Zenoah G-26

Model Airplane News, Feb 2004 by Smith, Bruce

Zenoah G-26 Reinventing the standard in gas engines

For modelers old and new, the name Zenoah is synonymous with high-quality, easy-to-operate, reasonably priced gasoline engines. Quite a few of us were introduced to the world of gas engines through the venerable, 1.4ci G-23-myself included. The G-23 was dependable, simple to mount and set up for flight and small enough not to intimidate newbie petrol pilots. With incarnations of the G-23 powering RC fixed-wing aircraft, helicopters, boats, 1/5-scale cars and foot scooters, I like to think that this "little" gas engine has proven itself to be the hardest-working gas engine in the business.

Komatsu Zenoah, a manufacturer of not only model aircraft engines but also ultralight aircraft and industrial engines, chose to retool the G-23 and create a more powerful and efficient smalldisplacement gas engine: the G-26. After a few cursory comparisons, it's clear that the 1,6ci G-26 isn't a mere upgrade of the G-23; its unique features set it apart from its predecessor. Airplane enthusiasts have the RC car sector to thank; the G-26 was primarily born from research and development for the 1/5-scale car market.

FEATURES

* Porting. The most obvious difference between the G-26 and the G-23 lies in the new engine's appearance. The G-26 has an entirely redesigned crankcase and cylinder/head casting that increases the total number of boost ports from one to four. The manufacturer conservatively estimates an 800rpm increase over the G-23 when you use the same 16x8 APC prop, but owners of the better-breathing G-26 report even more impressive numbers than that. Test results suggest a more than 20-percent increase in usable power, and the new castings add only a 2-ounce weight penalty overall.

* Ignition. The Zenoah G-26 benefits from a Capacitor Discharge Ignition (GDI), or magneto, that's common to all Zenoah engines and doesn't require any additional electronics or a battery for spark. I find the simplicity of a magneto engine brilliant, although the required flywheel for the GDI is a little heavier. You can buy a lighter engine of equal displacement, but you will pay a premium. As with all things sophisticated and mechanized, when the weight goes down, the price goes up. The less you get, the more you pay-go figure! But for the money, you won't find a better-engineered, better-manufactured and longer-lasting engine than a Zenoah.

* Carburetor block and linkage. Another obvious reason for the G-26's power increase is its larger carb. The carb is also equipped with a choke, so it's easier to prime and start. A specially designed carburetor block and linkage arm come standard on the G-26, and similar blocks can be retrofitted to the G-23, G-38, G-45 and G-62; that makes it easier to install the throttle control. Those of you who have run gas engines that use Walbro pumper-type gas carburetors know that the linkages can be a challenge at times. Because of the industrial heritage of these engines, the angle at which the carburetor sits, coupled with the style of throttle plate found on the Walbro, doesn't lend itself easily to aircraft applications. The new carburetor-mounting block allows the carburetor to sit in a level position with the throttle butterfly at a right angle to the firewall. The addition of a linkage arm that's reminiscent of a nosewheel steering arm puts the old problem to rest. Although the G-26 is shipped with the new block mounted (the original mounting block is included as well), you will have to do some minor tinkering to remove the industrial throttle-linkage plate and secure the new linkage arm. This isn't a big deal; the instructions included with the engine are clear and supported well with diagrams and photographs. The beauty of the Walbro carburetor is the integral fuel pump that allows you to position the fuel tank farther from the engine where it won't have an adverse effect on the center of gravity and flight performance.

INSTALLING THE G-26

The G-26 arrives complete and ready to run with comprehensive instructions and a sparkplug wrench. The manual has a really cool flow-chart-style troubleshooting guide to assist you with any problems you may encounter-although with a G-26, they are unlikely.

The G-26 comes with a ¼-inch-thick aluminum mounting plate that has the same bolt pattern as the G-23. The magneto on the G-26 is housed at the engine's rear (just like the G-23's), and the mounting plate covers all but a 1-inch hole in the center. You can add your own mounting plate, neoprene vibration isolation bushings and whatever else you prefer; the manual offers specific safety tips.

KILL SWITCH

Absent from the owners' manual are comprehensive instructions regarding the kill switch-a must on a gas engine. Although the manual's wiring schematic shows how and where to find the connection on the coil of the engine, there isn't any additional information that specifies the type of kill switch you must install. My choice is a prewired 10A, 125-VAC toggle switch; it's easy to find at the local auto-parts store. The compatible magneto lead connectors can be found at RadioShack, and they are simply crimped onto the toggle leads.