Well, I just pulled out my BME manual and it says to turn the ignition on with the choke closed at idle and flip (ccw) till the engine fires, then take the choke off and flip till it runs. (3-5 flips)

I have always started 2 stroke engines this way, even my weedies.

Being a musician by trade, I switch on the ignition when choking. No mystery when she's ready. If the fuel line is visible and it's clear, than that might be a different story.

Since that starting method was mentioned, i figured i should try to to be better educated. On all of my gas, motors i have just choke with ing. On and when i received my pop, i would remove the choke and flip until the motor started. You know right now i am checking all angles. I was surprised when the method worked so well. Things that make you go hum....

Tim has provided a lot of BME knowledge as he has always done for me with BME. I have been out of the hobby for over a year so sometimes you need to hear things over again along with trying new things to see what may have changed in the hobby while you were away. No pyridine here. I am back from my evening out on the town with the wife seeing 40 year old virgin (good movie) and chilies eating so tomorrow i will know a little bit more. I am hoping going in on the low and moving the throttle servo trim will achieve a 1500 idle that will not drop in my 20-30 seconds period...

Geist, I'm thinking (uh oh, here's trouble!) that your problem is different that Krazyc's problem. He doesn't have stable idle on the ground, rather, it will "hang a long time on high idle" then will suddenly drop 300+ rpm. OTOH, your idle on the ground was "very consistant without any changes" but that you had a higher than desired idle on landing approach until the speed dropped. Two different issues.

That's why I suggest that Krazyc might have a mixture problem. He did state that when he richened the mixture there was a point the idle improved but that he had transition issues, so he went back to the "factory" low speed needle setting. I'm thinking if he had leaned the high speed needle a bit , the transition would have cleared back up and he would have been fine. BTW, I'm not ruling out an small air leak somewhere that affects idle much more than full throttle. Whatever the cause, it seems to me a real possibility that engine is telling krazyc that it's low speed is too lean.

Taking a huge risk trying to have two thoughts in the same hour, I'm thinking that the reason your landing approach idle rpm varies is because the prop load also varies. In the pits, we set a low idle and the prop is slightly loaded, pushing air. On your landing final approach, airspeed removes this slight load, thus the idle rpm rises a bit (the same thing happens on a larger scale when the plane is on a downline with the throttle at idle, but the prop rpm increases as it is actually being driven). As you said, "it just idles fast until the speed drops down". Get to stall speed, the slight prop load returns, idle rpm drops a bit. Mine does the same thing, and it's not unique to the brand, it's a prop load thing. The prop isn't actually pulling, it's just windmilling, and not contributing to drag, so the plane takes longer to slow down. Drop a couple clicks of throttle so it's not windmilling so much and the airflow is doing more to turn the prop, then the drag increases so the plane slows down better. When the prop load returns at touchdown, it might take a click of throttle lever to keep the engine running for the taxi back to the pits.

I used to be the same way, untill a Sachs 4.2 "smacked" me hard. [sm=spinnyeyes.gif] I learned.

I now always choke with ignition on!

Krayxc, I'm no expert by any means, but I do have some procedures that have worked for me. One thing I have noticed about most model airplane gas twins is that the carburetor does not meter fuel well at all throttle settings. We're using carbs that see duty on chain saws and weed eaters, and those applications only require a decent idle, and a decent full throttle. Most giant scale plane flying is at part throttle, where the carb doesn't do well. We're forced to compromise and this is why one usually hears a big twin that idles well, and pulls well at full throttle, but exhibits a slight burble a part throttle settings. We need a richer than required setting at part throttle to insure enough fuel at full throttle. I have heard big twins that were smooth and leaned down enough so they didn't burble at part throttle, but, for the most part these engines also didn't pull as well, sagged slightly on uplines, and ran a bit hotter that other engines.

