visioneer_one

My Feedback: (506)

There's a ground braid that exits next to the spark plug cap. I've connected the strap to a convenient bolt on top of the head.

The manual from BME says that the ground strap "must be attached to the base of the spark plug."

I can't see how that would be possible, but I'd hate to blow the ignition if I'm wrong.

Here's a a pic of the mounted engine.


Have I set this up correctly?

LenAlessi

My Feedback: (1)

The arrangement that you have will work - for a while. Then the ground strap will probably break from vibration. It will last a lot longer and probably will not break if you connect the groiund strap to the base of the spark plug using a hose clamp or other type of holding device.

Len

Antique

My Feedback: (4)

Most use a hose clamp around the base of the spark plug..Your setup is better...Makes no difference where you put the wire as long as it's connected to the engine somewhere..If the wire breaks the spark will take the shortest path to ground, through the Hall sensor..It will go bad almost immediately..Looks like the wire is long enough, maybe you could use the hose clamp and then the bolt....

visioneer_one

My Feedback: (506)

Hadn't thought about the possibility of the braid breaking. I'm going to take some precautions against that happening.

Thanks for the tips!

rcpilotjae-RCU

My Feedback: (21)

visioneer_one:

Take it from me, the braid breaks! I switched to the Bosch system to eliminate this.

ZAGNUT

My Feedback: (1)

if you do use the terminal do not solder it! crimp it and put some heat shrink where the braid enters the terminal. check it often!

dave

SMALLFLY-

My Feedback: (19)

I have heard people complain of ignition noise problems with setups like that. I wrap mine around the plug several loops (similar to a shield) and fasten it to the plug base with a clamp. I have had no noise problems with either of my bme 50's

Barry_G

My Feedback: (26)

I see yours too has suffered from the "fragile fin" syndrome. They break like glass!
If you get tired of dorking around with the funky ground wire, C.H. can upgrade your ign. to a Bosch plug cap very reasonably. I've had both and prefer the Bosch.
Barry

Geistware

My Feedback: (16)

I have to agree, the braid will break. Found mine on a range check. (everyone does one, right). I went from abuot 150 feet to about 20 feet. Wanted to fly, but decided not to. I am glad that I did. I would probably have crashed!

birdnest

I have the BME and had the standard ignition set-up (rubber boot, ground braid secured to the spark plug base with a hose clamp) and developed ignition interference after about 15 flights. I found no obvious cause other that gunk accumulated on the spark plug threads, perhaps interfering with grounding. I switched to the Bosch cap with a new plug and store the plane with the engine upright and the problem has not recurred so far.

Peter

GoldenEagle

My Feedback: (1)

I highly recommend sending the ignition back to CH in exchange for one with the Bosch plug cap. They swapped the new (unrun) one of a friend's for $10. Mine cost about $25 to change out the ign. lead and cap because mine had been run. I went through a month of fiddling to get rid of ignition RFI on a BME 50 before trying the Bosch. All RFI problems are solved and you don't have to worry about broken ground straps. All gassers should come with the shielded plug cap to begin with based on my frustrating experience.

birdnest

Chris, I did send the ignition back to CH to check it over and replace the rubber boot with the Bosch cap. It just bugs me that the rubber boot set up worked OK initially, interference developed after a few flights. The only difference I could find to explain the chance was that the plug threads were covered with gunk. The new cap and a new plug seems to have solved the problem but I am still range checking it with the motor running at the beginning of a flying day.

Peter

visioneer_one

My Feedback: (506)

I think I'll just send the ignition in. One less thing to worry about.

rcpilotjae-RCU

My Feedback: (21)

visioneer_one:

If you send in the BME50 Ignition to be upgraded, you can also send in your Hall sensor and they will upgrade that with a better grounding system. I sent both of mine in about two months ago (the ignition & hall sensor) and they upgraded it and got it back to me in two weeks. That's two weeks from the time I sent it out and to come back to me, good service. Oh, and don't forget that you'll need a different spark plug with the Bosch cap, it will only fit the short 3/4 hex 14mm plugs, such as the Champion RCJ7Y or NGK BPMR6A. The Bosch cap will not fit the plug that's in there now used with the rubber boot. They have them in stock too if you want to get them from CH along with the other upgrades.

visioneer_one

My Feedback: (506)

Well - I decided to get at least one weekend of flying in on this plane before sending in the ignition for the upgrades. I added a hose clamp to secure the braid to the plug base as recommended.

Took the plane to the field. Fueled up. Flipped and flipped and flipped and flipped...

Pulled the plug and found no spark.

We adjusted down the gap between the magnet and the hall sensor. Got a mild shock when we switched the ignition on again - I don't know if the ignition fired or if it was just a random pulse of current.

Still no spark.

I'm not sure whether I accidentally blew the ignition or Hall sensor at some point... I've another engine which uses the same ignition module (a TS-52), so I'm going to rob it and see if the BME starts making noise

visioneer_one

My Feedback: (506)

Took another look at the ignition wiring and noticed that the wires into the Deans connectors weren't lined up correctly. ***! I swapped 'em, added some fuel and tried starting it.

