I purchased a used Wild Hare Extra from a friend and it flew 30 times without a problem. Today I went out and the engine sounded and ran terrible. I could not fly ineverted at all and it seemed to be running hot. Temp after a 5 minute flight was 238 were the plug goes into the engine and 220-240 on the middle of the cylinder. Is this too hot? Some have said yes, and some have said no. I took the plug out to see the condition, and the electrode was white indicating lean, I think. So I tried richening up the high side and no change in running or temp. I then richened up the low side and the idle became very erratic, sounded like a car with a surge problem. This is strange becuase it has flown so well. I am going to get a new plug but I am lost. Then I set both mixture screws back to were they were when it was flying good and the thing will barely idle. Any ideas??? I kind of got frustrated and just gave up for today, but I really enjoy flying this bird so I want to get back in the air but it stinks to think that every time I pull the throttle back it could be a deadstick. Oh yeah the problem seemed to be really evident at idle and at half throttle. It is a BME 50 and I think it is approximately 2 years old.


Tom

Tom,

Yep, a white plug is lean, it sounds as though there is dirt in the carb. Take of the plate on the same side of the carb as the fuel inlet. Right where the fuel inlet comes in is a very fine mesh screen. My bet is that screen has some dirt in it.

Clean the screen and set the needles to factory specs and retune

YOu could have an air leak as well but I'm betting on dirt in the carb

BTW...I never run a gas engine over 200 degrees and love to see 180 to 190. At 230 degrees it will not take long to toast the cylinder and ring and by long I mean a tank or two

Thanks Bubba. There was more then one piece of dirt in the carb screen. I wish I knew how it got there. I have a filter on the tank and on the plane. What is the most efficient way to clean the filter. There is more dirt in there and I want it to be completely clean. Also, how big of a piece will cause this? I mean there was a pretty good sized piece in the hole were the filter is, but it was not that big. I guess this has to be it though. I don't know.


Tom

Tom here's my 2 cents. Your temps are not to high, but your plug reading is indicating a lean condition and/or a hot run in the air. Not to be argumentative bubbagates. I have in flight temp'd a few engines and they will hit 300+ when running hard. Tom, I assume you took these temps after landing and that number is just a "best guesstimate" number, but you sound in the ball park anyway.

Be sure and check your fuel system all the way from the clunk to the carb and make sure there are no leaks, etc. Make sure there are no air leaks in and around the carb spacer too. Next I would go to you local saw/lawn mover shop and buy a rebuild kit for the number on the side of the carb. Take your time if you have never done this before and do one side of the carb at a time noting where which way and where all the parts came off.

Edit--Just read that you found a blockage in the screen, that might be your problem and I would try and run it before rebuilding the carb. I always filter from my fuel jug with a small in-line automotive paper filler and don't seem to run into problems with crud in the screen.

Thanks RTK. I did find a pretty large piece of foreign material in the carb. This plane has some mileage on it and what really puzzled me this morning was how good it was flying and then all the sudden how bad it ran. I will try and run it again, now that the dirt is out of the carb and see what happens. I might be a little sensitive to temps but I was curious so I am using a lazer thermometer to take my readings. What concerned me also was that a guy at the field today had a DA-50 in the same airframe, and he flew for about 7-10 mins and when he came down his was at 190-195. No this was a two day old motor with 4 flights on it but I kind of think that I should be closer to that temp. I am also still new to gassers, so this whole thing could be my ignorance in the gas arena. Hopefully this will take care of it. Thanks for the advice so far.


Tom

Sounds like you are on the right track, the only other possibility could be your ignition taking a dump, but it does not sound like that. I think you have already found your problem.

200 degrees is not high. 250 degrees is not high. High is when you reach 165 to 180c, or between 329 to 356 degrees f. At those temps the engine is indeed too hot. That's why temp guns are next to useless. You cannot obtain a useful or accurate engine temperature. If the engine is running below 200 f it's probably running much too cold. Most engines do not reach a useful and stable operating temp until they obtain a minimum of 80c, or 176 f. Below that point ands you cannot set an idle speed that will be the same when you land, or a correct mixture setting. Limiting the engine to 200 degrees provides an extremely limited operating temperature window (24 degrees f) that would be nearly impossible to achieve, especially after adding for ambient air temps prior to even starting the engine.