The next thing I've noticed is a difference in tuning glow and gas. On glow engines the low speed needle is only effective up to almost 3/4 throttle during which the high speed needle setting makes no difference. The high speed glow needle takes over at 3/4 to full throttle, during which the low speed needle setting makes no difference. On the other hand, a gas motor with a Walbro carb has a high speed needle that starts to be effective at less than 1/4 throttle, and the low speed needle is effective at ALL throttle settings. Any change you make to the low needle setting affects the engine at all throttle settings. The Tillotsen carbs that some 3W engines use does a better job at part throttle settings but even it is not perfect.

Armed with those facts, the way that I tune my carb is to first understand that the so-called "factory" settings are not the ideal settings for the engine, rather are simply settings that will allow the engine to at least start up and run. The best settings take into account your region's temperature and humidity, altitude, prop choice, airplane characteristics relative to speed, drag, etc. You must listen to the engine tell you what it wants.

Starting at the factory settings, turn the high speed needle to peak rpm at full throttle, then richen to a 200 rpm drop (maybe 1/8th to 1/4 turn richer on the high speed needle). Now, after revving the engine up to clear it out, throttle to idle and adjust your low throttle trim to get a low idle, say 1,700 rpm. After 10 seconds quickly advance the throttle. If it burbled briefly and then cleared out, you know it's rich, so you lean the idle needle 1/8th turn, rev it up to clear it out, and try again. The rev it up and clear it out part is impoortant, because if you don't it fouls the next test. After several "tests", you'll reach a point where the burble is less and less, and you'll need to lean the needle in 1/16th turns rather than 1/8th turn. The idle needle is very sensitive as it gets close, and it's easy to over shoot the mark. You'll know you've gone too far when you advance the throttle and it doesn't burble, rather it hesitates kinda gasping for air, then revs up. You then richen the idle needle in 1/16th turn increments, until you get the stable idle you want, and the transition response you want when you open the throttle. You then check your full throttle again, because leaning out the low speed needle also leaned out the full throttle. You adjust the high speed needle to get the full throttle peak, then richen the high speed needle a bit more so that the full throttle rpm drops 100-200 rpm. Go back and check the transition and adjust the low or high speed needle to suit.

All this is time consuming since you can't make the adjustments with the engine running, rather you've gotta run a test, stop the engine, adjust, fire it back up, CLEAR IT OUT, then run another test. As you can see, just like in a glow engine, the MAJORITY of time is spent adjusting the low speed needle, and you listen to the engine tell you what it wants. The above assume that the engine was rich at the first test. Obviously if it's too lean, you open things up until it IS too rich, then creep up on the proper leaner setting. If the low speed needle needs to be opened up more than maybe 1.5 turns to get an idle, I'd look for an air leak somewhere. BTW, I'm assuming you're using the stock mufflers, right?

I'm sure nothing I've said is new to you, and on the top end, your engine is turning about the same 6,300+ rpm my 102 pulled with the Menz 26x10, if memory serves me well. Hopefully, that idle will come on in for you.

Bummer

I just finished cutting the grass and while all sweatee I know its time to check out the motor. I choke the girl and three flips later, I had my pop. Choke off and three more flips and she is running. The ultimate carries 2 degrees of down thrust on the stab so starting her she tilting forward hitting the grass. I did not think anything of it I went on with the testing. I am getting 7800 RPM out of the high and 1800 on the idle overall instance throttle accelerate just a slight burble. I am thinking man these cheap tacs keep letting me down. Upon cutting it off, I see I have been running for about 45 seconds with a broken prop. I am out of the show until I can get on the phone and find me a Fuchs, rcs, msc, mejzlik to finish my testing. Here are the pics below.

Sh$t happens sometimes.

Geistware

I received the invoice today for a mejzlik 26 x 10 prop. Its from Model Flight located down under, As soon as the prop arrives I will go back to testing. any changes on your end with your needle?

ps the prop was 55.95
shipping 7.00
total 62.95

Da sells this thing for 66.00 less shipping

Hey there, I have a BME 102 and I hab a factory ignition on it but wore it out. It never kicked back, ever! After the old ignition was replaced with a new sychrospark from c&H mine started to have a slight kickback on the start as well. I am SURE it has to do with the timeing. It has never bitten me but I have errored on the safe side and use a stick. If you figure out the problem let me know.

