Mine is really old, I got that engine used and it has the old style cyclone cleaner and it seeps a little bit of fuel but not much. You may have just got a bad seal in yours.
Well I still need a 1 inch shaft engine for my 4gpm pressure washer build. I'm thinking get a predator 459cc engine put it on the stump grinder since I don't think I need a 670cc engine. The gx390 is supposed to be like 13hp and the pred 459cc is supposed to be about 16hp. I think the 459cc has a 1 inch shafts. But on the stump grinder I don't have to use a 1 inch shaft as I can change the pulley to what ever I need. The 4gpm pressure washer pump I bought at firesale prices during the peak of the plandemic is 1 inch.
Harbor freight has the 459cc engine on sale for 10% off, about $450. So I got one. The air cleaner is shit for my application, it's a warm air intake and does not have dust separation would be fine for something like a pressure washer or generator not ideal for dusty applications like a dune buggy, concrete mixer, mower, wood chipper, stump grinder but I want the intake relocated to fresh air up by the handle bars any ways.
Unlimited power. Well about 3 more horsepower. I have a gokart straight pipe ordered. I just don't have any 1.25 inch pipe with elbows to make it from. It has a 90 day warranty so I figured I better get on it.
The 13 inch stump grinder running 66% under drive powered by the 459cc is nearly unstoppable. It does not lack power. I'm thinking that Honda gx390 was running too rich and may be been losing power due to running so rich. The new predator engine came with 2 other carburetor jets so I put a slightly smaller one in the gx390, I'll see how that does. It's next life is going to be a pressure washer. The 459cc powered stump grinder got its maiden voyage and it's first paid job.
The predator 459cc is a bad ass engine. Hemi head Pretty tough looking rocker setup Cast valve cover Bad ass light weight race piston Pressurized and splash oil system Big 1.25 inch exhaust port Electric start, because you ain't pull starting it Big gas tank Very simple wiring
I got the new straight pipe made. 1.25 inch made from a go-kart pipe kit since I didn't have a source for 1.25 inch pipe or pipe bends. I lucked out at the scrap yard and found 1.25 inch stainless pipe Friday. So that worked out. It's about 4 feet long, a little more than 2x the cylinder volume. Almost enough to start negative super charging, that's where the exhaust cycle evacuates so well there's a slight vacuum in the cylinder and if there's valve overlap then the cylinder prefills with air and fuel.
I was watching tractor pto stump grinder videos. Yeah they are slow. I guess if you have a big enough stump grinder and like a 100hp at the PTO and you can end 2 foot stumps in like 2 passes yeah they are faster. But my stump grinder appears to be faster than 30 and 40hp PTO grinders that have 2x and 3x more power.
This is one of my concerns with burning them. "A fire was covered with dirt and reignited 6 days later by high winds". Sounds a lot like someone was burning a stump. Science wrong? Investigation reveals Marshall Fire was not caused by climate change | Colorado Peak Politics
The predator 459cc engine bad: "The piston is 80 thousands down in the hole" Welp I'll be on the lookout for someone come out with a +2mm stroker crank that's cross drilled. That'll put the piston about where it's supposed to be. "Doesn't have roller bearings and the crank isn't cross drilled". The only logical reason to not use roller bearings is to use replaceable half bearings and cross drill the crank so the rod sees oil pressure, instead of bing splash oiled.
I generally use them as they were intended. But I do minor tuning and mods such as the 4 to 6 foot long straight pipes on the wood chipper and stump grinder, playing with carburetor jets, timing advance, some tuning to get the most power, best fuel economy and longest engine life out now the engine. Most people just buy'em and run'em. Fresh out the box they run rich and are a bit lazy. Running too rich wastes fuel, washes down the cylinder bore causing additional unnecessary wear, dilutes the oil causing the oil to need to be changed more often and/or additional wear on everything else possibly sludge, corrosion, bad. I mod them specific to my application. The stump grinder uses the 4 foot exhaust pipe helps blow the wood chips and dust away from me while I'm using it. The 75 inch straight pipe on the wood chipper sends the exhaust up and away from people. Probably would have to be a custom speed shop who can make custom pistons out of blanks. I really don't need it that bad, I'll see what the mass production options look like when some after market company picks it up. It will either be a taller piston or a cross drilled stroker crank. My price range would be a taller piston. A cross drilled stroker crank would be at least $200. I don't need 12cc and a higher compression that badly.
I'm going to add an oil filter to the stump grinder. Since I'm buying a filter head I'm going to get a 3/4-16 thread head. That way I can put on a 5 micron hydraulic filter with pressure differential indicator gauge.
I can't find that 5 micron 3/4-16 hydraulic filter so I got a no bypass 10 micron one, since it's a non bypass if I lose 20psi across the filter, no problem. A typical cheaper high flow hydraulic filter catchs about 99% of 25 to 40 micron particles. A typical good motor oil filter catches like 99% of 20 microns and a standard cheap one does like 96% of 30 micron.
I pulled a oil sample from the predator 459cc on the stump grinder is and was kind of metallic. Sent a sample off and now time to put a hydraulic filter on.
Isn't it more practical to just use copper sulphate and drill some holes and let the poison do the job?
It takes some stumps 10 years to rot and that's assuming the tree was big and starting to rot a little while it was still alive. Cedar rots very slowly. And there is some other kind of tree, dark red wood smells very nice, wood is very hard they almost don't rot at all.