Well said Silver. I sometimes beat my head against the wall with customers using the lazer temp guns. I can get over 100 degrees in temp readings just by moving the pointer less than 1/2 inch on the top of the cylinder. I am no metallurgist but this cant be possible. Also the brightness of the surface being checked has a great deal to do with the temps reflected. The flatter or darker the surface the more heat it will show and the brighter or shinier the less temp it will read. The only way to know your real engine temps are with a thermocoupler and an in flight temp recorder. All two cycle engines and I dont care what brand they are will run 300 degrees plus when tuned properly. Pulling the throttle back and landing dramatically changes both the temps and the plug color. To check a plug you must run it long enough to establish a color on the plug and then shut the engine off instantly at that rpm and needle setting to know. If your engine is two years old the carb may need to be rebuilt. The neoprene or rubber components get hard over time and should be replaced especially if it has been setting up.

Keith
BME

Thanks for the info. I was observing what you guys are saying about the tempurature flutuations on the cylinder. It just seemed that when a guy at the club flew for about 7-10 mins and the thing showed 30 degrees cooler I got worried. Now I think that the dirt I found in the carb is to blame because of how bad it started running. I am going to get a new plug, retune and if it is still running bad I will rebuild the carb. I did take the gasket out to access the little fuel screen and it seemed nice and soft. I will follow the manual and see what happens, although I feel better about the temp of the engine. Thanks again.

Tom

I have seen 400+ with out damage before. Not that I would recommend it or that it is good for an engine, but if tolerances and materials are right it can be done with out damage. Heck, I have a weedie that has been running 350 and up for about 2 years without damage

I am totally frustrated with this plane. I can't believe I had 30 good flights and now this thing just wont run right. I know it is probably due to my ignorance on how to set up a gasser which is frustrating me even more. So I got a new plug and richened the mixture just a little and now the idle seems too high or barely running. Since I got the piece out of the carb it is running sloppy rich also. Here's how I tried to set the idle. 1) I started the engine and warmed it up. 2) I leaned out the LS needle until a smooth idle. 3) Advanced the throttle quickly to 2500-3500 and this is were the thing just does not seem right. It was hesitating and the manual said this was a lean condition and to richen the mixture 1/16 of a turn until there was a smooth idle and good transition to midrange. I either get a higher then normal idle or an idle that barley keeps the plane running. It seems like if I reduce the throttle trim by 1 click the idle drops too low. I removed the new plug and it is black so I think it is rich but if I lean it there is a hesitation when I advance the throttle to full. Any ideas on how you guys set your mixtures would be greatly appreciated.

Tom

The best thing to do is send the engine and ignition to us. Its unlikley to be fixed over the internet. To ease your pain I will make you this offer. Excluding the ignition and carburetor for obvious reasons along with abuse or crash damage i make you this offer. If you can wear that engine out or if it ever has a mechanical failure on the short block itself I will buy it back from you at the full retail price. I challenge you to find another engine manufacturer that will stand behind their engine like that.

Keith
BME

I don't mean to sound like I am not satisfied with the engine, besides I think it is my inexperience in setting a gasser up that is to blame. I just started flying big gassers and was having a real blast with this plane and then all the sudden the thing started running funny. I did find a rather large piece of debris in the carb screen and thought that would do it. It just seems like every time I think things are going well a setback occurs. I know the engine kicks all form of ass because I had a verticlal that seemed unlimited. I may take you up on the offer to send it in. I'm going to take it to the field tomorrow and see how she runs. Thanks for all the advice and the offer to buy the engine but I want the engine because when it runs right it is a monster.

Tom

Start with the factory needle settings whatever that might be. Will it idle for 20 or 30 seconds without dieing? If so go to WOT for 5 seconds or so then back to idle. When at WOT was it burbling or a clean 2-stroke sound? If it had a slight burble to it, put it in the air and fly it a flight. Does it burble at WOT straight and level flight? If so, land and take the HS needle in 1/12th turn. Fly again. What's it sound like:??? Still got a burble? Take the HS needle in another 1/12th turn. Once you get it to where the burble is gone at WOT in level flight, now work on the midrange a bit with the low needle. Is it really sloppy rich at idle and say up to 3500 rpm? If so take the LS needle in a 1/12th turn.. Fly it again.... You'll never get all the burble out at idle. If you do, odds are you are too lean. Also when you lean the LS needle, you have leaned the WOT mixture a tad. It maybe necessary to go back and open the HS a hair if you close the low very much. Most the time if you're not on the ragged edge of being lean at WOT, it won't be necessary thought. I may catch flack for this, but I never use my tach to set the needles on my gassers. These things change in flight, so you might as well learn to set them by ear and what the spark plug looks like after several gallons. Also don't run at WOT on the ground for more than 5 or 10 seconds...they can over heat in a heart beat.

On the idle trim movement. Gassers can be kind of fickle like that. On my Futaba 8 UAFS transmitter, I can go into the progamming and change the amout of servo movement I get for each "beep" of trim. I can really fine tune it that way......

