If this is your first four stroke, use a tach. You can't judge whether the engine is running well without one. Once you have done the adjustments a few times, the tach becomes optional. The highe end is easier to ear tune as when you cross the max, the engine doesn't fall of like a two stroke, but just dies. It is still possible to get them to lean by ringing out every RPM you can on the ground. You want a bit of a cushion.

The black junk may be from a loose muffler. Any movement allowed will cause wear in the threads, giving off a black goo. Use some high temp silicon and give the male threads a very fine coat and then lock the nuts down very tight. If you do this, you will not have a problem with a loose muffler. If you don't, chances are very good that you are going to see wear after just a flight or two and a full failure of the head threads is possible after a while. This applys to all four strokes.

This method works on four strokes and gives you your best running engine. One thing to keep in mind with a new engine, espically the Magnums ( I own five of them from the 52 through the 91) is that they are slow to break in, and you can't get a really realiable engine for several tanks. Some say a couple gallons, but I believe that once you have run five or six full tanks through it, you can go for a proper tune. The 52 should peak out at 10,000 rpm and idle at 2500 when new, and the idle will drop down to around 2200 after things get worn in.


1. Make sure your throtle is opening and closing all the way. You don't want the low speed stop actually preventing the throttle from closing and killing the engine, you will take care of that with radio adjustments.

2. Start your engine and run it at about half throttle for a couple minutes to get things warmed up

3. Go full throttle and adjust the high speed needle for maximum RPM. When you get close, go one click at a time and count to 10 before making the next click adjustment.

4. When you find the top, go back rich and drop 500 to 600 RPM, For a new engine, I would drop it down bye 800 RPM.

5. Slowly drop the throttle as far as you can and keep the engine still running. A small screwdriver at least 8" long to make this adjustment is nice. Again, very slowly lean the idle for maximum RPM. Now drop the throttle again to the slowest it will go and keep running. Adjust the idle again. Note that when making th idle adjustments, only turn the Idle needle 1/16th turn at a time. It is very sensitive.

6. Go back and adjust the high end again.

7. One more adjustment on the low end.

8. Now, the engine is still fully warmed up, at a dead idle jam the throttle full open. If the engine stammers and stutters before gaining speed, the Idle is to rich, lean the idle out 1/16th turn. Keep going until the engine jumps to life with no hesiatation. If the engine dies as soon as you jam the throttle, the idle is to lean, open it up 1/16th turn at a time until you find the sweet spot.

9. Now go back through the setup one more time for the final adjustment. Top end and idle.

THe Mag52 has had some issues with loose Orings on the needle valves. I have one that I could not get to idle below 2800. I haven't gone back and fixed that problem yet as I picked up an O.S. 52 and was using it, until THE CRASH. I totaled out that engine, only the muffler wasn't damaged. I picked up seven pieces of the ground and still missed one pushrod and pushrod tube. Now I have an incentive to get the 52 running right.

My 70 and 91s ran sweet right out of the box. One of the guys always cautions me to slowly increase the throttle, so I don't stall it. BULL. If they won't stand a hard and fast jam to duty from full idle, they are not adjusted right. I'm still prefecting, shall we say, my landings and if I can't jam the throttle and get out of trouble, then I may loose a plane. It has happened to me, and I ended up fishing the plane out of the pond by our runway, after it clipped a wing on a fence post and tore the wing of. My problem then was trying some Cool Power fuel. Don't like it and won't use it again. The Omega 15% works very well. The Cool Power 15% gave me trouble in two different engines.

Don