I think I'm getting a spark now. Still couldn't get it to start. It did pop and kick back twice - once so hard that it knocked the chicken stick out of my hand and flung it a good 20 yards down the driveway.

I'm wondering if we buggered the timing when we moved the magnet closer to the hall sensor. Naturally there's no mention of the correct setting in the manual...

Any ideas?

rcpilotjae-RCU

My Feedback: (21)

visioneer_one:

If the engine kicks back, that means the timing degree setting is off. That's the beauty of electronic ignitions, once the degrees is set properly it's 99.9% that the engine will not kick back or back fire. Now, the problem is with the hall sensor as this is what sets the timing degrees. Yes, you up set timing when you moved the magnet closer. The reason it doesn't say anything about it in the manual is because you need a degree wheel to set it up properly. CH sells such a kit, but at this point (IMO) I'd send it back to get it fixed and updated. In other words, send the engine to BME to get that straightened out and send the ignition to CH to get that fixed up and updated. Sorry to hear your having all these problems. My BME has been a sweetheart of a engine. Good luck!

P.S. I sent mine in this summer to have a new crank put in. At the same time I sent in the ignition. Both the engine & the ignition took 2 and 1/2 weeks turn around from the time I sent them in. That's good service.

Antique

My Feedback: (4)

No degree wheel needed, there is another way..The distance from the magnet to the hall sensor has very little to do with the timing unless it's so far away it won't work at all...The magnet triggers the hall sensor when it just passes the edge of the sensor..
a hall sensor will work about 1/16" away from the magnet, farther if the magnet is stronger. Most are set up to be about .020 away..
If you want to check the timing take the spark plug out and lay it on the cylinder..Turn the engine slowly counterclockwise until you see or hear the spark..Make a mark on the hub and another directly across from it on the case..Now put the engine on top dead center..Make another mark on the hub..The two marks should be 28 degrees apart..
To find 28 degrees measure the diameter of the hub..Multiply it by .244..This distance is 28 degrees...The formula is case diameter times 3.14, circumfrence, divided by 360 for 1 degree, times 28...Example, case diameter 2 inches, times 3.14 = 6.28, divided by 360 = .0174, times 28 = .488, distance between the marks.....
This works for any diameter, and ONLY on ignitions that use a hall sensor trigger..C&H, RC, Silent Spark, Pro Spark, Air Hobbies, and maybe some others...There is NO dwell time involved with a CD electronic ignition, it fires when the magnet just passes the edge of the hall sensor...The TIM ignitions are not true CD and use dwell time...
FWIW..Timing on these small engines is not critical, a few degrees one way or another makes very little difference...

rcpilotjae-RCU

My Feedback: (21)

RCIGN1:

Who knew? That's why I come to RCU, there's always something more to learn. I agree with you on the fact that a few degrees either way won't make too much of a difference, but visioneer_one's has to be way off for it to be kicking back as hard as he says. It doesn't make much sense to me that it would be that far off either. If he moved the magnet, it shouldn't be that far off (as you point out). If he moved the hall sensor, he really had to move it as on the BME all you do is screw it back on, it's all set up and fits into the engine so as not to move any from the original spot. Me suspects there's more to it than just a moved magnet.

I'm saving your message for future reference, good work, I always thought you needed a degree wheel, but like anything else there's always another way of doing it, thanks!

visioneer_one

My Feedback: (506)

all RIGHT!

I'm glad I checked this thread before I pulled the motor off the plane. I'm going to reset everything using RCIGN's method to-night. With any luck the neighbors will have to complain about me 50cc noisemaker...

rcpilotjae-RCU

My Feedback: (21)

visioneer_one:

Let us know what happens. (and with the neighbors too.....)

visioneer_one

My Feedback: (506)

Will do.

As for the neighbors - the closest ones are actually a tourist attraction, and among other things play "island music" all day long.


"... Mathilda she take me money an run Venezuela"


Sod the neighbors

rcpilotjae-RCU

My Feedback: (21)

visioneer_one:

It's good to have a hobby (other than R/C) :-)

That's funny...Island music (how do you stand it?)

visioneer_one

My Feedback: (506)

Well! I checked the timing last night using RCIGN's instructions. Found that the ignition was set to fire at approx. 30 degrees before TDC. Small wonder that it kicked. Shifted the ring back 0.026166666666666666666667" then tried starting it again - which after much choking it did!

Right now I've a Bambula 22x10 on it. Low idle was right near 2400 - thank God I tied the plane down securely! The throttle linkage isn't quite right yet, as I couldn't get the idle any lower nor could I shut the engine off from the TX using throttle trim. I'm also going to add a choke servo.

I've no idea what the top end is, nor what to expect. Transition was OK, although it spluttered a bit on the way up. Rich low end, I guess. I'd have worked on it some more but it was too dark to see the needles!

BTW - apart from a few short bursts I kept it at idle. No complaints from the neighbors.