78'' Extra

[hone]

Nice job Joe!

As has been said previously, you could definitely lean out your low end mixture about 1/8 turn, maybe a hair more. It also sounds like it might be sagging a bit on the top end...so you could also richen the high speed mixture about 1/8 turn.

Normally, to tune a motor like this, I start at the recommended or factory settings, then go 1/4 turn richer (very rich). Then I let it idle and advance the throttle quickly. It should respond immediately. Then lean the low speed mixture 1/8 turn and try it again, noting how it responds. It should respond quickly but it will be running rough and burbling occasionally. Keep leaning the low speed mixture until it no longer responds well...it will bog when you advance the throttle. Then go back the other way, about 1/8 turn richer than where it bogs. The idea is that it's just rich enough to respond well.

Then set the high end...Go full throttle and take a RPM reading. Lean the high speed mixture 1/8 turn and take another reading. Keep doing this until you have reached peak RPM. Then richen the mixture barely enough to have the top RPM come down 100 rpm or so.

Thanks for the tips!

I'll have to write this all down for next time i go out to the field ahaha.

 

[Bigroger]

That is some fantastic information Cody.

I keep seeing guys at my club arguing all the time about tuning two strokes. Seems every one has their crazy theories and yet they all seem to run horrible at my club, gurgles and lack of power etc, hard to start and so forth.

When I see videos of you guys that are on the ball, your motors always seem crisp and responsive and awesome.

So now I know the secret!!!

 

[Rick dazzler]

Tuning is simple..
Peak the top end for max rpm. As said back off 1/8 turn
Set your low end for best idle and mid range transition.. This means no mid range burble
When you turn the low and hi end needles move them 1/8 turn in small increments. it don't take much.. Although I don't believe in factory setting (altitude plays a huge roll in this) 1.5 turns out is a good starting point then tune from their..
It's not that hard after you do it.. Plus you get to fly more than 5 minutes! I got a 10s electric.. Hate the 4-5 minute flights.. Love the response

 

[3dNater]

Good chatting with you today Chad

 

[Rick dazzler]

Good chatting with you today Chad

You too nate! Thanks!

 

[hone]

Got a few more flights on the Extra. Tried a 20b but i think i might need to go down to a 20a. The engine would bog/die if kept at full throttle too long so we richen it a touch and i also cut a hole in the covering so air could come out of the tunnel. That helped but it didn't solve it. The cowl is getting plenty of air in/out. The engine had good transition with no hesitation and idled well so i believe it is tuned good so i think the prop is too much(i'm at sea level). IIRC the tach showed only around 6450-6600 at full throttle, i think others reported 7000 but i don't know his elevation.


Some people don't like that the plane comes with aluminum LG but I actually like that because if i have a dead stick that results in a less than perfect landing i can just bend the gear back into shape. I'll probably get the carbon gear when everything is broken in and running perfect but for someone getting there first gasser i think the aluminum will save you money in the long run.

My CG is a little further back than i like. I'm actually perfectly neutral when i roll inverted but i prefer having it a little forward of that. I'm using 2 x 2s 1300s to power the system and i have no more room to move them forward so i'm going to get some 1600-1800s. Hopefully that'll put me where i want to be and i'll be able to fly an extra flight or two before switching packs.

I wanted to put a ES pipe on it but that would move my CG further back right? I guess replacing the carbon spinner with something heavier would be a good place to start. The one i have is 3'' and looks a little small on the plane actually. Any suggestions for spinners would be great.

Since the engine is still breaking in i've been flying mostly precision and it is LOCKED IN! I love it! Even with the CG not perfect the plane is tracking great. I can't wait to start bringing it down low.

 

[3dNater]

Great report! I'm looking forward to more info as your motor continues to break-in. It should make more power as it breaks in as well so don't give up hope on the 20b yet! I would fly it will a little less load until it is broken in and making more power, then see how it handles the 20b.

 

[hone]

Thanks.
I'm going to put the 19x8 back on it until i'm done breaking it in. When i switch to full synthetic i'll go back up in prop size but i'll probably put the 20a on there.

I really like how fast this plane is in the air. It's feels a lot quicker in the air than my 6s powered 71'' Slick. I think it has a lot to do with the airfoils on the planes too though. The AJ has a REALLY thick airfoil compared to this Extra.

 

[hone]

Forgot to post the pic from today before the first flight

 

[3dNater]

It's looking SEXY

I think my 70" gasser slick is probably a lot faster than a 6s powered one. My gasser goes pretty fast when you open it up. I am taking the PTE 36R off of it tomorrow in anticipation of the EME 35. The PTE is sold so it has to ship out this weekend. It was a decent motor and pulled really hard but I have high hopes for the EME providing smoother operation and reliability. I still hope to get this EF 78 down the road