Alpha Trainer engine question
 

Greetings. I have a new Alpha Trainer 46 DSM2 with the Evolution Trainer Power System that I have had for about 2 months and have recently had a few problems with the engine. When I first got the plane I flew it around for at my field a few sessions stock and it was OKAY. I did have to retune it every single time I flew it so I did some blogging and everyone said to get rid of the flywheel and 3 blade prop. So I took off the flywheel and put on a 10X7 prop and it ran really good after a tune with the new changes and did okay that day. I have flown it twice since and have had nothing but problems with it. First off i could not get it to go from idle to full throttle at all, it instead goes from idle to running rought then after about 3-6 seconds it runs full. Today it did the same thing but now after it reaches flight speed or full throttle the engine pulses and has air bubbles in the top of the fuel delivery hose, ie the pulse. It also has also developed a into a leaky engine, but yeat i have check all the screws. Im thinking its the engine, but not sure. I also thought it sould be the fact that the Alpha Trainer had no foam around the tank. I did a pressure test on the tank and it is solid so I do not think its a leak nor do a see one. I have thinking I should just replace the engine and tank with a Super Tigre 45 ABN. As for a new tank I am not sure what to get in an equal size to the stock one in size and this time run some foam around it. If you have suggestions let me know I really like this plane and dont want to lose because of something dumb.

I was also wandering as for removing the low idle adjustment limiter i am not sure how to do this. can you guide me?
i got the high idle adjustment taken care of i just knocked the small pin down.

RE: Alpha Trainer engine question
 

Remove the blue collar from the low end adjustment.

Open the carb barrel 1 millimeter

Close the low end needle and re-open it 1 1/5 (One and one fifth) turns

Replace the blue collar.

RE: Alpha Trainer engine question
 

That poor transition going from low speed to high speed is simply a tuning issue. The low speed needle is likely too rich and needs to be leaned a bit. To test your low speed needle setting, start the engine and leave it running at idle while you pinch the fuel line going to the carburetor shut with your fingers:

A) If the engine runs and runs and runs then speeds up and quits, your low speed needle is too rich. Lean it 1/8 of a turn and retest.

B) If the engine quits almost instantly without picking up rpms first, your low speed needle is too lean. Richen it 1/8 of a turn and retest

C) If the engine picks up rpms a bit then quits after 2 to 4 seconds, your low speed needle is just about right.

As for the engine "pulsing" at wide open throttle and air bubbles appearing in the carburetor line:

1) Check your clunk and clunk line inside the tank, make sure the clunk line is free from splits and tears. Make sure the clunk hangs down toward the back of the tank so that there is still 1/8" or more of space and the clunk can't rest against the back of the tank. Feel free to replace your factory clunk with an O.S. Max bubbleless clunk.

2) Check the line from the tank to the carburetor and make sure that it is free from spits and tears. Replace any fuel line that seems less than soft and flexible. Use Du Bro fuel clamps on any fuel line connection that doesn't feel snug or that seems like it could easily pop off.

3) Check the remote needle valve/needle valve assembly and make sure that everything is tight and secure.

4) Check all of the fuel lines for proper length. The carburetor, remote needle valve, and exhaust lines should be long enough that they aren't tight or strained to reach their connections. They should also not be so slack that the fuel lines bough out or form u-bends before reaching their connections. Trim or replace any fuel lines that don't look "just right" with regard to length.

5) Go through all of the cylinder head and backplate bolts and check them for tightness. Make sure that all of these bolts are very, very snug. Check the carburetor and make sure it is mounted tightly to the crank case. Air leaks at any of these points will cause the engine to run lean and will make your engine almost impossible to tune.

6) Run your engine at full throttle and stand behind the prop looking carefully for leaking fuel. A little bit of extra fuel coming out of the exhaust port or muffler seams isn't any big deal. Fuel dripping from the seam between the cylinder head and the crank case or fuel spitting out the front of the crank shaft can be another story. Either of these conditions can indicate engine component failure and will result in the need for a new cylinder head gasket, new bearings, or the like.

7) Do your best to remove your fuel tank, pad the fuel tank with some protective foam where it will fit, and then put the tank back. It never hurts to try to isolate the fuel tank a bit from the vibration of the fuselage.

The Evolution TPS is a terrific engine. You've done the right thing by removing the flywheel. Try to get both the high speed needle and low speed needle limiters off so you can actually tune the engine. If you go through all of the above steps, you'll be rewarded with a nice reliable, powerful .455 twin needle dual ball bearing sport engine.

As for props, there isn't anything wrong with 3-blade props in general. The Evolution TPS prop, however, is a blunt-tipped 10.5 x 4 that is very inefficient by design and is usually balanced poorly. I'd recommend that you try an 11x5 two-blade prop for training, then an 11x6 two-blade or 10x7 three-blade when you're looking for some extra performance. The 10x7 two-blade prop you're using now is more of a speed prop with your engine and it will make the plane land a little fast for training.

Good luck with the troubleshooting and tuning!

RE: Alpha Trainer engine question
 

You can also take the blue collar off of the low speed and leave it off if you want. that's what I did with the one I have on my LT-40 beater plane. Sometimes the mass of the pin and collar seems to allow it to rotate with engine vibration, changing the mixture. It's not normal, but I've seen it happen. Once you take the collar off, you'll be left with a screw sticking out that you can adjust with a screw driver easily enough, and that will stay put on it's own more easily.

I left the flywheel on the one I have (which I bought used), and I don't notice that it's there. I run an APC 11x5, and I took the baffle out of the muffler for a little more power (and quite a bit more noise).

I've had 20+ students now with the .45 and .61 flavors of the Evolution engines in various trainers, and I've yet to see one that didn't run great. They even flip start really easily once you learn how they like to be primed (a bit richer than some other engines).

I do like the super tiger engines, but frankly, I think the evolution is better made, easier to tune, and more consistant out of the factory than the ST. YMMV of course, but given a choice, I'd go with the Evolution in any plane of mine.