w8ye

My Feedback: (16)

To opjose and ahicks . . .

A copy of the post by ahicks was placed in the sticky at the top of the page along about post # 28 or somewhere close.

Mr67Stang

Very well said. To add to that, when our planes get in the air the engine is allowd to "unload" from it's static environment on the ground and will spin upwards of 200 rmp more than what you are seeing on the ground. This will cause a leaner condition in the air. A fat (rich) setting on the ground is the only way to compensate.

If you can not understand why it spins faster in the air than on the ground, picture if you will you are paddling a cannoe that is tied to a dock. As you are paddling the resistance is high because you are being held static. Then someone cuts the line and you are allowd to move. You would actually feel less resistance as you paddle.

Joystick TX

I can tell you from my experience that these two lines from w8ye are golden for me:

"A slow reduction of idle speed to a lower value when you close the throttle is a dead give away to the idle being too lean.

A too lean idle will result in the engine failing to respond when you advance the throttle from idle. The engine may even quit."

Print them out and paste them on your field box.

Might be a good idea for Todd to add the sticky info to the engine manual.

Terms like "fat, rich, lean, four-cycle" did not help me much when I transitioned from glow to gas engines. When the engine on my plane would not slow down for several seconds after I chopped the throttle, it was hard for me to believe that it was due to a lean engine. I think I found that nugget a couple of years ago from MtK on the Syssa performance site.

I had bought a used FPE engine and was cursing it every time I tried to run it and thought the previous owner was a crook, etc. Turns out it was a great running engine, not a power house, but it ran like my weed-eater, it only stopped when I cut it off or it ran out of gas. I'm not an expert at adjusting the gas engines yet, but I have been able to fix a few "dogs" for people at our field.

I flew glow engines since 1948 and the other thing I learned was gas engine adjustments are not made in 1/4 turn increments, they are more like screwdriver blade width (thin part) adjustments. The 20 and 30 cc engines have so little fuel going through the jets I'm surprised they work at all.

JeffinTD

Mine is set a good 1/8 turn rich from max rpm on high, and the low is 1/8 turn rich from where it accelerates w/o bog, so at least in my case I don't think the dead sticks are from too lean...

Slow and Steady

Just to clarify, engines can bog down when throttling up if they are too lean or to rich. If lean, they will spool up slowly, or quit altogether. When set properly there is no hesitation during transition from idle. If to rich, they will hesitate from choking on excess fuel and it sounds like it. Your engine still may be lean if your throttle-up response is not immediate. Your engine may also still be breaking in and need a higher idle; I believe the manual lists approximately 2,300 as the low end, although mine is now set at 1,600 on the ground. Also, I don't think mine was fully broken in after two gallons, but I have not had an issue with it quitting in flight. I totally agree with the last several posts, except that engines will overheat, even without a cowl, if to lean.

ahicks

My Feedback: (2)

If it seems to be running OK at wide open throttle on the ground, that pretty much reduces the potential for plumbing system problems to something pretty low/remote. The only other thing that might cause the engine to shut down in the air might be extreme heat? If it's shutting down at lower throttle settings, that's not very likely either....

I don't think you can always judge the low speed mixture by it's willingness to transition. They'll run fine MUCH richer than that.

>>

"really tough to start" has lean written all over it. One flip starts with this and other similar engines are not unusual at all - but they have to have gas available to them.

If "didn't want to idle down well" means that it was hanging on to kind of a high idle prior to settling down where you expected it to be (known as "idle hang"), that's a lean condition as well, especially if it's doing that on final (purring along great, then dropping rpm's very noticably and/or quitting). This one has had quite a few scratching their heads getting used to these things. That's another (fairly positive) sign the engine is lean.

Try it? Go another 1/8 turn rich? Just don't forget to bump your idle speed trim up a bit to compensate. See if that improves things. If it does, but not completely, don't be shy to repeat.

After adjusting the LS needle richer, and bumping the trim a bit to compensate, I doubt you'll be able to tell you made that adjustment - until you get it good and hot in the air and it doesn't quit as easily, or at all.

Regarding your high speed adjustment, if you think you are rich, and it's not burbling in the mid range flying straight and level at partial throttle (1/2-3/4?) - you aren't rich there either.

Slow and Steady

Ahicks, I may have to save (cut and paste) your response for future reference. I totally agree and your clarity is commendable.

ahicks

My Feedback: (2)

S&S, thanks!
-Al

JeffinTD

With the needles set at the suggested starting point it was clearly rich, to the point it would miss. Was still hard to start.

I set the high end 1/8 rich from max rpm. It would die if you tried to idle. Leaned the low end until it would run at lower rpm. Kept going leaner until it wouldn't accelerate smoothly and quickly, and set it 1/8 turn rich from where it first transitions well.

