OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Other Walk-Behind Rotary Mowers The Rover Pro-Cut Chronicles

Once I got home, I wasted no time and got stuck into mowing the front nature strip to get a feel for it. I then grabbed the tachometer, the 3030 rpm is the fastest standard Briggs 850 I have come across, most of them sit at 2800 - 2900 rpm from the factory. I then grabbed my excellent Knipex curved pliers to bend the governor spring tab towards the front of the engine, bringing it up to a healthy sounding 3670 rpm. This also speeds up the self-propel to a more efficient walking pace.





I do this to all of my engines, usually after the first oil change. I don't necessarily run an engine at 3600 rpm all the time, but it's nice to have some headroom when the going gets tough. And compared to some contractors I see (and hear) going around, 3600 rpm is tame!

The seller mentioned it had synthetic oil in the engine, and it still looked golden, if a little over-full. After tuning the governor, the oil was up to temp, so I decided to change it out for peace of mind. Oil of choice being my usual preference, Penrite 10W-30 semi-synthetic.





While the oil was draining, I took the chance to inspect the blades, which are the OEM style with the three holes. The belt also looks in great condition.





The drive system is a little clunky and needed investigation, which the seller mentioned so it wasn't a surprise to feel this. I did pop off the hub caps and inspection plug to look at the cogs, which looked fine. So, I lubed the cogs with graphite to see how it went, and if needed, I had a replacement set of cogs and pawls. I then removed the gearbox/clutch cover, blew out a small amount of debris and lubed the drive chain.



Next, I decided to pull the plug, which was ok but well worth replacement. The 850-Series uses a Champion RC12YC or NGK BCPR5ES, of which I keep the Champions in stock. You will need a 16mm deep socket for this. I use these plugs across 3 Briggs 850's and one 750iS.









Annoyingly, I didn't have a brand-new air filter in stock. These earlier 850 engines used a longer rectangular filter instead of the triangular version on the newer engines. A clean used filter I already had will have to do for now, which was better than what came off the machine.



To be continued................................