This is my first gas engine and first flight on it. I started it and ran 3 tanks of gas through it on the ground. It ran great I never mover the needles from where they were. Today when i i went to fly it. It ran great but sagged alittle on verticals and inverted flight. After about 4 min. It lost alot of rpm, I could not even hold alt. I landed the engine was very warm. Not knowing alot about gas engines I am wondering if it is overheating, or maybe it is an airflow problem to the carb(the carb is all inside the cowel) or is the mixture just not set right.
Thanks for the help
Bill

If it lost that much power it was way too lean..Better take the cylinder off and check for a partially stuck piston.....You're lucky if the piston is still good......
The needles are there for a reason..You should set the high needle a little rich on the ground to allow for the mixture to be correct when the engine speeds up in the air..NO MANUFACTURER CAN POSSIBLY PREDICT THE CORRECT NEEDLE SETTING FOR EACH INDIVIDUAL PROP AND ALTITUDE. It's just an educated guess..The best they can do is try to get it rich enough so the engine will not be too lean the first time the customer runs it....
If you start with the needle 2 turns out and lean if from there, set for max rpm and back off about 300....
Good luck with your cylinder and piston.....

Rcign

Thanks for the reply. I know that the mixtures need to be used. It was just running so well on the ground I could not bring myself to move them. I am wondering If the piston was shot could I still turn it over. It turns over fine and is not tight at all. I also did not mention but I flew it twice and the same thing happened about 4 min into the second flight. I really hope it is as simple as riching it up. Also there was a good amout of oil on the bottom of the plane.

Thanks agian
Bill

Sounds OK..Try richer, also check your battery..Sometimes a battery will look good but if one cell is weak it will lose enough to make the ignition erratic.....glad to hear your piston and cylinder are still good....

Try listening to your engine -a bit more carefully- if it EVER sounds like the rpm drops -especially on climbing- it is a fair bet it is too lean.
Also - if you have not yet learned to do so -- move the throttle stick to various positions as you fly - let the engine change temperatures .
ALL of these engines need a breakin period -.
Breakin needs the engine to change temperature (within normal heat range) as you fly.

What prop are you using on the engine? Brand of oil and ratio? Reason I ask is I've had a very good experience with the BME, but was careful to do everything by the book.
I'm running a 22x10 now, and I'm on the fifth gallon, and going to synthetic oil after this gallon.
I can tell you straight up the things got power, and just keeps getting more powerful. Sorry to hear yours is having situations.

What kind of RPM readings are you getting on the ground?
Brand new first 10 minutes of it's life I got 6300r's, it slowly crept up and is now at 6700 to 6800 with 22x10. I ran it on the bench though for about an hour before installation, carefully monitoring time and heat, with the first few runs being 3-5 minutes, increasing time every run, until I could comfortably run a tank empty...it only took about 3-4 full tanks and I had no question it was ready for the plane.

Also..something different from glow is, the tank vent does not go to the muffler! The tank vents out of the plane wherever you can get your vent line decently routed. So the tank vent is always open. Just route it up,,,then down somewhere, usually around the firewall area.

Then I did just as dick hansen is telling you...vary your throttle positions, to get a full range of RPM's.

Airflow is very important too...is your engine cowled in? If so, is there adequate ventalation? Meaning air in....and air "OUT" . Reason I ask this is I've seen installations that are beautiful from the front, but offer little to no escape for air that comes in, hence...no flow.

You should have as much or more area for air to escape the cowing, as you do air-entry. So that muffler exit and even other parts of your cowling, should really be alot bigger then your air entry-way to offer the flow.

Another suggestion is to pull it out of your plane, take it back to the bench and run some tests on the bench, pretty much as we've said here. This way you won't endanger your plane, nor your engine. It's alot of $$$, and you might want to be sure. Starting over kind of.

I do hope this helps...look forward to hearing from you.

ok guys

I took it out today to just run it. I turn the high end needle out 2 turns and the engine still ran fine at full power. It was out about 2.5 turns before it started to lose rpm. I then started turning it in got a peak rpm of 7100rpm with needle at just a little in from 2 turns. I backed it out ran it up agian and got 6800 rpms. I am now out about 2.25 turns on the high needle. I also turned the low end in just a touch. Is it normal to be this far out on ther needle?? Should I give it a try in the air?? Last time it lost power but at least did not quit, and i don't want that. I am using a zinger 22-8 prop.
thanks for the help guys
Bill

You are in the ballpark with that needle setting. It is all dependant upon your climate. When an engine is new you are ALWAYS better off to run it a little rich, so continue to find the peak RPM as you have done and then richen it a LITTLE. NOW GO FLY, maintain enough altitude just incase. Since you have had this issue, I would fly like this until you feel it is safe to get down and dirty with it. Take it easy a log some time on that engine. As it breaks in you will need to adjust the needles some more.

Keep in mind I said a LITTLE rich. You do not want to maintain a rich setting for too long as carbon will start to build up in your engine.


Jeff

check out the previous comments - then go fly - and listen - At this point in learning about your engine - the important thing to remember is that it needs some time to get properly seated -
Don't fret over the rpm - it will change -
you probably have heard the sound of the engine when you were peaking it -and noted that running it too lean, it sagged and the sound changed
Be prepared to land the model if it appears that it sags at all when climbing -or at anytime in the flight.

Yep,,, at this point I agree she's airworthy. You've got some good numbers on that engine too.

As everyone said though keep a safe altitude, and listen to that engine. You should hear a sag if it's lean, if that occurs land immediately and richen it, then try again. This is about all I know here...patience though will prevail...if it takes 10 times to get it right..well..it will be right. Good luck.

Another thing I would like to say and you may not totally admire is........

Unfortunately, we all have to learn how things work and sometimes we have to learn the hard way, by mistakes. So even if, if, your engine has suffered minor damage, you need to chalk it up for EXPERIENCE. Continue to listen to what people may say in this post and you will learn, as we all do.

Run it and listen too it. FEEL it. if you can or if you have a buddy that can, check temps, tach it frequently and literally take notes. Look for any negative changes, and if it starts to look as though the engine is burnt, CALL KEITH BAKER. Tell him what happened. He is an excellent guy to deal with and I am sure he will be able to give you worst case and best case scenarios.

If you had plenty of oil on the bottom of the plane after the run, then I doubt that you hurt it too bad.

DO NOT GET DISCOURAGED


Jeff

Thanks guys

I understand this is a learning process. I am so glad for this forum, because I think it will save me lots of money on this learning process. Thanks agian

I am going flying right now
Bill

To all,

What brand product do you use to check engine temperature?

What is the acceptable temp range for the BME 50 and/or similar displacement gas engines such as the Taurus, Brison, and FPE?

Thanks for any info.

____________
jmboss