B&S Ignition

Discussion in 'Small Engines' started by billr, Apr 3, 2016.

  1. nickb2

    nickb2 Wrench. I help when I can

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    Bill, I just had a funny idea. While I was typing here, I got a phone call. It was a old buddy looking for some lumber.

    He has two pretty big scary dogs. I said why don't we call them "no spark" and "no carb":D He doesn't speak english, so I had to say to him that a california friend is having troubles with the lawn mowers again. His newest acquisition is an old sears snow blower. The shaft is shard off. He got it for dirt cheap and we will have fun welding something up to get it throwing snow for next winter.

    One sleeps all day, he would be no carb.

    This is where he laughed hard into the phone, the other dog is kind of OCD. It will chew anything to oblivion. He just inherited his new nickname. "no spark"

    Up one minute, down the next. I think that dog maybe have even cracked a tooth chewing on my work boots. The chew marks ended at the front toe of that nice pair of boots.

    I was pissed off cuz I liked those boots. But we figured out why, my current GF works in a meat factory and when she works the marinating sauce fly's everywhere. The dog probably thought it was a steak.

    The plant she works at is "viandes Lacroix" http://lacroixmeats.com/

    I like it when she brings home some souvlaki or even better when she brings home some badly cut tenderloin. I make good ragout from those cuts.

    Another of my friend works for a new shop. Apparently they use a new procedure, "viande sous vide"

    http://naturelxtd.ca/

    He took me to see the process, quite interesting and unique to our region.
     
  2. billr

    billr wrench Staff Member

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    She ran it for another hour this morning, it's back in the garage to get the kill wire back in.
     
  3. billr

    billr wrench Staff Member

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    Well, she and my son have put many happy hours on it now, she is out there knocking down weeds as I type this. The sad thing is that there was never much wrong with it in the first place, just my quest for more JackC-type "experience"! Let me explain...

    Originally I checked for spark and found none, hence the "no spark" moniker for this one. I opened up the covers and immediately disconnected the kill switch, to eliminate that wiring as a problem; still no spark. However, the flywheel cover, including pull-start, had to come off to get in to check the coil air-gap, magnets, and disconnect the kill switch. So, to check for spark, I turned the crank with a socket and speed-handle on the flywheel nut. With the plug out I can turn it pretty fast so expected a good system to spark. Maybe I wasn't turning it as fast as I thought, or maybe the old spark plug was iffy, or maybe I was simply missing the spark because I was doing this out in fairly bright daylight. I think I said, way back, that my method of checking for spark may not have been adequate.

    At any rate, after I installed a new coil, then a new spark plug, and it was still intermittent, I went down the "rabbit hole" of removing the flywheel and setting it up in a lathe to spin it to my heart's content trying to find out why the spark was flaky. The trouble is, I think, that when I made the bracket to hold the coil on the lathe, I tapped a 14mm thread in the bracket to nicely hold the plug. However, the bracket is 5/8" thick and the plug threads are only 3/8" long, so the spark-gap was kind of "down in a well". I was now indoors, of course, so light was dimmer (real dim if I turned out the nearby light) and I felt the spark should be quite visible, even though I couldn't see the gap directly. Well, maybe not. Just to be sure, after walking away from it for a few days I added a hole in the bracket through the side of the plug threads, so that I could see the gap directly, and the spark seemed fine (see reply #40).

    Okay, so as I had it opened up again to re-install the kill switch/wire, I noticed that the kill switch (a very crude design) was only marginally opening up in the "run" position. This was because the switch is operated by lever that applies a brake pad to the flywheel to quickly stop the blade, and that brake lever had a very fierce spring to move that lever and apply the brake. Because of this spring, the small cable that operates the brake/kill is highly loaded, and appears to have stretched just enough so that the operation of everything there was marginal. My perception is that the cable, and lever that operates it up at the handle, are too light-weight for operating that brake spring, perhaps they even pre-date that addition of the safety-at-any-cost blade brake. I think just normal wear on the cable and the various lever pivot-points pushed this one over the edge. So, I put a lighter spring in there, so that everything could move, instead of flexing in various places and the kill switch at the end of this chain opened a reasonable amount. After that, no more problem!

    I am concluding that the problem was the kill switch all along, and that I wasn't testing for spark adequately when I had the switch disconnected, so wrongly concluded that it wasn't the problem.

    By the way, "no carb" may also be healing. I found some small O-rings to use as a new float-needle seat. They didn't fit tightly enough in the carb housing, at first, but had swelled enough after a few days exposure to gasoline that needle seepage is minimal; I think less than engine running-consumption. So, even if it continues to seep, just turning off the fuel valve from the tank when not in use may do the trick.
     

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