Professional Series™ 850

8.50 Gross Torque

Mowing your lawn has never been this easy or enjoyable. The Professional Series™ 850 push mower engine combine professional-grade power and performance with homeowner-friendly convenience and ease of use. Strong, quiet and durable, these lawn mower engines come standard with the ReadyStart® starting system: No priming. No choking. Just pull and go.

  • Starting Promise. 2 attempts or we fix it free!

    Starts in 2 attempts – or we'll fix it for free.*

  • Briggs & Stratton OHV Engine Design
    Overhead Valve (OHV) Engine Design

    OHV engines run cooler and cleaner for better fuel economy and longer engine life.

  • Super Lo-Tone™ Engine Muffler

    A quieter lawn mowing experience.

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*All power levels are stated gross horsepower at 3600 rpm per SAE J1940 as rated by Briggs & Stratton.

*All power levels are stated gross torque at 2600 rpm per SAE J1940 as rated by Briggs & Stratton.

Professional Series™ 850 is rated 4.5556 out of 5 by 9.
Rated 5 out of 5 by from Top notch engine with brilliant berformance. Hi all, I used a Mountfield m4 Major 18'' push mower, which rear discharges and collects with its 5mm thick deck.For approximatley 33 years #from 1977 it had the standard 3.5 hp Briggs and stratton Model 92908 side valve engine, which ran sweet as a nut for all those years and even with that engine the mower coped exellently with long grass. now though the points are pitted so it does not run but that's an easy fix for a good engine.I then decided to go for a 850 I/C series 12Q902 model engine, which I bought for £200 approx from a reputable authorized engine dealer.This is how I rate the engine as a professional user.FeaturesprosCast iron bore will definatley provide a long engine life. high mount oil fill and dual element air cleaner for dusty conditions. super low tone muffler for quieter operation ready start for 1 to 2 pull starts even in winter resin blower housing for no dents.consNo full pressure lube so can't be used on same gradients as 2 stroke engines, if you could design a simple, efective and reliable solution for this problem then then this would be great.No heavy duty bearings as standard as previous reviewer pointed outThis feature is optional and only comes with heavy fly-wheel to the best or my knowlege.Performance.This thing keeps turning near full revs even if the deck clogs with grass because of the torque of the engine. so safe to say that i could even cut down grass that's knee height with virtually no bogging down.I have never had it cut out exept from from tank being empty.The only downer is that there's no full pressure lube available only pressurised oil filter is available not the whole engine so you can't use it on slopes. but otherwise amazing performance for that perfect cut even in damp climates or conditions.economyFull tank will easilly last an hour so it's really good on fuelreliability.starts first time every timewhen engine get's warm it sometimes takes a few pulls to get the engine starteddoes'nt quit or bog gown so better thn the honda gxv160 which boggs down quite often which I have experienced on one mower.I havent had any issues exept fuel jet in carb is minute for emission compliance reasons so it can clogs even if fuel has been filtered with fine mesh funnel but that can be fixed very cheaply for under £10.00 at local Briggs and stratton dealer who will rectify the problem with the correct procedure.durabilityEngine has resin blower housing like Vanguard engines so is resistant to impacts and easy to clean.Dual element air filter with seals for stopping debris entering engine,cast iron sleeve to resist wear and allow a full days operation for a whole week.The only bad point is that it does'nt come with the Heavy duty bearings like the honda gxv160 although in virtually every other way this is the ultimate mower engine even better than kawasaki fj 180v KAI which has less torque and is less reliable because of hunting issues has a shaft which is prone to bending and does'nt have heavy duty bearings but only has plain bearings.SummaryA great engine that's much better priced than its competitors and is more powerful, durable and is generally more reliable than it rivals. A vanguard version would be an exellent addition to the product line with all the features of your big block engines such as a grass cutting screen in the blower housing to stop build up of grass in that area and enhance durability and reliability it could also have a central oil pump with oil cooling heat sink which would alow the operator to safely use mower on any slop they can walk on without damaging the engine.I would highly recomend the 850 I/C engine to any commercial user or home owner with a large amount of lawn to care for.This is the finest engine available for walk behind mowers available today and is hard to beat with bags of power, durability, ergonomics and performance to match.
Date published: 2012-05-19
Rated 5 out of 5 by from A Real Bang for the Buck The 850 (5 hp) B&S is a smoking hot engine that gets the job done!When cutting grass, is seems like an easy task and not a chore when the 850 is running. It helps me with my walking exercise when I want to go at a faster pace while still getting the grass cut in a nice uniform manner. Everyone should try the 850 before buying another manufacturer's product.
Date published: 2012-08-09
Rated 5 out of 5 by from Great Powerplant I purchased this engine to refurbish a John Deere JS63 walk behind I found through an on-line search. It starts first pull everytime and cuts through thick grass easily. I like the Easy Start feature eliminating the need for a primer bulb and the fact that my wife can easily pull the starter cord without feeling intimidated.
