Briggs and Stratton Vertical 17.5 HP 500cc INTEK Engine 9amp 1" x 3-5/32" #31R977-0054

After 22 years the original 18hp B&S engine on my old Troy-bill lawn tractor seized up when the throttle came apart and the screws got sucked into the cylinder. The mower has been serviced and garage kept over the years and is in good shape otherwise, so I didn’t want to scrap it and buy a new mower. I decided to replace the engine with this one after reading the overly positive reviews and received shipment in two days. Even though most say you can get the mounting bolts to work without cutting threads in the mounting holes on the aluminum block, I tapped mine anyway. This engine fit perfectly with the only issue being the vacuum line behind the engine going to the fuel pump is wedged against the fuel tank, but works just fine. There is an extra wire (orange) from the original engine coming from the alternator that is not used in this new engine, otherwise all of the wires are the same color and function. I hooked them up to the old engine side wiring harness connector leaving the orange harness wire cut and capped off. Added oil to the engine, hooked up the gas line and it cranked right up. I’ve mowed twice with it so far and it is every bit as powerful as the original 18 hp engine was and runs smooth. I have a yard with some steep slopes and this engine does not even slow down going up steep grades. As I discovered later, the orange alternator wire on the old engine powered the mower headlights. But I pulled power from the single alternator wire to the light circuit at the ignition switch and the headlights are working again. Time will tell if this engine will be as good as the old one, but for now I feel good about this purchase.

I needed to replace the 16.5 HP B&S motor on my DR ProXL30 brush mower, because the decompression mechanism no long worked and the starter could not overcome the compression. This 17.5 HP B&S motor is a perfect replacement. It comes with starter, electric fuel solenoid, alternator, and magneto, but it does not come with a muffler. Before disposing of the old motor, be sure to save the 3 self-tapping mounting bolts, the connectors from the old motor and the muffler parts. The motor comes with no instructions on mounting or wiring, but it is pretty straight forward. The 3 mounting bolts are self-tapping in the new aluminum motor frame; you do not need to tap the holes. The pulleys and electric clutch are held in place by a single shaft bolt and Woodruff keys, These are easily removed from old motor and fit perfectly on the shaft of the new motor.The new motor comes with 3 wires to be connected to the existing wire harness on the mower - a red for the alternator, gray for the fuel solenoid and black wire for the magneto - but it requires repurposing 3 old connectors (round single pin, flat 2 pin and square 6 pin connector). Basically you connect the gray to the gray, black to the black and red to red using the old connectors (ignore the orange wire) aided by wire quick-connects or wire nuts.After being fueled, the motor started immediately when ignition key was turned. I couldn't be happier with the new motor, but let us hope these new motors will not have the decompression starting problems that plagued the original motors.

After doing a ton of research I found this engine would fit in the same spot as my old 31r907. This model, the 31r977, featured some desirable upgrades like an oil filter and a fuel pump. It was easy to install in the same spot as my old engine. As others have said, do not despair about there not being threading in the mounting holes, your old bolts will make the threads for you. Just start the bolts and turn slowly with a socket wrench.There was some minor wiring I needed to do between the two. What I ended up doing was comparing the old harness to the new one. I de-pinned some of the connectors on the new harness and used the old harness clip to wire into the rest of the lawnmower. Take your time, make sure the wires from the new harness fit into the same spot the old wires did in the old clip, and it'll work perfectly.Something I didn't realize was the old crank bolt is on TIGHT. Be prepared to fight with a bit both getting it on and getting it off. On my 31r907 the torque spec was about 100ft-lbs.This engine does NOT come with oil, be sure to add engine oil before operation. There is a little bit of oil in the crank case probably just for testing.5 stars, anyone with a bit of mechanical knowledge could swap one of these engines. Very easy as far as motors go.

I ordered this engine for my 2011 model Troy-bilt riding mower and was afraid that it wouldn't fit because the design of the new engine looked different. But everything fell into place and I fired it up. Ran like a champ, drove like a champ and now I might get another 14 years out of my mower.

Engine was in immaculate brand-new condition. Packaging very sturdy & thankfully weather-resistant as it was delivered to the wrong address where it sat outside in the rain for a while. Engine & paperwork inside was nice & dry. No defects or faults noted, easily installed & runs like a champ. Would highly recommend this supplier if you are in need of a new engine to refurbish a 23-year-old riding mower.