ROTAX 447 CARBY TROUBLE

[flyerme]

STILL no GO? just purchaced another 447 near new and put it in,So new engine and carbie also new prop new fuel and still same prob diconnected all electrics no change only leaves 1 thing thats origanal(the only thing I havn' changed) the exhaust system..well turns out some hillbille somwhere along the way decided it would look nice undernieth and so cut the power chamber and added a piece of car exhaust did away with the elbow ..so its now a 2 piece system thats longer than origanal...Not a smart thing to do as the rotax requires an exact distance as it is a TUNED pipe,,so now looking fro an exhaust!!! anyone have an exhaust floating about for the rotax 377,477,503 need elbow and power pipe(exspansion chamber).

 

 

[farri]

A little story about the exhaust System.....Way back in the early eighties when I built my Chinook, the engine that I chose was a Fuji Robin 440.

 

Because money was scarce and I saw it as a challenge, I made up the muffler myself, here in my farm shed. It was a success! The engine developed full power and the aircraft flew well.

 

Mufflers only last for so long so when I needed a new one I decided that this time I would get one made up by a professional... I gave the guy the old one as an example and he was pretty confident that he could do better.

 

Finaly my muffler was ready.... It had taken twice as long to make and therefore the cost was almost twice as much as what he had quoted me and it didn`t look much better than the one that I had made....Never mind, I thought as long as it works.

 

I put the new muffler on, ran up and down the strip but couldn`t get enough power to get airborn.... Now I was concerned but I suspected the muffler was the cause..... What do I do now I thought!..I wasn`t going back to the guy who had made it because if he didn`t get it right in twice the time he`d quoted, I reckoned he wouldn`t get it right the next time either, so I cut it up, increased the expansion chamber ( bit of an experiment ) got full power back and I was flying again.

 

Moral of the story:

 

On two stroke engines the muffler is extremely important to the performance of the engine.

 

Frank.