Rebuilding GSM026's BME-115

[KrisW]

So. . there I am, staring down at this 300 lbs lathe. . trying to figure out how to get it up onto the Bench without giving myself a hernia. . . getting it out of the van and into the shop was one thing, involving a bridge of 2X4s from the bed of the van into the doorway of the shop, and lots of tugging, pulling, and a bit of sweating. .but now it has to go UP THERE!!!!!

I actually surprised myself, and didn't wind up in the hospital. Ever see that series of pictures of the Chimpanzee stacking boxes to get the banana hanging from the string? Same principle, except it involved an old 75 lbs super heavy duty coffee table that had the finish worn off it, some 2x4's and 4X4's, and about 1/2 hour of grunting, sweating, and wondering when I was going to have to call the paramedics to take me to the hospital.

All I have to say is. . SWEET!!!!! and the Mill looks pretty nice too. . . .

Cutting bits and impliments of destruction will be here shortly. . then the metal chips will start flying

Got me some engines to build. . . . .

[RTK]

Don't forget the pictures

[KrisW]

	Quote: Originally Posted by RTK
	Don't forget the pictures

Of my broken back, the machine tools, or the engines???

[Hammbone]

Kris,
Your "fix" for the BME 115 does not work for me. The engine is running better, in fact the best it's ever run, but still far from dependable / acceptable.
It still burbles and looses rpm's when inverted (though not as bad as it used to).
It still hesitates and makes you think it is going to die (for no apparent reason).
It still does die in flight. I had 2 (out of 3) dead stick landings.

First thing I did was run it at your settings. I did not touch the needles. The results were as stated above and my first dead stick of the day.
Then I tried leaning the low end a little, but it would not transition any more, so I put the low end back to where it was and leaned the high end. Still would not run right in the air. Just to be sure, I also tried richening the low end, and the high end, but no luck.
The engine is still doing all the bad things it used to do, just not quite as bad as it used to.

I can only guess that this is because I fly at 5,000 feet altitude. I believe that it ran good for you, but it is definitely not running good for me.

Just thought I'd let you know.

I'm gonna have to see what the new BME owners have to "fix" the BME 115.

Thanks for trying, Jim

[KrisW]

	Quote: Originally Posted by Hammbone
	Kris, Your "fix" for the BME 115 does not work for me. The engine is running better, in fact the best it's ever run, but still far from dependable / acceptable. It still burbles and looses rpm's when inverted (though not as bad as it used to). It still hesitates and makes you think it is going to die (for no apparent reason). It still does die in flight. I had 2 (out of 3) dead stick landings. First thing I did was run it at your settings. I did not touch the needles. The results were as stated above and my first dead stick of the day. Then I tried leaning the low end a little, but it would not transition any more, so I put the low end back to where it was and leaned the high end. Still would not run right in the air. Just to be sure, I also tried richening the low end, and the high end, but no luck. The engine is still doing all the bad things it used to do, just not quite as bad as it used to. I can only guess that this is because I fly at 5,000 feet altitude. I believe that it ran good for you, but it is definitely not running good for me. Just thought I'd let you know. I'm gonna have to see what the new BME owners have to "fix" the BME 115. Thanks for trying, Jim

I'm curious how far you leaned the high end, since it was a tick rich when I sent it to you. The engine will tend to cut off if you lean the low end too far, because there is no place in the crankcase for fuel to puddle, wo you have to be SURE to get the mixture fat enough on the low end that when you throttle down, then back up, the engine has enough low end mixture to not go over lean. Judging the thin air where you are, I'd go a lot richer on the bottom, and tune the top for clean running on the ground, especially from mid-high throttle.

I'm not going to pull a Keith Baker and say it's perfect, but it WILL take some tuning on the needles to get it to work at your altitude.

Deadsticks are caused by overly lean conditions on the idle side of things. Get that straight first, make sure you are clean on the top end on the ground, and it should run properly.

As for roll over burble/sag .. sorry . .I'm not buying it. There's no place for fuel to puddle, so that condition IS eliminated.

