belly of the plane and secured - this will keep any fuel overflow from damaging the aircraft. The tank's pickup line was routed to the carburetor and secured with a short piece of safety wire. I would rather the fuel line stay attached to the carb. The throttle servo and pushrod were installed next. Because the carburetor sits very low on the RCGF 120, I relocated the Hitec HS-5485HB Digital throttle servo so the pushrod (made from a DuBro 4-40 pushrod and two DuBro Heavy-duty ball links) had a straight line to the throttle arm on the carburetor.

    The canister mufflers were installed after verifying the throttle servo was properly set.

    The last thing to install was the electronic ignition module. Since there was plenty of room above the engine on the firewall, I secured it there with a few zip-ties and more DuBro 1/ 4" foam rubber.

    With the spark plugs and plug boots installed, the engine was just slightly too wide for my Stearman's cowl. I had to cut clearance holes for the plug boots and exhaust tubes, but I don't think it will distract from the look of the completed plane.

    With the cowl in place and trimmed properly, I installed a custom-made 1-1/ 2" aluminum propeller spacer and a Falcon 27x10 Civilian propeller. These new props, available from Justmodelprops.com, are beautiful! A Civilian prop from Falcon will add that 'special touch' to any scale project!

    Falcon Propellers and Bob's Hobby Center at Steve's Hangar
    Bob's Hobby Center


    Falcon Propeller US Distributor

    Check out our unique range of Civilian Propellers. Based on designs from the 1950s these beautiful scale props will provide great performance and a finishing touch to your aircraft. ?No Cub or Stearman should be seen without one?

    At Just Model Props, they carry the USA?s largest range of ?top quality? model propellers ? whether you are new to the hobby or a seasoned veteran they have the products to deliver the performance you require. Their range is constantly expanding to meet the demands of their customers!

    Now I know what you're thinking. Where's the flight report and video? It's coming, I promise. They will both be in part two of this review! So stay tuned and check out the RCUniverse.com homepage for part two - it'll be coming soon!

    4029 E. Golden Acres Drive,
    Sierra Vista, AZ. 85650
    Email: rcgfsale@zjrcgf.com

    P.O. Box 815
    480 Bonner Rd
    Wauconda, IL 60084
    Phone: 800-848-9411


    Distributed through
    Bob's Hobby Center
    540 N Goldenrod Rd
    Orlando, FL 32807
    Phone: (407) 277-1248

    Distributed through
    AirBorne Models
    4749 - K Bennett Drive
    Livermore, CA 94551
    Phone: (925) 371-0922

    Distributed by:
    Frank Tiano Enterprises
    3607 Ventura Drive E.
    Lakeland, Florida 33811
    Phone: (863) 607-6611


    11215 Paine Street
    Poway, CA 92064
    Phone: 1-858-748-6948

    Comments on RCU Review: RCGF 120cc Twin Cylinder Gasoline Engine

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    The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review.

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