I would expect a leaky exhaust valve.
My gx390 pressure washer running a 6 or 8 degree timing advance, 4,000rpm, runs wide open throttle, 4gpm pump at 3,600rpm, go-kart intake, runs well tuned wants to die when I start it and needs some choke to stay running until a bit warm. Mobil1 v-twin 20w-50 weight in the engine and mobil1 75w-90 gear oil in the pump.
Timing advance via offset flywheel key?
Just a timing key.
Tow behind 48'' mower deck doing work. MTD 547cc running 4,100rpms.
It burned a quart of gas in a half mile of mowing. Most of it wasn't even that tall.
It didn't even think about slowing down.
It burned a quart of gas in a half mile of mowing. Most of it wasn't even that tall.
It didn't even think about slowing down.
Wow. Don't park it over tall dry grass
Yeah it's already caught on fire once when a spindle locked up.
Glowing exhaust is really common on hard working generators. A 5000W generator running a 4500W water heater is a perfect way to demonstrate a red hot muffler. Thousands of hours on my genset, no failures yet.
My thought on the op's pictures is, that looks like a homemade exhaust pipe extension and mounting bracket. Being that isn't a high performance engine, and given the rise of the pipe, the exhaust gases are taking longer to exit the pipe. Therefore the heat from the gases are lingering in the pipe heating it up. If it were mine, I would reroute the exhaust pipe by first shortening the pipe, upsize the pipe, and pointing it downward. If it was too loud for your liking, add a muffler.,,
The rising mower is a straight pipe that's about 42 inches long. It doesn't get any more free flowing than that.
I made the pipe long enough to promote scavenging.
When you think about performance whether it's for a boat, truck, race car , or motorcycle. The design of the pipe is more important the the length. The shorter the better. The faster you can get the exhaust gases out of the pipe, the better the scavenging effect. A large diameter, and not having to push it upwards works better. The reason the pipe is glowing is because the gases are restricted, and lingering in the pipe too long. Steel pipe becomes brittle after repeated heating and cooling cycles. That why vehicle mfgrs use cast iron manifolds from the factory. Race cars use steel for weight reduction, but will have welds fail and pipes crack after a while.,,
Shorter promotes scavenging at higher RPM, this is lawn mower engine. Fastest it will ever do is about 4,000rpm, most of the time it will be 3,600 or less.
Larger diameter is fine for bigger cylinders. A 1 inch pipe thats around 40 inches long isn't perfect for my 540cc lawnmower. But the 1 inch diameter 75 inch long straight pipe on my 459cc wood chipper is.
I sized the pipe so that at certain speeds the exhaust gas will have built up enough velocity so once the exhaust valve is open the escaped exhausted gas mass is moving at such great velocity that it will continue to try and pull exhaust out of the cylinder.
Yeah, that exhaust looks like some hillbilly engineering. Surprised there’s paint left on hot as red as it is.
It's not paint.
What is it? Metal
It's EMT conduit. I was out of my stainless steel process pipe. It's working really well. If I have to replace it in 5 years I'll be out like $6.
Oh very cool