As for any new "fixes" the owners of BME will come up with, they probably won't be able to improve on what I've done. Not saying my work is the last word, but there is no further improvement that can be made for the inlet tract unless you ditch the larger carburetors and go back to the SDC-80's.

[Hammbone]

	Quote: Originally Posted by KrisW
	As for roll over burble/sag .. sorry . .I'm not buying it. There's no place for fuel to puddle, so that condition IS eliminated.

I'm not making it up, it is still doing it, whether you believe it or not.

I didn't move the needles much from where they were. The most I moved them was maybe 1/8th turn either way. I will try richening the low end more and leaning the high end as you suggest.

Jim

[KrisW]

	Quote: Originally Posted by Hammbone
	I'm not making it up, it is still doing it, whether you believe it or not. I didn't move the needles much from where they were. The most I moved them was maybe 1/8th turn either way. I will try richening the low end more and leaning the high end as you suggest. Jim

One thing to remember, Jim, it's NOT going to sound like a sewing machine at low throttle settings, no matter what you do, especially on the low end. Give the engine the fuel mixture it needs to RUN, and toss public opinion out the window for how it sounds at idle-1/3 throttle. I've been pretty specific about this in the instructions I give everyone, especially about the need to go leaner on the top if it was stumbling and sagging at 1/2 throttle and up. In thinner air the bottom is going to tend to go lean, and you have to compensate. If you don't then the dead sticks you are experiencing are just going to continue.

To set the needle for the bottom, make SURE that coming off a long down line at closed throttle, after the pullout and when you throttle up that the engines does not sag at all. If it sags, it's too lean. It may sound a tad rich at idle-1/4 throttle, but because of the radical porting every 115 is going to sound that way. There's really no way around it. The top end should sound crisp and clean from 1/2 throttle and up, If it sounds rough, it's too rich. Do NOT go richer because you will just make it worse.

Do NOT lean the bottom for a silky smooth idle. It's not ported for that, especially with innefficient diverters, and you will get deadsticks. If the DA guys complain, tell them to go eat something nasty from the latrine.
Do NOT richen the top end if it struggles to get top rpm or is rough at 1/2 throttle.
And if it sounds a little rich at 1/3 throttle, that's normal. It's supposed to do that and you will never get rid of it.

It's that simple, and it can be adjusted for your altitude.

[ben_beyer]

I used to fly with Jim and the club has plenty of "should've bought a DA" guys in it. I like DA and have nothing against them, but some of their die hard fans are annoying.

[Hammbone]

The DA guys don't bother me, and have never said a negative word to me. They know better.
I'm not worried about what the DA guys think, I would just like to get this engine running good.

Jim

[KrisW]

	Quote: Originally Posted by Hammbone
	The DA guys don't bother me, and have never said a negative word to me. They know better. I'm not worried about what the DA guys think, I would just like to get this engine running good. Jim

The engine runs "Great" Jim. All it needs is a little finesse with the needles for your altitude, and an understanding that what you think is "good" is going to be a bit of a compromise with the exhaust system you are using.

Things to remember when tuning.

Idle -1/4 throttle is ALL low end needle
1/2-top end is ALL top end needle
Transition from 1/4-1/2 tells you how sensitive your top end is and gives a good indication of how rich, or lean, your top end needle is. If it's slobbery at 1/3-1/2 throttle, it's a pretty good chance that your top end is fat. If it's all pretty and clean, more than likely you are too lean on the top. If it is a little rough, but transitions well to top end, you are pretty close to perfect.

Don't get them backwards. On this engine you don't richen it to get better transition, you lean the top end because the top end circuit in the carburetor comes in very early and will flood things above 1/3 throttle if you richen things up.

[RTK]

Exactly correct Kris. I have been telling people to richen the low and lean the top to remove mid range burbling when rolling. You do not set the needles on this engine as you do most others. With the reduction of fuel puddling area it should just be a matter of getting the needles right.