hey guys ...i just got a new Evolution .90...runs fine for a bit then at half throttle it starts dieyng...wants to quit...put to full throttle and it seems as if it gets hot and starts to lock up...blue paint on head turnming brown so im thinking it is getting way to hot....running omega 15% fuel with castor synthetic mix...acti it did lock up on i think Byron fuel th omega is 4 stroke fuel.,,, any suggestions or thoughts???

At half throttle it wants to die, maybe you are running too rich on the high end?

yes its actually my dads engine...he put a new great planes Escapade together and put this evotution on it...90 flies great at half throttle but after a few min. it starts slowing down and wont pick back up ... so it stalled and he fortunatly dead sticked it to safe landing on maiden flight... so we fired back up on ground let it set and run and same thing happened ...so i was playing with mix at half throttle and it locked up and spun prop and nose cone off.. after few moments u can spin engine by hand again...we been flying for a long time and never nothing like this ...is the fuel were using it evolution wrong?

First make SURE you are using the RIGHT PROP!

The wrong size prop will cause the engine to overheat.


If your engine came with the limiters, REMOVE THEM and tighten the spring clips so the needles will not turn.

The Evolution engine needles tend to turn by themselves with engine vibration unless the spring clip is pretty tight. That throws off tuning attempts...


Richen the high end a FULL turn out.

Get it running consistently, even if it is not developing full power.

Then you can use a laser temp probe to check the head temp right around the glow plug.

The head temp should stay in the 280-320 degree range. If it is lower than that, lean it out and listen to the engine.

Keep leaning until the temp is in this range then do a pinch test.


Lean the engine until it seems not go be running any faster at full throttle, then back it out about 1/4 turn or more.

At full throttle the engine should speed up almost immediately when you pinch the tubing.

If it doesn't the engine is too lean.

If you pinch and hold the tubing at full throttle and the engine does not cut off within a second or three the engine is too rich.


Once you have the high end set, bring the engine back down to idle.

Connect the glow igniter. If the engine speeds up with the igniter in place the engine is too rich on the low end and will bog down and die at normal idle.

Adjust the low speed so that the needle is just at the point that removing the igniter has no effect. Then double check by running the engine up to full throttle.

After this... if the engine reacts quickly to full throttle, it's fine... if it stumbles then speeds up richen the low end. If it stumbles and dies, check the high end.

Jose: Thanks for the information. I had several Evo engines that gave me the exact same problems. Everyone I worked with at the field did what they could to get the engines to run long enough to fly with. I had an EVO100 on my Excelleron 90 pattern plane but could never get a complete tank through the darned thing - it would fly for maybe two or three orbies before the engine died. It would never handle a transition from idle and ran lousy at full throttle. I replaced it with an OS 1.20 AX.

I eventually gave them all away. I hated them.

If I had your process back then, I might have been able to solve the problem and get the engines to run right. I know many use the EVO engines that post here and I'm sure many got irritated by my posts saying how lousy I thought the engines were.

Anyway, your solution sounds like a good one, so thanks!

CGr.

Hi!
He runs it too lean!

thanx guys....when i got home from work yesterday dad had called and said he put some older fuel he had wich was 10% and it ran fine and head temp was like 240- 255....thanx for the info gentlmen..