I bought this Yardmax chipper a few years ago as it was all I could afford at the time. I knew that 6HP was certainly inadequate for chipping 3 inch branches as advertised, but I like the hopper, so many affordable chipper/shredders have a tiny hole for chipping which looks like a real pain for feeding in bent, gnarly branches.

With 6HP you can really only chip 1 inch branches, and even then you have to be careful or it will stall out.

So this year I was looking at replacements and to get anything with even 13HP looks to cost around $2600, which seems a bit ridiculous. So Ive been looking into engine upgrades and settled on a Harbour Freight Predator with 15.8HP!

I searched the internet for precedent so as not to be reinventing the wheel, but when my search turned up a blank, I realized I would need to publish my results if successful...

Supplies

I had to buy a new double pulley for the power take off of the new larger motor shaft, new belts, and some sundry pieces of metal scraps and bolts and nuts.

Step 1: Fitting the Motor

The new larger engine wouldn't fit on the mounting plate, so I extended it by bolting on a piece of 3/16" 2 inch angle to the front. It appears to be a sturdy platform.

Step 2: Mounting the Pulley

The Predator has a 1 inch Shaft, v's the B&S's 3/4 inch, so I ordered a new 2 inch double pulley for the one inch shaft with a 1/4 inch keyway. I had to cut about an inch off the shaft as it was that much longer than the old one.

As the new engine is and inch and a half taller to the drive shaft than previous, I bought 24inch long V-belts to replace the ~18inch originals. With the belts stretched tight I bolted drilled holes and bolted the motor in its new position to the mounting plate.

Step 3: Other Upgrades

While I was here I thought I might as well make some other improvements. First off the discharge shoot is too low to get the chips into the trailer I pull around with me garden tractor, so I bolted on a shoot I constructed out of a piece of 1/6th inch steel and the old shoot flap with a door hinge. This hinge allows the shoot to flip out of the way to open the top and clear stuck material and for tight transport areas. I'm super happy with it so far.

Next, I made a tow bar as this bad boy now weighs too much to be moving around by hand, in fact it needed one from the start for moving any great distance. So I cut a hole in a piece of 2 1/2 inch wide steel for a 7/8 inch ball, then bolted on some inch angle for rigidity. It is attached with wing nuts for tool free assembly.

The original wheel base is too narrow and the wheels to small for towing, so I bought a 3 foot axel from Tractor Supply and 16 inch wheels with 3/4 inch axel holes and used electric fence wire to strap it to the frame. Now it sits up a couple inches higher than previously so I added a 2x4 under the front of the frame and 1x1's and a 1x4 on top to hold it together and now it sits level.

Step 4: Putting It Through Its Paces

So, obviously it works, or I wouldn't be wasting my time writing this up..

It is a beast now with 2 and a half times the power it had previously. The chipper originally cost ~$700, the new motor cost me ~$400, the pulley $40, the belts $35, the wheels and axel $60, and the metal whatever and bolts.

Total cost $1264, not bad for a ~16HP chipper.

It mows through material now, but the weak point is the double pulley. Ideally for something of this power a triple pulley would be preferable, however there is not room to install another pulley, so all that can be done is to tighten the pulley adjustment for more friction. If the chipper disk jams though, you have to release the tension ASAP as the belts start smoking almost immediately due to the incredible power from the engine on full throttle.

So due to this weak point I generally don't chip branches larger than 2 inches, and those with the pulse method. Although the deliverable power thorough the belts is not 2 and a half times what it previously was, maybe just 1 and a half times, the greater engine power allows the chipper disk to power up in a fraction of the time it previously took, allowing me to fill the trailer up in under an hour which was taking 3-4 hours with the wimpy 6HP motor.

I also added a ten dollar engine hour counter for accurate maintenance.

All in all, it is a totally worthwhile upgrade, I was going to rent a 30 HP chipper weighing 1700lb to do the bulk of my chipping each year, but the size and weight was going to be troublesome. There is no need for that now, I can do all of my chipping with these 16 horses, I can access anywhere on my property the yard tractor can go, also 3 feet wide, and I can even move it by hand when necessary, though a biaaatch.

I have been clearing hundreds of trees from a few acres to make silvan-pasture for goats and there is A LOT of brush constantly accumulating. I could burn it but this chipper is so much quicker and the chips are so useful around here especially in mud season! I am trying to enrich the soil here and burning would send most of the carbon back into the atmosphere, where it is not exactly needed instead of into the soil where it is.

Score!

Step 5: Quick Chipper Blade Sharpen Hack

I should really make a video of this, and I hope to soon but until that time I need to get this into the world of chipper uses to make everyones life a little easier.

I was taking the blades off to sharpen them each time, it was not fun and quite difficult. I broke an Allan bolt removing it and it took an hour each time making me less likely to keep them really sharp.

The I took the Dremel to it once and never looked back. With this chipper it is possible to sharpen the blades using a sanding wheel on the Dremel while they are still on the chipper disk. It only takes a few minutes, mostly time removing the hopper. Eventually I plan on taking the blades off to put the primary bevel back on, but I might just wait until I want to flip them around, or to replace them. To put the primary bevel back on I have used and recommend an orbital sander for speed and less heat build up, as apposed to a grinder or hand stone.

Good luck you chippers of the world!