Kinda nervouse when starting,
Tony

Thanks,
I will see if they have any more.
Turning the needle in 1/8 turn gave made the engine run a lot stronger.

Just purchased two from them
Thanks for the heads up

ok ya'll BE CAREFUL. Sometimes this will help an idle problem. Proced at your own risk....
Look at the butterfly in your carb, some have a hole or a small notch in the butterfly. Check to see if the notch is in line with idle jets. If not solider up the old one and use a triangle file to cut a new on inline with the jets. If your carb has a hole in the butterfly solider it up and make the notch in line with the jets.

Geistware
glad to hear she is running strong along wth getting those props i think i will start dealing with this company that i ran accross by using google. speaking of google try this:

1. Go to google.com
2. Type in the word "failure"
3. DO NOT click search
4. Click "I'm Feeling Lucky" (the tab right next to search)


ok the prop arrived safe and sound today so i should have some testing in Saturday


Ps I have been using my heavy duty chicken stick after i felt it was a good thing to have fingers



Tony Bro

yeah that shows what we are thinking if you ask me that box is passing the test but it must be very close to not passing at times

well i need to drill the back of the hub out just a little 7/16 i think so that i can mount that prop. i may go to thesse carbon fiber deals as the grass always starts nipping at my wooden props. I don't 3 d as much as i use to so i don't think i will miss any spool up factor

That was kinda tight.

Interesting [8D]

Kick Backs --> A few months ago I had a slightly used engine start to kick back on me. It kicked hard, and often.
I also tried a new and different ignition with the same results.
I bought this engine new, and broke it in per the manufacturers instructions.

I finally sent it to the dealer for a look.
I'm not as good with gas yet, as I am with glow.
The dealer determined that the pistons were carboned up enough to cause the symptoms I was having.

He cleaned the pistions and replaced the rings.
When I got the engine back the pistons were indeed cleaned, and the rings were new.
The dealer never did tell me why, or even mentioned that the carb was changed also.
I knew this because I keep a log of things like that.

The engine is now fine, and I stopped asking questions.

Good luck_bob

bob_nj

I keep a log of all that junk to it helps me when i have been away for a minute to recall what ever that log book tells me

Don't get old!

Between computer radio set ups, switches, programming and the like, I need a wrap sheet on every plane.
If I've been away from a particular plane for awhile, I'll sit down and review before I get back into it.

Is it just me[X(]

I only fly one plane at a time. Never have more than one ready. The up side is that I usually get a lot of flights out of planes. The down side is when I have a mishap, I am down for a while until it gets replaced.

I'm with you Geistware. When I go to the field, I have either one 35%, or one 40%.
There are flyers who show up with three and four planes, and fly them all.
Personally, I can't do it that way.
The more I fly one plane, the better I get to know it.
Like women, they're all different.

This summer I've been flying a 35% Edge. Since I'm breaking in the engine, that's
all I've flown since June.

Just my opinion_bob

we have use to have a flyer that bought his big boy every week but only flew the small jobs lol

Today testing started good. Easy start up, I am getting 6500 cold on the RPM 26 x 10 Mejzlik the engine is idling about 1500 and slowly creeping down to 1000 RPM. Once I have killed the motor to do some adjusting, here comes the kick back again. I then cut the back out of the cowl to make sure i can rule this thing out. Now the little ignition thing comes a loose on the motor. Well just is finished for today and i am not feeling this motor problem to say the least. I guess this would have been a lost plane in the t-roll with the wire coming off the ignition.

Krayzc
Looking at yer pics makes me ask - Where are your air baffles to direct air over the cans? Also have you looked into your pop-off pressure for your idle issue? Just my 2 cents.

Here is a link to a post that where I listed some references for parts, and a pop off explanation for those who are interested.

I can't figure out what the link in the last post is supposed to do though[]

[link=http://www.rcuniverse.com/forum/m_1866098/anchors_1866098/mpage_1/key_pop/anchor/tm.htm#1866098]pop off[/link]