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

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.

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.

Replaced a motor on my John Deere Z225 zero-turn lawn tractor. Motor showed up with a broken fuel pump but customer service sent me a new part.Old motor had wiring harness with a red, orange, black, and gray wires (see picture). This engine came with 1 red wire and a 2 wire connector with a gray and black wire. I linked red, black, and gray manually and capped off the old orange wire. This worked.Original motor was rated at 18HP and this one is rated at 17.5HP, but I have not noticed any difference in performance over the first year of use.One other note: the holes used to bolt the engine to the frame were not threaded. Some reviews said that you had to tap/thread the holes. Turns out that all you have to do put the old bolts back in because they automatically thread the softer aluminum.

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.

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've worked on Lawn tractors for many years. I'm 77. I like this engine. It repalced an old 19.5 with a bad cam which I will repair later. IF you use the right mounting bolts they make their OWN threads. Start them half way before putting the engine on the machine then when you tighten them the engine will be very secure. IF you cut threads in this soft metal your engine might get loose. IF this engine had the same old 6 pin wiring harness like the older ones had, I would have been running this today. There is NO wiring diagram in the manuel either.. IF they had included an updated wiring harnass that would be great. Break it in. Change oil the first time after about 10 hours. This engine came with fuel pump and gas lines. All I had did was hook my gas line to their Filter. Everything cost's a tad too much right now, I've paid less in the past for engines but I feel good about this purchase. The last Intec decompresson on cam lasted about two years before the starter would not crank the engine. I hope this cam decompression has no plastic parts.. I have small engines stacking up needing new cams. I'm hoping the decompression on this cam will last a long time like the old ones did. I loved the old briggs engines and I hope to fall in love with this one. I love the 1 cyclinger Briggs engines. They are so easy to work on.