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Help getting my BME 50 to run?

Old 05-26-2004, 07:32 PM
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NE0
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Default Help getting my BME 50 to run?

I started running my 50 in last night on my WH Edge, and have a few questions...

We tweaked the needles per the instructions and got it to idle very smoothly at around 1350 RPMs. We peaked it at about 6650 RPMs with a BME 22*8 prop, then richened it back to about 6450. Transitions are good, starts very easy, all "seems" great. But I have a couple strange things happening...

1) When the engine is run up through the mid and high range a couple times, then brought back to idle, it "hangs" at about 18-1900 RPMs for 25 seconds, then falls suddenly back to a smooth 1350 idle. This happened pretty much every attempt and revving the engine. It idles great at 1350 when it gets there, but takes 25 seconds to level down to that speed.

2) When you try to run the engine at about 2000 to 2300 RPMs, it "porpoises" between 1900 and 2400. It just sits there surging/porpoising through the 1900-2400 range non-stop like a roller coaster. It stops as soon as you go above or below that throttle setting.

I'm using 87 Octane regular gas mixed 32:1 with LawnBoy Ashless, running a BME 22*8 prop and the cowl is not mounted on the plane right now. We tried "blocking" the carb from the prop wash with our hand while running and it didn't seem to make any noticeable difference. I've ran about 18-20 oz of fuel through it so far.

I was very impressed with how easy the engine started right out of the box, and it seems to have tons of power. It's just these two anomolies that have me concerned and I'd like to work them out before taking the plane up.

Any advice would be greatly appreciated.

Thanks,

Tom
Old 05-26-2004, 10:15 PM
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Default RE: Help getting my BME 50 to run?

if it makes a burbbleing sound at half throttle try leaning it out on low end just a very little bit but it sounds like you may be a little lean on low end i would say no burbble then richen it up just a little on low side
Old 05-30-2004, 02:20 PM
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Default RE: Help getting my BME 50 to run?

Thanks for the response, but it turned out to be a bad CH ignition module. Changed it out and it runs much better now.

Tom
Old 05-31-2004, 11:00 AM
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Default RE: Help getting my BME 50 to run?

Tom,

How did you discover this? Might be usefule for us other BME owners. Did you have anotehr obe to swap out?

mark
Old 05-31-2004, 06:39 PM
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Default RE: Help getting my BME 50 to run?

Yes, I have two BME 50s... which I feel like throwing out the window right now! [:@]

It's not the BME's fault, it's just that I am not a mechanic and I don't have a clue how anyone gets gas engines to run right. I had it running "so-so", put the cowl on it, took it to the field and it won't run right at all now. I can't get it to hold an idle below 2200 RPMs for any length of time anymore. The surging seems to be gone, but it just won't idle for crap.

I've been leaner, richer and every where inbetween so many times I could shoot someone and still no luck. I think I'm going to take up stamp collecting.

Tom
Old 05-31-2004, 08:45 PM
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Default RE: Help getting my BME 50 to run?

OK, looks like we've finally got things working now. I had my best friend Dave take a look and he was concerned about some "flex" in my throttle linkage. I got rid of that problem and then let him tweak the carb needles for me. I think he was right that the flex in my pushrods was stopping me from getting any consistent readings from my engine. Once that was eliminated, it was really a matter of going by the numbers until we got it running right.

Now the engine is idling (with the cowl on) quite consistently at about 1600 RPMs... with an idle-down setting that runs pretty reliably at about 1350-1400 RPMs. Transitions are very good and I'm running the top end a little rich at 6600 RPMs. It can peak at just over 6800 right now, so I'm going to leave it at 6600 for the first couple gallons, then lean up the high end later.

So far so good... hopefully nothing will change when I take it to the field... you know how those RC gremlins are!

Tom
Old 06-01-2004, 07:49 AM
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Default RE: Help getting my BME 50 to run?

BME quiting, my freind and I have 2 of thease, mine is in a box ready to send back, They told me CH had a recall on the ignition, only someone did not tell us. WE thought it might be ignition so we bought a new one at $110, still stoping. The motor runs strong when it runs, but will stop right now seems to be when it get to a certain temp. Will see how there Customer service is.
It seems there test of thing are left up to the customer, it has cost me one aircraft already.
We have had a number of gas motors over the years so you can discount it our fault.
I like the weight, the power is great, when the motor would run it was fine, But only had one flight whare we landed with it running.

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