When testing the throttle from idle to WOT on the ground. Do it like you would when you are flying. How often do you go from idle to WOT in .005 seconds when you fly?????? I've seen some gassers with the carb's set right, that still won't take the fuel when flipping the throttle stick like that....if you try to set the carb to where it will, it won't be right in the air.

Also for a filter in your fuel tank, I use the felt clunk type filters that's used in chainsaws and weedies...I've yet to get even one piece of crap on the screen in the carb.

That is exactly what I'm going to do tomorrow. I forgot to mention no more overheating today. The highest temp seen was 205, so there was a marked improvement there and also the engine seemed smoother at mid throttle. Thanks Frank, I'll post the results tomorrow and if the engine is still running bad I'll send it in to have the thing looked at. I really hope I can fix this though, becuase this is the coolest plane to fly.

Tom

Since you found the debris in the screen, and can get the engine rich now, I'm sure you'll get it figured out. I've found that every engine has it's own personality, and sometimes it just takes a while to figure it out. Be patient on the needle tweeking, and listen to it in the air. It will tell you what it needs.....

Looking forward to hearing how it turns out.

Hey Keith, last question I promise. What are the factory needle settings for the 50? I have heard 1.5 turns on both to 2.5 turns can you please give me an idea.

Tom

If Keith doesn't come back with a reply, 2 turns out on both needles will almost always be plenty rich.....Go 2 1/2 if you really want to play it safe.....At 2 1/2, you're normally maxed out on how much fuel will flow through the orifice.

There is always a learning curve with anything we do, and it seems like you are on your way. When you fly tomorrow start adjusting the needles as recommended and I am sure you will figure out where they need to be. That particular engine is pretty stout and bullet proof. If all else fails take Keith up on his offer, but I think you will be fine without needing it.
By the way, are there any other guys at the field that are experienced with gassers??

I believe that BME will respond something like this. There is no such thing as a factory setting. A good engine tuning STARTING point is with both needles set between 1-1/2 and 2 turns open, preferably at 1-1/2. That is a point where most, if not all, engines will start and the tuning process for each location, altitude, prop size and type, and fuel mix can begin.

Again, there is no such thing as a factory needle setting. Glow engines don't have them and nobody ever asks glow engine manufacturers for "factory settings" What on God's Green Earth leads anyone to believe that gassers have them?

To me a "factory setting" is just that, a SAFE starting point. The engine is not meant to run perfect on these settings. Way too many variables for one needle setting for all.......

There is no such thing as a factory needle setting. A good starting point is 1.25-1.5 on the low and 1.5 on the high. That does not mean its safe to fly it but a good place to start the engine and see what you have. Dont run an engine on the ground at higher thottle settings for more than a few seconds to get a feel for your high speed needle setting. No two engines are the exact same and no two carbs are the same. Throw in prop load, atmospheric conditions, aiflow in cowl, exhaust systems, cooling systems and the variables keep on changing things. What I like to do is fire the engine up, let it warm up a couple of minutes, run up to full power to clear it out and build some heat then come back to idle, goose the throttle and if the engine hesitates or dies its to lean on the low end, if not lean the low until you hear the hesitation when goosing the throttle then slowly richen the low speed needle until the hesitation is gone. I then set the high speed needle to a point that it will not clear out or the engine is four stroking, then lean it a bit until it just wants to clear out to a two cycle burn. It may bounce around a little between two cycle and four cycle. Then you have to fly the plane to let the temperature come up to maximum and listen to the engine. If you hear it four stroking land and lean the high needle about 1/8 turn at a time. Fly and check it again. You should get a bit of four cycle when flying horizontal but when you pull vertical it should clear out and have a good clean two cycle burn. You should tune the engine to pull the hardest on an upline and not worry so much about what it does in horrizontal. I know I shouldnt say this but if it makes you feel any better we have not ever repaired one single burned up 50cc engine. That is saying alot considering 50cc planes are the most common entry level gas airplanes and the BME50 is one of the most popular. Japanese engineer asked me what is difference? House burn down and engine burn up?

Keith
BME

Japanese engineer asked me what is difference? House burn down and engine burn up?

Thanks for all the advice. I just got back from the field and she flew great. I am about a 1 1/4 turns open on the low end and a little richer on the high. Full throttle straight and level sounded rock solid and vertical uplines seemed endless. After full 8-10 minute flghts the highest temp I got was 220 and the engine seemed to cool off quickly once shut down. Also, no deadsticks on inverted flight. I could hear the rpm's go up a bit once inverted, but not even close to deadsticking. Thanks again for all your tips and information it helped a new gas flier more then you know.


Tom

I also pulled to plug to check the color and it is a nice tanish color. No whiteness and not black, so I think she's ok now. Can't say how much I appreciate all your help.

Tom