WAS: Briggs & Stratton Engine Problem

[Manjo]

The earlier thread WAS getting too long and awkward.

I had a question on the spark arrester: the closest thing I can find is a slotted "cap" on the muffler that can be adjusted to direct exhaust. My muffler is similar to the one on page 19, reference number 300D.

The difference is, after removing the deflector, reference number 676, the cylindrical muffler is one welded/soldered piece. I can easily blow 15-psi air through the muffler so I'm assuming it's not clogged. Is this a safe assumption?

I also soaked the carburetor in Berrymans B-19 carb cleaner solution for about 2 hours with no improvement. The bike still takes several pulls to get it started and it has to run at 1/2 choke until it's warmed up enough to run with no choke at all. The engine still does not run at 100% speed even after it's warmed up.

Just a quick summation for anyone tuning in late: thoroughly cleaned/ blew out carb with compressed air, replaced diaphragm, cleaned pick-up tube. Replaced carb gaskets to engine and to gas tank. Thoroughly cleaned out gas tank. Cleaned and re-installed magneto at proper setting/height from flywheel. Changed the spark plug twice. Oil filled to top of filler hole. Compression is 75 psi. Rough leak down test goes to 100 psi with no audible leaks.

I connected a spark gap tester between the spark plug and the cable. I was able to start the engine and run with the tester in place set at approximately 0.030 inches. I get a bluish-orangey color spark across the gap. As the engine slows down, the spark breaks into two orange lines with a little blue now and then. Since the engine runs at good speed with a more blue than orange in the spark, I'm assuming the orange color is there because the gap tester is taking away some of the current.

Thanks,

Manjo 1998 Briggs and Stratton "L" head engine on a Giant-Vac leaf blower

[ransley]

isnt 75 lb low

[Oren]

The orange weak spark, would make me look at the magneto for replacement. As I recall; a magneto will weaken, so will the spark. This is not a total failure of the magneto, but a slow death.

Check for cracks on any wires, also. Just me :))

I suspect the coil on the magneto has a hairline crack, but they can be difficult to detect.

Older cars with cracked coils would run fine, but the day it rained and the coil was hot the cracks expanded to allow moisture in the coil that killed the engine.

A simple thing is to check the plug terminal. Some firing problems can results from a damaged wire. Simple snip the terminator off and replace it.

Thanks for the update. I would like to hear the end results.

[pheeh.zero]

My thoughts are still with the carb...but I would pull the fly and check the key.

[Manjo]

I'll try that. I think I have a couple of spark plug caps I can use. Thanks, Manjo

[Manjo]

Do you think the key is worn or broken?

Manjo

[Manjo]

I don't think I'm getting full power all the time. 75 psi was with a screw-in compression tester. I connected my compressor to the same line and ran the pressure up to 100 psi with the piston at TDC. Since I couldn't find the compression spec for the engine, I was hesitant to push beyond 100 psi any higher for fear of blowing out the head gasket. I get my leak down tester back in a few days. I'll give the piston, rings, and valves a better test then.

I'm also going to try to slowly move the piston through the compression and firing strokes to see if I get any unusual compression loss due to worn rings and/or worn or scored cylinders walls.

Manjo

[pheeh.zero]

Partially sheared perhaps.

[pheeh.zero]

bump!

[pheeh.zero]

bump up