JAG Engines

String Trimmer Conversion


Thank you for your inquiry into the JAG Engines weed-eater conversion. You will have many happy hours flying the MTD engines with the JAG Engines conversion products, mufflers and tuned pipes. Our parts will allow you to convert your MTD weed-eater engine for as low as $56 complete! Harbor Freight Tools, (800) 423-2567, sells the complete long shaft weed-eater for about $55. Give them a call. The engines are sold as “re-conditioned” but only have from 5 to 25 minutes time on them. They are simply run, re-adjusted and put back in the boxes and, by law, have to say “re-conditioned” on the box. We use them in our 720R models and sell them completely converted for $178. MTD makes over one million of them per year in Arizona.


The MTD engines are very durable and well made. They have chrome cylinder bores, twin rod needle bearings and twin crankshaft ball bearings. The rod is made from two forged pieces of steel and is bullet proof. The engines are guaranteed for one year and parts can be obtained from most lawn mower repair shops or JAG Engines.


Conversion of both the long shaft versions (engines with built-in clutches in the weed-eater) and the short shaft engines are simple and fun. We supply all the parts that you will need to get your engine mounted on your favorite R/C plane and go flying. Our instructions tell you step-by-step how to make your weed-eater into a great airplane power plant. The 720R and the 725R are both long shaft engines. We now also sell True Turn Spinners!


We now sell new converted engines using the C.H. Electronics after market ignition systems. These systems are just fantastic! You can get about 8% more RPM than the magneto versions due to the fact that they can be adjusted to maximum timing position. You can’t do that with the Magneto systems. The weight is reduced from 58oz. To 49 oz. Plus muffler and the 4oz. ignition system. You can adjust these to run in either direction! Many of the JAGUAR 31cc engines have been sold to guys making twin engine airplanes. They are SUPER!


Our engines are flying all sorts of planes from scale Cubs on floats to Citabrias, Stinger 120s, PT-19s, Goldberg Sukhois, Pip Dream trainers, Huskys, Midwest 202s, 300s and most planes from 68” to 110” wingspan depending on the wing loadings. The lighter the wing loading, the better. We are still flying the 82” sport plane weighing 14 pounds that we use in the California R/C Marathon event each May. It flew for 185 miles nonstop on only gallon of gas for a 3rd place trophy! Team Infinity flew 235 miles with their specially designed airplane. We used a 16X12 APC prop on the flight and the engine did not miss a beat. Most planes designed for a 108 two stroke or 120 to 150 and up four stroke engines will work fine for the MTDs. The new 80’ Bridi Kaos and Killer Bee kits are inexpensive and perfect for these engines as well as some of the Bud Nosen Kits. Get you Ryobi up and flying ……….. You will really enjoy these great gas engines!


MTD 31cc Long and Short Shaft Conversions Instructions



Click here to email JAG Engines

Snail mail:

  JAG Engines
  16073 Muscatel
  Hesperia, CA 92345
  (760) 244-7270


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Dan Egelhoff