Evolution pts tuning trouble
 

Hello all, First post here. Iv'e been lurking for awhile but have a question. I have a hangar 9 mustang pts and have flown it for two years. I decided that I was sick of the the evolution pts engine's sluggish transitioning, so I removed the blue collar on the low needle and began tuning. No matter what I do I can not seem to get it right. When I finally got the engine to transition flawlessly the engine would load up an die at idle after 10 or 15 seconds(dead sticks on landings). Yesterday I flew 2 flights and low needle is about 1/4 out and high needle is less than 1 turn out(probably 7/8 or so), which is where the high side has always been. This seems awfully lean to me but the engine will not run any fatter. I am beginning to wonder if there is some sort of mechanical failure somewhere else??? I run byrons 10/18 fuel, and use hangar 9, 4 stroke plugs, both were new yesterday. Currently running a 10x6x3 Master air screw prop, but changing to a 11x6x2 if I can get this thing to run right. Any suggestions are welcome

Sorry to beat a dead horse but searching hasn't answered my questions, hopefully someone can help me....Thanks

RE: Evolution pts tuning trouble
 

Have you checked the muffler nipple and cleared it?

On the Evolution engines this frequently gets clogged with engine "goo" and causes all sorts of tuning problems.

I just jumped off another thread where someone else was having similiar problems and once he cleaned out the nipple, all of his issues went away.

You seem to be overly richening the engine to get the transition right.

This is symptomatic of lack of pressure, so it points to the nipple as well.

The Evolutions ( other than the dreaded 1.00NX ) don't usually have the transition problems that may plague say the SuperTigres.

RE: Evolution pts tuning trouble
 

opjose, thanks for the reply.

I actually was just reading about the exaust nipple on another forum, also the exaust joint as well....Mine leaks of course and I get the grey residue on the side of my plane. So this is the next thing I will try next week, Its snowing here today.....blahh. I actually never thought of back pressure being an issue, but it makes good sense.

About the settings of the needles, I can't be positive because it has been awhile since I removed the low limiting collar but I was thinking that the factory setting was over 1 full turn out. So I was worried I may being trying to run the engine lean, can anyuone give me a ballpark figure on the low needle for a starting point. Setting my OS engines is a breeze, but this thing just doesn't respond like an OS. I would have made better notes about the factory settings but I didn't think it would be such a pain to tune.

Can you tell Im a noobie.....lol

RE: Evolution pts tuning trouble
 

Another thing I've done to my evolution engines 46 and 61's is remove the baffle from the muffler. Ditto on the nipple, happened on a flying buddys plane last weekend when we were out.

flynte