Rotax Two Stroke Engines and Ultralights

[Paul Weiss]

I recently bought a CGS Hawk Classic ultralight and it has a two stroke Rotax 503 engine on it.

 

I am a GA pilot so ultralights are new to me. A number of guys at the airport I fly out of keep telling me that Rotax two stroke engines are unreliable and will "STOP" suddenly and without warning while flying! This doesn't give me very much confidence to fly the Hawk as I am afraid the engine will quit without warning and if I am not within gliding range of the airport I will have to find someplace to land quick. I would like to hear from other ultralight pilots who fly Rotax two stroke engines and how you feel about the reliability of the engine.

 

 

[David F]

Hi Paul

 

They have to be treated right to get reliable performance.Use the same oil in the premix all the time and run them often (a long period of non operation can be damaging even if the hours are low ) If properly looked after the 503 has a good record.

 

Regards Dave

 

 

[Teckair]

Hi Paul,

 

The Rotax 503 can stop suddenly if not treated correctly, you need to learn about that engine before attempting to fly the aircraft. Also you need to get some training on a low speed aircraft before attempting to go flying as it will be greatly different to a GA machine. 30 years ago ultra light aircraft got a bad name due to GA pilots killing them selves in these planes thinking they would be easier and more simple to fly.

 

Regards Richard.

 

 

[Guest Crezzi]

IA number of guys at the airport I fly out of keep telling me that Rotax two stroke engines are unreliable and will "STOP" suddenly and without warning while flying!

I hear this a lot also - It's much easier to keep a bad reputation than to gain a good one. I've done 100's of hours with Rotax 2-strokes & the very few failures were things like carb-ice & fuel (which would also have stopped a 4-stroke). The Rotax 503 is probably the most reliable 2-stroke you'll find on an aircraft - arguably comparable to certain 4-stroke engines.

 

Good advice from the other posters also

 

Cheers

 

John

 

 

[kevinfrost]

Hi Paul

 

An EGT gauge will be cheap insurance. Keep the engine within the recomended temp range and use the recomended oil and you'll get a long service out of the 503. I've read where some have got close to a 1000hrs out of the the 503 without touching it. We've had a/c that have used both the 582 and the 503 andHad a very good run with them, except for a sticky ring in the 503 which caused that cylinder to run lean and nip. I consider that problem was our fault and not the design

 

 

[Guest pookemon]

It seems to me that no matter what engine you mention, someone will be right there at that moment that will pipe up and say "Don't buy one of those...". I first heard it when I was considering building a Sonex and mentioned the VW powerplant. Next I heard it regarding the Subaru EA81's and when I picked up my Karatoo I heard it about the Jabiru engines. About the only engines I haven't had someone say "Don't buy one of those..." are the Rotax motors. IMO all motors are just as safe as any other. As long as you look after them the way they are supposed to be looked after. If Rotax 2 strokes weren't any good - they would be out of business - the same goes for Jabiru, UL Power, Ecofly etc.

 

 

[Guest ozzie]

CGS Hawk, one of the long time players. These can carry a fair bit of weight as it was designed by a big boy. The company recently changed hands when Jim Z's health started to fail. So no problem for parts. With a active Yahoo groups for the Hawk as well there is a feast of knowldge is at hand. As for two strokes it all comes down to how they are operated. With a second hand one past history is going to play a big part in the future reliability of your engine. One of the most popular 503 users are the Saphire ultralight so they would be the best local source for info on them. Has this Hawk been in storage? if so rebuild the entire fuel system. New points or at least some new grease on the rub block. Once you relearn how to fly a lightie you will really enjoy it.

 

Ozzie

 

 

[skeptic36]

Here is a thread on the subject which should give you an indication of reliability

 

Regards Bill

 

 

[Paul Weiss]

Thanks guys for all the info. This airplane has been maintained by a Rotak mechanic and before he sold me the plane he rebuilt the engine and had gone through the entire plane. So, I feel confident that all is well. He also talks to me everytime he see's me about what I am running on Exhaust Temp and Cyl Temp as he is concerned about how the engine is running. So, I have a lot of good advice around - I just need to plant my butt in the airplane and get some time with it to feel more comfortable flying it.

 

Thanks for all the words of wisdom.