I just got a MTD garden tractor/mower. It hasn't been used for several
years, so it needed a new gas line, and some tires replaced. But the
12.5 HP Briggs engine fired right up.
This engine is missing a muffler. It just has a piece of pipe sticking
out about 4". Although the engine runs well, there are blue flames
coming out of that pipe, which shoot out as far almost a foot. I'd guess
that explains why the muffler is gone.
But what puzzles me, is that several times per minute it sounds like a
gun is fired, (explosive sound) and an extra big yellowish flame shoots
out. This does not affect the engine speed, and it keeps running well.
But it is unusual. What could cause this?
It almost seems like a valve is leaking, but I'd think that would also
cause the engine to run poorly.
One thing I have noted is that after I have run this mower for about an
hour, these explosions have become much few per minute, but they still