Once you get the low speed needle to keep a set, transition becomes good. On an 11x7.5 we race SPAD Das Plas Sticks, and the engine will out run, and out perform the OS 55 on the same airframe. 3 Stars because the bearings suck!! Once you start eating glow plugs, replace with Boca Bearings. Had one engine warrantied because of the bearings came a part and shot the prop off at 14K RPM. It also is a very sloppy engine, blowing raw fuels from about every orifice you can imagine..but on sale, you can get two of these to one OS, and make way more power on bigger props. (Posted on 8/4/12)

After repeated unsuccessful attempts to get the engine to idle and transition to maximum RPM I replace the carburetor and rear needle valve assembly, Part No. 283023. The engine now performs as outlined in the owners manual.

The warranty period expired prior to my use of the engine and no offer to replace the defective parts was made, For this reason my evaluation of the product and its support remains low. (Posted on 7/12/12)

After doing the break in per the instructions (actually 3 12oz tanks for me) I just went
flying keeping it rich, didn't touch the low speed neddle and wow! reliable and never quits, very decent performance, I have it in a great planes sport mustang with a 11x7 apc and I almost keep up with my buddy who has the same plane but with an OS 55AX! keep in mind mine is stil very rich. I'm using the optional pitts muffler and it is great BUT you need to plug one of the exaust pipes or else you wont have enough back pressure in the tank and that leads to an unresponsive needle valve and lean runs. YOU CAN'T GO WRONG WITH THIS ONE! I have several OS and this one is on par except for the price. Oh and even if it's rich with a 12oz tank I fly 15 minutes and still have plenty of reserve to go around another 2-3 minutes. A+ !! (Posted on 11/1/11)

Pretty easy to start up by hand, even during the break in process. Runs great and not as messy as other engines around. I installed mine with their Pitts Style muffler and is sounds nice with little to no mess to clean up. (Posted on 10/14/11)

We have contacted Ron with suggestions and if the engine is still not performing to standard, we have asked that he send it in for our service tech to test. Matt

If the rating scale had a less than one star I would use it. I ran the engine on the test stand, in accordance with the instructions pack with engine, using 5 10oz tanks of fuel. Installed the engine in the airframe and spent several hours at the field attempting to finalize the fuel settings. First day unsucessfull. Seconday day after many tries to get the settings set so the engine would remain running and transition from idle to high speed, I attempted a flight. It lasted about 3 minutes and ended in a dead stick landing.The engine will be relaced with one that works. (Posted on 10/9/11)

This motor once tuned properly is awesome. Great power, great for 3D, no worries of a dead stick landing. At full throttle with a 12x4 prop was cranking 13,900 RPM. Love the blue head too. One tip though, take the low speed jet out and use some blue threadlocker on it, reinstall about halfway and let dry. Once it dries and you break it loose with a screwdriver, it will turn a little harder and not wonder in flight. Before I did that, mine was turning by itself in flight and giviing me a headache. (Posted on 4/25/11)

Great engine! needs a little extra breakin but after that very easy starting...with plenty of power! great for 3D type flying! a little tip; sealup the muffler joints with hi-temp silicone. would buy another! (Posted on 10/21/10)

I have these engines on a tucano and a spitfire, and they are powerful with a great sound at high end. I do agree they are a bit messy, but maintenance/cleaning is part of my hobby routine. I have been flying both engines regularly for 2 yrs with no real other issue other than the remote needle valve bracket. I know we are not to crash them nose first, but stuff happens.post crash damage to the same engine required replacing the needle valve bracket twice. great value for the price. keep making them. both my engines run on OSA3 plugs. (Posted on 9/30/10)

At first, I was disappointed with this engine, all my flights always ended with dead sticks, then I re-read the manual and realized that it recommends "hot heat-range glow plug", since then I´m using OS A3 glow plug and WOW!, it is my favourite engine, reliable, consistent and VERY powerfull. And the fuel consumption is the same of my .46 engines, fantastic !!! I love this engine, soon will order another one. (Posted on 8/31/10)

The magnum xls 52a engine is a great engine to use. I only encountered one problem, I replaced my #3 plug with a #8 plug. After I replaced the glow plugs the motor fired up and ran like a champ. (Posted on 8/31/10)