Double checked top end mix.

Once hot, it wouldn't want to restart. I thought starts cold but not hot, likely rich. Tried going leaner and tried richer.

More time on the engine, and it would start hot and would idle.

Not a heat issue, as I'm running with cowl off.

At this point I think the engine needs a gallon or two through it...

Slow and Steady

You have probably already done this, but you may also want to check your plug condition.

ahicks

My Feedback: (2)

I think running more fuel through it is an exellent plan! The problem is you would like to do that with this airframe, right? That means you need to get this quitting thing sorted out/engine reliable?

On the bold, not clear why you assumed it was rich, vs. the possibility that the idle trim was set too low?
If you are experiencing that "throttle hang" described earlier, there's little chance you are not lean on your low speed. Not a lot, but that can be easily dialed out with just a little patience going a tad (screwdriver blade width) richer at a time until that problem stops. It's a pretty common problem, with an easy solution!

hyflyer9

Please keep in mind all that i am using an Xoar 18x8 beachwoodprop and the max rpms are around 7800 without the tone inserts and about 6900-7100 with the tone inserts the throttle response is good and when i throttle down it does take a few seconds for it to come back to full idle at around 2260-2310rpm. and for my 18.4lb War Bird i can use all the power i can get . I will say that i am some what used to tuning gas engines but this engine seems to have a different sound than most other engines i have dealt with. . Also I did find that my muffler was starting to get a little loose and the back plate had actually lost and few screws do to the vibrations . but i did the modification as other have and had it running today on the ground and now is back to a good running state but a few days ago i could not get it to run hardly at all not to mention could not get any kind of tuning adjustments to respond properly do to the loose muffler .

JeffinTD

It doesn't exhibit sag. It also would run fine where I had the idle set (fast) and would then shut down.

I'm hoping that was attributed to air leak in the T, but haven't been able to run it since replacing the T.

Fortunately this airframe is quite easy to glide in. If the wind hadn't have been up today I'd have checked mixture setting again and would have kept it high and up wind and just flown the snot out of it.

I did foul a plug when first getting it to start. I may change it again.

Last time at the field I made slow but steady progress at getting this thing to run, and would have kept going if it wasn't for bubbles starting to show up at the T.

tele1974

What ratio should I be running Stihl Ultra HP at. I run it at 40:1 in my ZDZs. After reading the manual and the DA recommendations I am wondering if I am running too much oil.

w8ye

My Feedback: (16)

40:1 is fine but the Stihl Ultra is usually packaged to make 50:1 convenient

Joystick TX

For those of you who may have a timing problemand suspect thatthe keyway on your crank has sheared, this old photo may help. It is hard to see if the key is sheared just by looking at the hub and crank from the front.

With the piston at TDC, the slot in the hub is pointing exactly 180 degrees from the top of the piston. The magnet is lined upvery closewith thescrew hole.<o></o>

Joystick TX

I run my engine with Stihl Ultra at 40:1 even though it does take some extra effort to mix.

I feel better having a little more oil. There is almost no difference in the amount of oil that is left on the plane after an hour or two of running.

hyflyer9

Does any one know what the noise levels might be on this engine as in db levels at full throttle .
Thank you.

tele1974

I was running the Syssa on a pipe and now its in my pattern plane on the pitts muffler. And wow its loud! Other then the tone inserts is their any muffler mods that can be done? And is the new muffler quieter. Sorry if this has already been talked about... its been a while since Ive been on the thread.
I dropped it in my newly recovered Great Planes Venus II.

Joystick TX

The soft mount by MTK should help a little.

I have not heard of any other mods.

 I'm not sure if the new muffler is quieter, I think the tone is a little lower.

BTW - You did a fantastic job with the recover.

Joystick TX

I have seen quite a few posts of 96 db using the AMA measurement method. Not sure if the new muffler will be different by any significant amount.

At our field, the noise levelfrom the DLE, withoriginal muffler,and Syssa seem about the same, the Syssa seems to have lower frequency harmonics.

JeffinTD

I've got the new muffler w/o inserts, and it is quite loud.

hyflyer9

I did some noise level checks today and was getting 96db at idle and 111db at full throttle a little noisy for this part of the woods . Has any one ever tried to pack the muffler with glass or steel wool to see if it makes a difference or not . of course the problem there is how to keep the packing from getting into the engine .

tele1974

I'm IN! Will a glass pack work and how do I do it. I got some more flights and the Syssa on the Venus is a great combo. Minus the rap. Guys at the field were saying it was weird hearing a gas engine on a pattern plane. I can't wait to hear the comments at contest this year. I know I'll be the only one running a gasser. .

So what do we need to do to turn this Pitts into a glass pack? In thought about putting 90 degree tube angle on and using some snuffleds but I don't want the extra weight.

Joystick TX