Date published: 2012-04-27
Rated 1 out of 5 by from No durability I bought this engine from an authorized Briggs dealer in 2010. First engine came with a cracked block and I had to fight tooth and nail to get it replaced. After two months of battle I finally got a replacement, more due to the excellent folks where I bought it and not on Briggs end. For two years this "Pro" grade engine worked great, started on first pull, plenty of guts and fairly quiet. One month after the warranty ended it's all done. It just stopped running while I was mowing. It did not seize, had plenty of gas, oil was clean and a good filter. Brought it to my repair shop and they said the cam came off the shaft and sheared the oil pump off inside the engine. Briggs response, "Warranty is over". My repair guy plead the case that the rest of the engine was spotless inside and he could not find a reason for the issue, especially not on my end. Briggs response, "Calendar date" meaning once again that I was out of warranty and they would offer no help. So now after 25 years I am no longer a Briggs customer, I will be looking to Honda which is a shame because I believe in buying Amercian Made, but not Briggs....P.S. This was used once a week as a homeowner.
Date published: 2012-09-16
Rated 5 out of 5 by from Best Engine you can put on a push mower and here is why. I don't own this engine but I have a family member who does and I have got to use it a few times.I'm going to compare this engine with a Honda GXV160 and tell you why I would pick this engine if I were to buy another commercial push mower.Alright in terms of power, the GXV160, I'd say that is the single most thing I dislike about it, it doesn't have enough. This engine does have the power and I fear it may have too much in the situation where you hit a big root or something. But still the I give the Power point to the Briggs.Terms of reliability, ok lets see here. In terms of starting, both this engine and the honda are an exceeds...I prefer the one or two pulls on the briggs though, to the manual choking on the Honda. But I'd still say its a draw.Now for the big one, Reliability. Both these engines seem to be reliable, both have something I say could be improved. The Briggs starts easy and runs great, so does the Honda. What could be improved on the Briggs, well a stronger crank, maybe a double ball bearing setup like the honda, because it is more powerful so therefore it would be more likely to break if you hit sidewalk or a root. Easy solution, don't use fancy mowers by sidewalks or rooty trees, I still wouldn't do it with a Honda GXV, just use a cheap mower or a weed eater. Ok now what can the "Legendary" honda improve on? Well, the choke system I mentioned earlier. If you get a branch from a small bush or something in the choke system and it bends, then you are going to have fun fixing it or paying 50 bucks an hour to get it fixed. Honda's GXV engine is no good if you can't set it on the right rpm or choke it, and its sad it relies on a small piece of metal attached to a spring that has a guard that doesn't completely cover the mechanism. Sounds like an achilles heal to me. This actually happened to me lol, my "bullet proof" honda commercial mower. In terms of reliability, I will have to give it too the honda, even though it was close...I'd rather fix a bent piece of metal than a bent crank or worse.Performance, well lets see. Briggs, doesn't bog down even in thick wet grass while mulching. Honda, bogs down in wet grass if you haven't mowed for 10 days. Now in reverse, Honda uses less fuel...and is quieter than the briggs which is still a pretty quiet sounding engine.Verdict- I give it to briggs, I'd rather burn a little more gas and not be restarting my mower every 2 minutes when it bogs.Value- the briggs 850 you can get a new engine for under 850 on amazon, the honda is around 400. Terms of whats more for the buck, I say the briggs only because it is cheaper. But too be fair, if you want a fuel efficient very nice sounding engine, the honda is for you. If you want an engine thats gonna get it done in faster in bad conditions you want the briggs 850.Now in conclusion briggs has more points than the honda on my scale. I think it is more of an ideal choice for most conditions. Easier to get parts for, easier to work on than the honda. But by no way am I saying honda is junk it definitely isn't. But if Honda made a 190 gxv it would be a more fair comparison.
Date published: 2012-05-18
Rated 5 out of 5 by from No Durability To the guy that Briggs wouldn't warranty his engine because the warranty expired.I work for a Power Equipment manufacture. Not Briggs And Stratton. I understand your disappointment at not being offered Good Will assistance but Briggs fulfilled their obligation to the full term of the warranty. Manufactures cannot help with warranty on every request on units beyond the warranty period. It's not like there's huge margins on equipment and a company can give away a replacement for each unit sold. Each situation is different and needs to be judged independently. There obviously was no compelling reason in your particular case.By the way I have this engine and it's awesome.
Date published: 2015-05-23
Rated 5 out of 5 by from Everything was so Excellent. When I fixed this at work, I am totally loving this engine so much. It is so easy to start and very powerful too.
Date published: 2012-08-09
Rated 5 out of 5 by from easy start like this engine. time of ownership will tell on value. The oil pressure on a grade not a standard option will not effect me .
Date published: 2012-08-09
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